Urinary Tract Consisting Of Kidneys Biology Essay

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The urinary tract consisting of kidneys, ureter and bladder is prone to many diseases ranging from congenital to neoplastic. The patients may be asymptomatic in which cases it would be an incidental finding or he/she may present with symptoms indicative of urinary tract pathology i.e. flank pain, hematuria, fever, burning micturition or palpable mass lesion.

Commonly employed radiological investigations include X-ray, IVP, ultrasound, CT scan and MRI. Each has its own advantages and limitations.

Evaluating by ultrasonography (USG) has an edge over other conventional modalities as It is economical, easily available, non invasive with no radiation hazards, provide real time imaging and can be repeated as and when required. However the major limiting factor is inadequacy of data obtained in excessively obese patients and those with gaseous prominence in abdomen due to loaded colon.

Using multidetector computed tomography (MDCT) scanner, different protocols for scanning can be applied which can be tailored according to patient's complaints and the suspected pathology and the obtained volumetric data reduces the misregistration artifacts and respiratory artifacts.

It is unsurpassed in evaluating lesions containing fat and calcium.

The commonly used technique consists of - non enhanced or plain phase followed by cortico-medullary, nephrographic and excretory phases.

Among the different post processing technique, Maximum intensity projection (MIP) is particularly useful to display vascular structure; volume rendered images are apt to depict both vessels and soft tissue.

AIM AND OBJECTIVES

This study aims to establish the role of MDCT in evaluation of urinary tract pathologies.

AIMS & OBJECTIVES:

To detect urinary tract pathologies.

To ascertain various radiological features and categorize lesions in congenital, infective, vascular, obstructive or neoplastic conditions.

To evaluate the extent of disease process.

To determine the accuracy of the MDCT in diagnosis of urinary tract pathologies and assess the additional information provided by the modality over other investigations.

MATERIALS AND METHODS

During the period from May 2010 TO October 2012, fifty patients with suspected urinary tract disease were examined using MDCT scan as prime diagnostic modality at our institution.

Each patient was studied in detail with relevance to clinical history, examination and laboratory investigation.

USG was done in majority patients prior to CT scan.

INCLUSION CRITERIA

Patients with age ranging from five to seventy five years were included in the study.

Patients presenting with either of the following complaints: abdominal pain, fever, hematuria, abdominal lump, burning micturition.

Laboratory findings like urine examination indicative of urinary tract pathology.

EXCLUSION CRITERIA

Patients with only urinary tract calculi.

Patients with history of trauma.

SCANNING AND METHODS USED

Scanning was done with 64 SLICE MULTIDETECTOR CT SCAN MACHINE.

Volumetric data from diaphragm to rectum were acquired with pitch kept usually at 1 with contiguous 1 mm slices with axial, coronal and sagittal reconstruction.

Images were acquired after

Oral water soluble contrast or oral water.

Rectal contrast when indicated. (In suspected bladder mass or pelvic pathology).

Intravenous iodinated contrast agent, volume of 80-100ml injected at 2-3 ml/sec and different CT scan phases acquired namely plain (or non- enhanced) followed by cortico-medullary, nephrographic and excretory phases.

REVIEW OF LITERATURE

A) Evaluation of Upper Urinary Tract Tumors with Portal Venous Phase MDCT: A Case-Control Study

Study was performed by Max Kupershmidt, Myles Margolis, Hyun-Jung Jang etal in the Mount Sinai Hospital and Women's College Hospital, Toronto, Canada to assess the detection and negative prediction rate of upper urinary tract tumors on portal venous phase MDCT.

This retrospective case-control study included 20 patients with upper urinary tract tumors and 40 age- and sex-matched control subjects. All studies were assessed independently by two reviewers.

It was found that the detection rate of the proximal two upper urinary tract segments was significantly higher than that for the distal segments (p < 0.001). The sensitivity, specificity, and negative predictive value of portal venous phase MDCT for detecting tumors were 95%, 97%, and 100%, respectively.Top of Form

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B) Role of non- contrast CT in evaluation of flank pain and comparison with IV Urography

In 1995 Smith et al. reported on the use of non-contrast CT for evaluation of acute flank pain and compared it directly with IV Urography in 20 patients.

In that series 12 patients had CT and IVU findings consistent with obstruction while 8 had normal studies. Of the 12 patients with obstruction, 5 have a ureteric stones seen on both studies but 6 had a stone seen only on CT.

This led the authors to conclude that "Non-contrast enhanced CT is more effective than IVU in precisely identifying ureteric stones and is equally effective as IVU in the determination of the presence or absence of ureteric obstruction."

C) Arteriographic correlation in 30 patients with renal vascular disease diagnosed with multislice CT.

This study was performed by AU Echevarría JJ, Miguélez JL, Lopez-Romero et al: Medline. Pubmed 2008; 50(5):393.

30 patients with arterial hypertension and/or kidney failure underwent MSCT to rule out a vascular cause and DSA to confirm a vascular cause suspected at MSCT.

The findings at MSCT and DSA were identical in 56 (78.8%) renal arteries; MSCT overestimated the degree of stenosis in 13 (18.3%) cases.

In the diagnosis of hemodynamically significant stenosis, MSCT had a sensitivity of 96.5%, specificity 78.5%, accuracy 85.9%, positive predictive value 75.6%, and negative predictive value 97%.

MSCT is a good noninvasive imaging technique for the evaluation of renal vessels; it is useful for screening patients with kidney disease to rule out potentially treatable vascular causes.

D) Multislice computed tomography urography in the diagnosis of urinary tract diseases .

Performed by Volumen 68, Broj 5 by- Olivera Nikolić, Clinical Center of Vojvodina, Center of Radiology, Novi Sad, Serbia.

It was observed that compared with IVU, MSCTU is more specific for renal parenchymal abnormalities, tumors of the excretory system, urolithiasis, bladder tumors, fibrosis and extra urinary diseases.

MSCTU is equally sensitive, but more specific for hydronephrosis compared to MSCT. The diagnosis made by the use of MSCTU in patients with macroscopic and microscopic hematuria and with obstruction not caused by stones, perfectly complies with operative findings and histological diagnosis.

The only remaining role for IVU is imaging of the upper urinary tract in patients with hematuria under the age of 40.

E) Role of MDCT in the evaluation of patients with Hematuria -

Study undertaken by Sameh Hanna, S.Abdel Rahman, N.Barsoum, HM.El Gammal; Cairo, EG. EUROPEAN SOCIETY OF URORADIOLOGY.

Fifty nine patients presenting with hematuria were diagnosed using different techniques of MDCT, over a period of 2 years. According to the patient's condition & suspected lesion, the protocol of the study was tailored. The cause of hematuria were divided into renal (n=36), ureteric (n=6), vesical (n=4) and urethral (n=13) pathologies.

It was concluded that contrast-enhanced multiphasic MDCT urography can demonstrate a wide spectrum of disease in hematuria patients. Virtual cystoscopy can be beneficial in cases with bladder pathologies and urethral lesions can be properly assessed by CT urethrography.

F) Congenital renal anomalies detected in adulthood

Performed by - Muttarak M, Sriburi T Department of Radiology, Chiang Mai University, Chiang Mai, Thailand. - Biomedical Imaging and Intervention Journal. December 2011.

Between January 2007 and January 2011, the clinical data and imaging studies of 28 patients older than 18 years diagnosed with renal anomaly were retrospectively reviewed.

Of these 28 patients, 22 underwent imaging studies and their results constituted the material of this study.

Of the 22 patients, 14 had horseshoe kidneys (HSK), four had crossed renal ectopia and four had malrotation.

Abdominal radiograph suggested renal anomalies in nine out of 15 studies. IVP, RP, US and CT suggested anomalies in all patients who had these studies performed.

CT was the best imaging modality to evaluate anatomy, function and complications of patients with renal anomalies.

(G) CT urography: definition, indications and techniques. A guideline for clinical practice

Aart J. Van Der Molen, Nigel C. Cowan , Ullrich G. Mueller-Lisse Claus C. A. Nolte-Ernsting et al ; CT Urography Working Group of the ESUR ; Eur Radiol DOI 10.1007/s00330-007-0792-x

They proposed to define CTU as a "diagnostic examination optimized for imaging the kidneys, ureter and bladder".

The examination involves the use of multidetector CT with thin-slice imaging, intravenous administration of a contrast medium, and imaging in the excretory phase. Imaging in the excretory phase, either early or delayed is thus a mandatory part of any CTU protocol.

The aim was to develop clinical guidelines for CTU by a group of experts from the European Society of Urogenital Radiology (ESUR).Expert guidelines on indications and CTU examination technique was produced.

CTU is justified as a first-line test for patients with macroscopic hematuria, at high-risk for urothelial cancer.

Otherwise, CTU may be used as a problem-solving examination. A differential approach using a one-, two- or three-phase protocol is proposed, whereby the clinical indication and the patient population will determine which CTU protocol is employed.

Lower dose (CTDIvol 5-6 mGy) is used for benign conditions and normal dose (CTDIvol 9-12 mGy) for potential malignant disease A low-dose (CTDIvol 2-3 mGy) unenhanced series can be added on indication.

The expert-based CTU guidelines provide recommendations to optimize techniques and to unify the radiologist's approach to CTU.

RADIOLOGICAL ANATOMY OF KIDNEY, URETER AND BLADDER

KIDNEYS

Gross anatomy

Lie in the superior part of the retroperitoneum on either side of the vertebral column approximately at the level of L1-L4.

Right kidney usually lies slightly lower than the left.

Bipolar length of the kidney is usually approximately 11 cm. Discrepancy between right and left renal length of up to 1.5-2 cm is within normal limits.

Structure

Cortex forms the outer third; medulla forms the inner two thirds of kidney.

Columns of Bertini extend medially into the medulla between the pyramids.

Pyramids are cone-shaped, with the apex (the papilla) pointing into the renal hilum.

Each papilla projects into the cup of a renal calyx, which drains via an infundibulum into the renal pelvis.

Pelvis is a funnel-shaped structure at the upper end of the ureter. It normally divides into two or three major calyces.

Each major calyx then divides into two or three minor calyces, which have a cup-shape, indented by the apex of the accompanying renal pyramid.

The renal hilum contains the renal pelvis, the renal artery, the renal vein and lymphatics, all of which are surrounded by renal sinus fat.

Renal arteries, veins and lymphatic drainage

Arise from the abdominal aorta, at the level of the superior margin of L2, immediately caudal to the origin of the SMA.

It divides at the renal hilum into three branches. Two branches run anteriorly, supplying the anterior upper pole and entire lower pole, and one runs posteriorly supplying the posterior upper pole and mid pole.

The right renal vein has a short course, running directly into the IVC. The left renal vein runs anterior to the abdominal aorta and then drains into the IVC. It receives tributaries from the left inferior phrenic vein, the left gonadal and the left adrenal vein.

Lymphatic drainage follows the renal arteries to nodes situated at the origin of the renal arteries in the para-aortic region.

Nerve supply

The sympathetic nerves supplying the kidney arise in the renal sympathetic plexus and run along the renal vessels.

Afferent fibers travel with the sympathetic fibers through the splanchnic nerves and join the dorsal roots of the 11th and 12th thoracic and the 1st and 2nd lumbar levels.

Fascial spaces around the kidney

The kidney is surrounded by perirenal fat, which is completely encircled by a Gerota's fascia anteriorly and Zuckerkandl's fascia posteriorly which meet on lateral aspect to form the lateral conal fascia.

Relations of the right kidney

Superior: right suprarenal gland, liver.

Anterior: second part of the duodenum, right colic flexure.

Posterior (same on both sides): diaphragm, costodiaphragmatic recess of the pleura, the 12th rib and muscles of the posterior abdominal wall.

Relations of the left kidney

Anterior: left suprarenal gland, spleen, stomach, pancreas, the left colic flexure, and loops of jejunum.

URETERS

Anatomy

It is a fibro muscular tube, lined with transitional mucosa, which is formed as the funnel of the renal pelvis narrows, at the pelviureteric junction (PUJ).

It is 25 cm long and at the pelvic brim, it runs anterior to the bifurcation of the common iliac vessels, in front of the sacro-iliac joint and then down the postero-lateral wall of the pelvis in close relation to the internal iliac vessels.

At the level of the ischial spines, it turns anteromedially to join the trigone of the bladder at the vesico-ureteric junction (VUJ), which lies at the posterolateral angle of the bladder.

There are three normal narrowings of the ureters (where stones most commonly impact):

At the pelvi-ureteric junction

At the ureter crosses the pelvic brim

At the vesico-ureteric junction.

Blood supply and lymphatic drainage

Upper - ureteric branch of the renal artery.

Mid - Branches of the gonadal artery

Lower -Branches of the internal iliac artery

There is accompanying venous drainage.

Lymphatic drainage is into the lateral para-aortic nodes and the internal iliac nodes in the pelvis.

Nerve supply

Sympathetic nerves to the ureter arise from the renal and gonadal plexuses (T12-L2) and, in the pelvis, from the hypogastric plexus. Afferent fibers return along the sympathetic pathways to enter the spinal canal at the L1 and L2 intervertebral foramina.

Relations of the ureters

Anterior(right): duodenum (2nd part), right gonadal, right colic and ileocolic vessels and the root of the small bowel mesentery, the terminal ileum and appendix.

Anterior(left): left gonadal and left colic vessels, loops of small and large bowel and the sigmoid mesocolon.

Posterior(right and left): psoas muscles, and in the pelvis, the bifurcation of the left common iliac vessels.

Male pelvis- ureter passes over the seminal vesicles and then hooks under the vas deferens before entering the bladder.

Female pelvis- ureter runs inferior to the uterine artery in the broad ligament of the uterus, and lies adjacent to the lateral fornix of the vagina prior to entering the bladder.

URINARY BLADDER

Anatomy

Pyramidal in shape, lies entirely within the pelvis.

Apex lies behind the upper border of the symphysis.

The inferior angle or neck gives rise to the urethra, surrounded by the involuntary internal urethral sphincter.

The superior surface of the bladder is completely covered by peritoneum.

In the male, the neck of the bladder rests on the prostate gland, whereas in the female it rests directly on the pelvic fascia above the urogenital diaphragm.

When the bladder fills, it becomes ovoid and the superior surface rises extraperitoneally into the abdomen.

Blood supply

Superior and inferior vesical arteries.

The veins of the vesical plexus drain to the internal iliac veins.

Lymph drainage is to the internal iliac, thence to the paraaortic lymph nodes.

CLASSIFICATION OF URINARY TRACT PATHOLOGY

** KIDNEY**

[I] CONGENITAL

(A) Anomalies of number or development:

-agenesis

-hypo genesis

(B)Anomalies of rotation / Malrotaion:

-non-rotation or incomplete rotation

(C)Anomalies of position:

-ectopic kidney

-crossed fused ectopia

(D)Anomalies of fusion:

-horse-shoe kidney

-duplex kidney

(E)Potter's diseases:

- I Autosomal recessive polycystic kidney disease

-II Multicystic dysplastic kidney

- III Autosomal dominant polycystic kidney disease

[II] INFECTIVE/INFLAMMATORY

-Acute and chronic pyelonephritis

-Emphysematous pyelonephritis

-Xanthogranulomatous pyelonephritis

-Acute focal bacterial nephritis

-Renal abscess

-Papillary necrosis

-Parasitic infection

-Tuberculosis

[III] OBSTRUCTIVE

-Hydronephrosis i.e. mild, moderate, severe

-Pyonephrosis

[IV] NEOPLASTIC

Benign:

Oncocytoma

Angiomyolipoma

Lipoma

Renal cell adenoma

Malignant:

Renal cell carcinoma(Adenocarcinoma)- clear cell, papillary, chromophobe and multicentric

Urothelial carcinoma-transitional cell carcinoma, squamous cell carcinoma

Lymphoma

Wilms tumor

Metastatic tumors

[V] VASCULAR

-Accessory renal arteries

-Hypoplastic renal artery

-Renal artery stenosis (atherosclerosis, fibromuscular dysplasia, takayasu arteritis etc)

-Renal vein thrombosis

-Renal infarct

[VI] MISCELLANEOUS:

Reflux nephropathy

**URETER**

[I]CONGENITAL

-Pelvi-ureteric junction obstruction

-Duplex ureter

-Ureterocoele

-Primary mega ureter

[II]ACQUIRED (mostly leading to obstruction)

(A)Intraluminal causes:

-Calculi

-Blood clots

-Sloughed papilla

-Fungal ball

(B)Intramural causes (majority lead to formation of stricture):

{i}Inflammatory - tuberculosis, schistosomiasis, radiation ureteritis

{ii}Neoplastic - malignant transitional cell carcinoma, benign papilloma and extension from carcinoma of bladder, cervix, prostate

(C)Extraluminal causes

-Retroperitoneal fibrosis

- Retroperitoneal lymphadenopathy

-Large pelvic tumors

**URINARY BLADDER**

[I]CONGENITAL

-Exstrophy

-Urachal anomalies i.e. patent urachus, urachal cyst, urachal sinus, urachal diverticulae

[II]INFECTIVE

-Tuberculous cystitis

-Acute and chronic cystitis

-Emphysematous cystitis

[III]NEOPLASTIC

Benign: Urothelial papilloma

Malignant: transitional cell carcinoma, Squamous cell carcinoma and adenocarcinoma

[IV]MISCELLANEOUS

-Diverticulae

-Cystocoele

-Fistulae i.e. vesico-vaginal, vesico-enteric

MDCT APPEARANCE OF URINARY TRACT PATHOLOGY (COMMON PATHOLOGIES)

KIDNEY

[I] CONGENITAL:

AGENESIS:

Incidence - 1:1000 population.

Complete absence of renal tissue resulting from failure of the ureteric bud to contact the nephrogenic blastema.

Ipsilateral ureter and renal artery absent.

Bilateral agenesis - incompatible with life.

Association with VACTERL, Fanconi syndrome, Kallman syndrome.

CT scan- non visualization of one kidney in renal fossa or any ectopic site and compensatory hypertrophy of contra lateral kidney.

HYPOPLASIA

Also known as dwarf kidney and is slightly smaller in size than normal.

NECT - small sized kidney, CECT - shows uniformly hypoplastic renal artery with compensatory hypertrophy of contralateral kidney.

D/D - chronic pyelonephritis (shows cortical scarring).

ANOMALIES OF ROTATION / MALROTATION:-NON-ROTATION OR INCOMPLETE ROTATION

Normally during ascent from pelvis to its final position during fetal life the kidney rotates by 90* so that the hilum faces medially and slightly forward.

Any anomaly in this process results in malrotation.

On CECT - malrotated kidney with abnormally directed hilum which commonly faces anteriorly.

Excretory phase - outlines the axis of PC system and the ureter.

ECTOPIC KIDNEY

Abnormally positioned kidney on same side as the vesical opening which may be cranial or caudal to the normal site.

Ectopic sites - iliac fossa, pelvis intrathoracic (rare).

NECT scan- localization of ectopic kidney; Arterial phase - helps in mapping of renal vasculature which may have an aberrant origin.

In case of intrathoracic kidney, CECT shows the diaphragmatic defect through which the kidney passes and also its vascular supply from main or accessory renal arteries.

CROSSED FUSED ECTOPIA

Incidence - 1:1,000 births, M > F.

Refers to an anomaly where the kidneys are fused and located on the same side of the midline.

NECT - delineates the location and boundaries of the fused kidneys, arterial phase - helps in demonstrating the vascular supply and the excretory phase - reveals functioning.

HORSE SHOE KIDNEY

Incidence: 1:400

Characterized by the fusion of the lower poles across the midline resulting in an isthmus of tissue (parenchymal or fibrous) between the two which is located anterior to the aorta.

NECT - localization of kidneys and detection of calculi. CECT - demonstrates whether the isthmus is composed of functioning renal parenchyma or the fibrous tissue on the basis of enhancement characteristics and excretion of contrast.

Renal parenchymal changes (scarring, cystic disease) and collecting system abnormalities (duplex system, hydronephrosis) can also be diagnosed.

DUPLEX KIDNEY

Shows two separate pelvicalyceal systems. The two draining ureters may join before emptying into the bladder (partial duplication / bifid ureters) or insert separately into the bladder (complete duplication).

CT Urography - duplex kidney is well seen with double ureters which may be partial or complete.

POTTER'S DISEASES:

{I} AUTOSOMAL RECESSIVE POLYCYSTIC KIDNEY DISEASE

Most common heritable disease manifesting in infancy and childhood.

Kidney and liver commonly involved.

CECT scan kidneys are enlarged with a smooth outline and low attenuation with foci of renal calcifications. Focal liver cysts and findings of portal hypertension may be seen.

{II} MULTICYSTIC DYSPLASTIC KIDNEY

Developmental, non hereditary anomaly with multiple, smooth nonfunctioning, non-communicating cysts.

Typically unilateral, bilateral form usually associated with congenital gastrointestinal and cardiac abnormalities.

On CT scans in type IIA kidney is enlarged due to polymorphic and multilocular cysts while in type IIB kidney is smaller.

{III} AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Hereditary disorder characterized by cysts in kidney, liver, pancreas, and ovary and associated with intracranial aneurysms.

85% cases - abnormal gene on short arm of chromosome 16; 5-10% abnormal gene on long arm of chromosome 4.

CECT scan - evidence of multiple cysts of varying sizes with enlarged kidneys; excretory phase - Normal functioning.

[II] INFECTIVE/INFLAMMATORY

ACUTE PYELONEPHRITIS

Inflammatory process affecting the collecting system and the renal interstitium; the underlying etiology can be bacterial, fungal or rarely viral.

NECT - renal swelling and parenchymal density may be reduced, or increased if there is hemorrhage.

On CECT- enhancement typically patchy, with band and wedge-shaped areas of decreased enhancement extending from the papillae to the renal margin seen best in nephrogram phase.

EMPHYSEMATOUS PYELONEPHRITIS

Severe renal infection with gas forming organisms characterized by presence of gas in the renal parenchyma or collecting system. Commonly seen in diabetics.

Type I - less common, parenchymal destruction and gas within with no evidence of any fluid collection.

Type II -more common, shows intrarenal gas, renal and perirenal collections and gas within the pelvicalyceal system.

NECT and CECT scans ideal to detect presence of air, its site within kidney as well as perirenal and pararenal extensions.

XANTHOGRANULOMATOUS PYELONEPHRITIS

Rare chronic granulomatous inflammation in patients with stones and obstruction.

Characterized by destruction and replacement of renal parenchyma with lipid laden macrophages which are PAS positive.

Stages are: I- only kidney involved, II- extension in Gerota's fascia, III- perinephric extension.

CT scan - calculi, calcifications and non enhancing cystic xanthoma collections with renal vein thrombosis (less common).

ACUTE FOCAL BACTERIAL NEPHRITIS

CECT scan - focal areas of low density with patchy enhancement and lack of well defined wall.

D/D: renal abscess (enhancing well defined wall).

RENAL ABSCESS

CECT scan - sharply marginated area of low attenuation due to necrosis surrounded by a peripheral enhancing rim indicating a mature abscess.

Detects changes in renal contour, parenchymal density, enhancement pattern, thickening of Gerota's fascia, psoas muscle involvement.

PAPILLARY NECROSIS

Etiology - diabetes, analgesic abuse, sickle cell disease, dehydration, hemophilia.

CT scan - acute form consisting of enlarged kidneys with severe papillary sloughing ; chronic form which shows patchy or diffuse involvement but IVP is more specific ( egg in cup sign, lobster claw sign and signet ring sign).

PARASITIC INFECTION

Most common - hydatid cyst formation.

CECT scan - focal cystic masses, usually thick walled and irregular and may show calcification of crushed eggshell pattern.

TUBERCULOSIS

Feature of post primary tuberculosis with reactivation at the cortico medullary junction followed by local infiltration into the parenchyma with papillary necrosis.

Bacilli enter the collecting system resulting in multifocal stricturing and formation of caseous pus and calcification.

CECT - hydro calyces and/or a hydronephrosis, with debris, areas of calcification and parenchymal loss.

CHRONIC PYELONEPHRITIS

Chronic inflammation characterized by cortical scarring overlying the involved calyx leading to small contracted kidney.

D/D: CT scan shows cortical scarring and helps to differentiate it from fetal lobulation (scar in between calyces) and congenital hypoplasia (less than five calyces with smooth uniformly hypoplastic renal artery.)

[III] OBSTRUCTIVE

HYDRONEPHROSIS I.E. MILD, MODERATE, SEVERE

It refers to distension and dilation of the renal pelvis and calyces caused by obstruction of the free flow of urine from the kidney. Untreated, it leads to progressive atrophy of the kidney.

CT scanning should be performed if the ultrasonography results are inadequate or inconclusive.

PYONEPHROSIS

Refers to infection in an obstructed collecting system (due to calculi, stricture or tumor) with suppurative destruction of renal parenchyma

CT scan shows evidence of hydronephrosis which is hyperdense as compared to fluid (urine) density or heterogeneous. CECT shows irregular, thickened and heterogeneously enhancing Urothelial lining.

[IV] NEOPLASTIC

ONCOCYTOMA

Benign renal tumor; asymptomatic or abdominal lump.

CT scan - large well demarcated tumors with perinephric fat-stranding may be present  due to edema

CECT - variable enhancement with central stellate non-enhancing scar (in 1/3rd cases).

ANGIOMYOLIPOMA

Most commonly in Adults (F>M).

Benign mesenchymal neoplasm; composed of variable proportions of blood vessels, smooth muscle, and adipose tissue.

Sporadic or seen in association with phakomatoses, tuberous sclerosis, VHL or NF1. 

CECT scan - demonstrate fat density and an enhancing solid component within the lesion.

RENAL CELL ADENOMA

Found in patients with acquired renal cystic disease and those undergoing long term hemodialysis.

Indistinguishable from renal cell carcinoma on imaging characteristics.

RENAL CELL CARCINOMA (ADENOCARCINOMA)- CLEAR CELL, PAPILLARY, CHROMOPHOBE AND MULTICYSTIC

Most common primary renal malignant neoplasm in adults.

M>F

Complaints: macroscopic hematuria, flank pain, palpable mass.

NECT scans - iso-, hypo- or hyper attenuating; Calcifications usually amorphous.

CECT scan - solid and heterogeneously enhancing. Sometimes RCC is a predominantly cystic mass, with thick septa and wall nodularity.

Accurate identification of involvement of the renal vein and inferior vena cava is very important for correct patient management. The reported accuracy using CT is approximately 96%.

Thrombus is seen as a filling defect within the vein .It is possible to differentiate tumor thrombus from bland thrombus by the enhancement seen in the later.

CT is a sensitive method for the detection of lung metastases.

TRANSITIONAL CELL CARCINOMA, SQUAMOUS CELL CARCINOMA

Rare in the kidneys, located more centrally and towards the hilum.

CT scans - irregular filling defects of the pelvicaliceal system and ureters, which tend to be associated with obstruction and dilatation of the ureter and pelvis proximal to the lesion with associated wall thickening.

LYMPHOMA

Part of multi-systemic lymphoma, rarely as a primary disease.

Flank pain, weight loss, and hematuria, mass or acute renal failure.

Typical patterns - single/multiple masses or diffuses renal infiltration which is almost always bilateral disease with renal enlargement.

Atypical pattern - spontaneous hemorrhage, necrosis, cystic changes and calcification.

WILMS TUMOR

Most common primary malignant renal tumor of childhood.

CECT - large, at least partially intrarenal mass that usually has a central density and presence of pulmonary metastases at the time of diagnosis.

Associations : WAGR , Denys-Drash or Beckwith-Weidmann syndrome

METASTATIC TUMORS

Common primary sites are breast, bronchus, gastrointestinal tract, melanoma and lymphoma.

Can also be due to direct extension of tumor from pancreas, adrenal.

CECT - single/multiple heterogeneously enhancing diffuse lesions easy to diagnose in setting of a known primary.

[V] VASCULAR

ACCESSORY RENAL ARTERIES

Common developmental variant seen in up to 25% of live births.

Failure of involution of one or more of the arteries acquired during ascent of kidney.

Significance - If certain surgical procedures are being considered (partial nephrectomy, renal transplantation) identification very important to prevent complications.

On CT scan in arterial phase, their origin and course is well delineated.

HYPOPLASTIC RENAL ARTERY

D/D: contracted pyelonephritic kidney.

Kidney is smaller with smooth contour, in contrast to the irregular contour of the small kidney in chronic pyelonephritis.

The artery of the hypoplastic kidney is described to be uniformly narrow in its whole length, (pyelonephritis - origin of the artery has as a rule normal width, although the rest of the artery may be narrow).

RENAL ARTERY STENOSIS (ATHEROSCLEROSIS, FIBROMUSCULAR DYSPLASIA, TAKAYASU ARTERITIS)

Potentially reversible cause of hypertension.

Less than 5% of adult patients with hypertension.

MDCT - reliable, noninvasive screening examination for the detection of RAS with nearly 100% specificity in the diagnosis of severe (>50%) stenosis of the renal artery.

Depicts secondary signs of RAS - poststenotic dilatation and renal atrophy and decreased cortical enhancement.

Atherosclerotic disease - most common cause (old age; M>F). Plaque and calcification are located at the proximal renal artery near the orifice.

Fibro muscular dysplasia affects young or middle-aged women and lesions are seen in mid or distal main renal artery.

It is classified as -intimal, medial and adventitial fibroplasias.

Medial fibroplasia - most common type ; multiple ridges, which appear as alternating areas of narrowing and dilatation on CT scan i.e. "string of beads".

RENAL VEIN THROMBOSIS

Causes in children- dehydration and sepsis, in adults -glomerulonephritis, collagen vascular disease, diabetes, Trauma, tumors.

In the acute state -hypo attenuating filling defect within an enlarged renal vein and thrombus can extend into IVC and grow toward the right side of the heart.

The presence of inhomogeneous enhancement in the thrombus is indicative of tumor involvement.

In chronic state - thrombus may contract and extensive collateral vessels may develop.

Enlargement of the ipsilateral kidney, edema in the renal sinus and perinephric space, and the coarse striations of a diminished nephrogram may be present in case of renal vein thrombosis.

RENAL INFARCT

CECT scan showing low-attenuation, often wedge-shaped non enhancing peripheral masses.

[VI] MISCELLANEOUS:

REFLUX NEPHROPATHY

Renal cortical scarring develops in association with dilated calyces due to severe VUR and UTI.

Different grades of VUR are:

I-Reflux into the ureter alone

II-Reflux into the ureter and pelvis

III-Reflux into ureter and pelvis with mild dilatation

IV-Reflux into ureter and pelvis with moderate dilatation and preservation of the papillae

V-Reflux into ureter and pelvis with gross hydronephrosis and obliteration of the papillae

Though the diagnosis of VUR is made on MCU, CT scan can reveal cortical scarring, calyectasis, hydronephrosis and hydroureter.

URETER

[I]CONGENITAL

PELVI-URETERIC JUNCTION OBSTRUCTION

Present at any age. M=F.

Hydronephrosis with a narrowed PUJ, which fails to relax and transmit the peristaltic wave to the ureter.

Possible causes: intrauterine ischemic insult, excess collagen within the wall of the PUJ, presence of aberrant blood vessels.

MDCT - anatomy of PUJ obstruction, revealing an intrinsic or high-insertion PUJ, crossing vessels and their relationship to PUJ which can guide to the most effective treatment modality.

DUPLEX URETER

Common, being found in 10% of the population and are characterized by two ureters and renal pelvis.

Incomplete duplication(the ureters fusing at some point in their course and having a common distal ureter and orifice)- in few cases it may be associated with yo-yo reflux.

Complete duplication (both ureters having separate distal orifices) - The lower renal moiety drains via the ureter with the orthotropic insertion but is often associated with VUR.

The ureter draining the upper moiety is inserted ectopically and its termination is always distal to the lower moiety insertion.

The upper moiety ureter has a strong association with Ureterocoele formation.

CECT scan shows an enlarged kidney with two PC systems and ureters in uncomplicated cases and hydronephrosis, functioning of the moieties, Ureterocoele in the rest.

URETEROCOELE

Cystic dilatation of the distal intravesical segment of the ureter with protrusion into the bladder lumen

On CECT scan, round or oval density of opacified urine (in the dilated distal segment of the ureter) separated from opacified urine in the bladder by a thin (2- to 3-mm) halo representing the wall of the prolapsed ureter and the bladder mucosa (cobra head sign).

PRIMARY MEGA URETER

Due to congenitally abnormal musculature of the distal ureter, leading to focal failure of peristalsis. The ureter above the abnormal segment becomes dilated.

Bilateral in 25% with a male preponderance.

Increased risk of infection and calculi.

[II]ACQUIRED (mostly leading to obstruction)

(A)INTRA-LUMINAL CAUSES:

Calculi, Blood clots, Sloughed papilla, fungal ball- lead to varying degrees of obstruction and proximal dilatation of ureter and PC system.

On NECT scan calculi generally appear as hyperdense whereas the rest can show variable densities.

Excretory phase help to distinguish between partial and complete obstruction.

(B)INTRAMURAL CAUSES (MAJORITY LEAD TO FORMATION OF STRICTURE):

TUBERCULOUS URETERITIS

CECT ureteric dilatation, calcification and calyceal abnormalities. Ureteric changes are those of edema and thickening, progressing to multifocal ureteric strictures.

SCHISTOSOMIASIS

Usually affects the bladder, but reflux can lead to ureteric involvement and the development of ureteritis evolving into a stricture.

MALIGNANT TRANSITIONAL CELL CARCINOMA

On CECT it can present as:

an intraluminal filling defect with surrounding ureteric dilatation;

contiguity of the lesion with the ureteric wall;

a stippled appearance caused by contrast material entering the interstices of the tumor;

Varying degrees of proximal obstruction.

EXTENSION FROM CARCINOMA OF BLADDER, CERVIX, PROSTATE

Most common malignant etiology.

Carcinoma of the ovary, cervix, uterus, colon, bladder and prostate may invade the ureters by direct extension or by spread to periureteric lymph nodes.

CECT - evidence of ureteric obstruction with the identification of main pathology.

(C)EXTRA LUMINAL CAUSES

RETROPERITONEAL FIBROSIS (PERIAORTITIS)

Ureters displaced medially and narrowed at the L4-5 level.

The degree of calyceal dilatation may be mild despite the presence of obstruction.

NECT and CECT - a plaque-like mass surrounding the aorta or iliac arteries. The mass tends not to displace the aorta anteriorly. There may be loss of the fat plane between the mass and the psoas muscle.

URINARY BLADDER

[I]CONGENITAL

EXSTROPHY

M>F, association with epispadias.

Rare, bladder is open anteriorly which varies in severity from a small opening in the anterior abdominal wall to complete absence of the anterior bladder wall.

There is usually separation of the symphysis pubis and there may be associated spinal and anorectal anomalies but with normal upper urinary tracts.

[II]INFECTIVE

ACUTE CYSTITIS

MDCT not necessary for diagnosis; ultrasound and laboratory investigations suffice.

However, for recurrent cystitis or in the presence of antibiotic resistance, the entire urinary tract should undergo imaging to look for any underlying abnormality.

CECT and full bladder images - thickened, irregular, trabeculated bladder wall with signs of underlying etiology if any.

TUBERCULOUS CYSTITIS

Characterized by gradual increase in the thickness of the bladder wall and increasing diminution of the volume.

VUJ orifices are affected by progressive fibrosis, with subsequent hydronephrosis and hydroureter.

NECT - patchy bladder calcification. CECT - small capacity bladder with thickened wall. CT SINOGRAM - Fistulae or sinus tract visualised (rare).

CHRONIC CYSTITIS

It may be characterized by gross wall thickening, reduction in bladder capacity and the development of VUR and/or ureteric dilatation.

Rarely does it lead to the development of squamous metaplasia, which may be associated with white patches (leucoplakia).

Full bladder images - small contracted bladder with diffusely thickened irregular wall.

EMPHYSEMATOUS CYSTITIS

Rare, associated with diabetes mellitus and is usually due to E. coli.

NECT- Mural and luminal gas easily identified (by Hounsfield units).

The gas may ascend into the ureters and pelvicalyceal systems.

SCHISTOSOMIASIS

Usually caused by Schistosoma haematobium.

NECT - characteristic calcification of the bladder wall noted.

CECT - Single or multiple discrete filling defects (may produce a honeycomb appearance).

[III]NEOPLASTIC

BENIGN i.e. PAPILLOMA

Benign, frond like tumor that usually arises on the trigone; considered as a low-grade malignancy.

CECT and full bladder phases - Solitary or multiple polypoid defects with smooth or irregular margins, no evidence of bladder wall invasion.

MALIGNANT i.e. TRANSITIONAL CELL CARCINOMA

Age : >50 years M> F; complaints of hematuria, frequency, and dysuria.

NECT - hypodense polypoidal sessile or pedunculated mass lesion with occasional calcification.

CECT- variable heterogeneous enhancement enlarged pelvic lymph nodes, liver, lung or skeletal metastases if any.

Full bladder - polypoid defects that arise from the bladder wall and are fixed in position.

[IV]MISCELLANEOUS

DIVERTICULAE

Focal herniations of the urothelium and submucosa through weak sites in the bladder wall.

Etiology - due to chronic elevation of the intravesical pressure associated with bladder outflow obstruction or neurogenic bladder, especially in old age.

In the early stages, sacculations and trabeculations are identified. As they enlarge above two centimeters they become defined as diverticulum.

CECT with full bladder images - smooth inner wall of the diverticulum, often associated with a trabeculated bladder.

Prone to calculi, infection and occasionally malignancy.

CYSTOCOELE

Abnormal bladder descent associated with genital organ prolapse.

Stress incontinence, bladder outflow or distal ureteric obstruction.

Full bladder images - Descent of any part of the bladder that reaches the inferior pubic rami or below indicates a cystocele.

ENTEROVESICAL FISTULA

Etiology - diverticulitis, neoplasm, and inflammatory bowel disease, radiation therapy, pelvic surgery.

M>F, but women are at significantly increased risk after hysterectomy.

CECT - should be performed prior to instrumentation of the bladder. It may or may not demonstrate the fistulous tract but other suggestive findings are well depicted like intravesical air, focal bladder wall thickening, and extra luminal masses.

VESICOVAGINAL FISTULAE

Etiology - complication of childbirth, hysterectomy.

Presenting complaint - constant watery leakage per the vagina.

Delayed CECT shows excretion of intravenous contrast material into the vagina was observed in 60% of cases, strongly suggesting the diagnosis.

Air or fluid in the vagina may also be present.

OBSERVATION AND ANALYSIS

NUMBER OF PATIENTS IN EACH AGE GROUP

AGE

FREQUENCY

Percent

>10 - 20

5

10.0%

>20 - 30

5

10.0%

>30 - 40

5

10.0%

>40 - 50

8

16.0%

>50 - 60

12

24.0%

>60 - 70

13

26.0%

>70 - 80

2

4.0%

Total

50

100.0%

Urinary tract pathologies are commonly seen in age groups between 50 to 70 years (almost 50% patients)

SEX DISTRIBUTION OF THE PATIENT POPULATION

SEX

FREQUENCY

F

24

M

26

Total

50

PIE CHART DEMONSTRATING THE SAME

No sex predilection for urinary tract pathologies in general was observed in the present study with almost equal number of males and females.

(C) NUMBER OF PATIENTS WITH SPECIFIC COMPLAINS

COMPLAINS

NO. OF PATIENTS (OUT OF 50)

PAIN

21

FEVER

16

HEMATURIA

10

BURNING MICTURITION

13

PALPABLE MASS

10

Majority of patients have complaint of pain (42%).

(D) SEX DISTRIBUTION OF THE BASIC UNDERLYING PATHOLOGIES

sex

BENIGN NEOPLASM

CONGENITAL

CONGENITAL & OBSTRUCTIVE

INFECTIVE

INFECTIVE & OBSTRUCTIVE

MALIGNANT NEOPLASM

MALIGNANT NEOPLASM & VASCULAR

MISCELLANEOUS

OBSTRUCTIVE

OBSTRUCTIVE AND MISCELLANEOUS

VASCULAR

TOTAL

F

3

5

1

7

0

4

0

1

0

1

2

24

M

1

4

0

8

1

8

1

0

1

0

2

26

No sex predilection was noted in infective pathologies.

More number of females had benign pathologies as compared to males.

However in case of malignancies, the numbers of males were almost double the number of females.

(E) FINDINGS ON URINE EXAMINATION

MICROSCOPY

NO.OF PATIENTS ( OUT OF 50)

PUS CELLS

13

RBCS

8

EPITHELIAL CELLS

6

The most frequent finding in urine examination is presence of pus cells.

(F) SENSITIVITY AND SPECIFICITY OF MDCT IN DIAGNOSING MALIGNANT LESIONS OF URINARY TRACT

TEST

MALIGNANT

NON MALIGNANT

POSITIVE

12 (true positive)

1 (false positive)

NEGATIVE

1 (false negative)

36 (true negative)

SENSITIVITY = (12 x 100)/ (12 + 1)

= 92.3%

SPECIFICITY = (36 X 100)/ (36 + 1)

= 97.2%

DISCUSSION

It was observed that though in a few cases, ultrasound was to lead to the final diagnosis in patient, MDCT with different protocols definitely provided valuable additional information to guide to the uroradiodiagnosis.

In the present study:

The maximum numbers of patients were of the age 50-70 years with almost equal number of males and females.

The most common presenting complaint was abdominal pain followed by fever.

Lesions to which various basic pathologies were assigned in this study according to their MDCT appearances include:

BENIGN NEOPLASM : lipoma, Angiomyolipoma

MALIGNANT NEOPLASM : malignancies of kidney, ureter or bladder (most commonly TCC) and renal metastases

CONGENITAL: PCKD, horse shoe kidney, malrotation, ectopic kidney, renal agenesis, duplex PC sytem, PUJ obstruction

VASCULAR : renal artery stenosis, hypoplastic renal artery, renal vein thrombosis

OBSTRUCTIVE: HDN, pyonephrosis, urinoma( gen. post-obstructive)

INFECTIVE: acute pyelonephritis, emphysematous pyelonephritis, chronic pyelonephritis, cystitis, infective collections

MISCELLANEOUS: vesicovaginal fistula

No sex predilection was noted in infective pathologies.

More number of females had benign pathologies as compared to males.

However in case of malignancies, the number of males were almost double the number of females.

In all cases of malignant neoplasm, MDCT provided vital information regarding the extent, vascularity (in form of enhancement), abutments and infiltration of the pathology and hence helps in staging.

The portal venous and venous phases were helpful in diagnosing upper urinary tract tumors whereas delayed and full bladder phases provided important additional information in ureteric and bladder malignancies.

In the present study , the sensitivity and specificity of MDCT for diagnosis of malignant pathologies (primary and metastatic) were 92.3% and 97.2% respectively.

This is in concordance with the study performed by Max Kupershmidt, Myles Margolis, Hyun-Jung Jang etal in the Mount Sinai Hospital and Women's College Hospital, Toronto, Canada found that the detection rate of the proximal two upper urinary tract segments was significantly higher than that for the distal segments (p < 0.001) and sensitivity, specificity, and negative predictive value of portal venous phase MDCT were 95%, 97%, and 100%, respectively.

It confirms the presence of fat in the lesion on the basis of density in hounsefield units and hence helps in the diagnosis of lesions like lipoma and Angiomyolipoma.

In the present study , most cases with vascular pathologies were under diagnosed or missed on ultrasound due to difficulty in visualisation of vessels because of bowel gas.

In "vascular" lesions i.e. renal artery stenosis, renal vein thrombosis, accessory renal arteries etc., the MIP images outline the vessels in entire extent and helping characterization of the lesion and assessment of severity. Hence we found that MDCT is a good noninvasive imaging technique for the evaluation of renal vessels.

This observation is supported by the study "Arteriographic correlation in 30 patients with renal vascular disease diagnosed with multislice CT " done by AU Echevarría JJ, Miguélez JL, López-Romero et al which proved that it had a sensitivity of 96.5%, specificity 78.5% when compred with DSA.

In case of " congenital" pathologies, the most common was polycystic kidney disease (3 out of 9) followed by malrotation of entire kidney or one of its pole and renal agenesis. Most patients with congenital pathoogies were asymptomatic and hence detected incidentally on ultrasound or MDCT.

The study "Congenital renal anomalies detected in adulthood" in the Biomedical Imaging and Intervention Journal , Thailand compared abdominal radiograph, IVP, RP, US and CT and concluded that CT was the best imaging modality to evaluate anatomy, function and complications of patients with renal anomalies. However the most frequently encountered pathology in this study was horse shoe kidney but in present study is polycystic kidney disease.

In this study two cases of URINOMA were diagnosed in which ultrasound could only demonstrate evidence of collection. However, MDCT in delayed phases showed extravasation of contrast within the collection and hence we clinched the diagnosis.

A variety of lesions can present as multiple hypoechoic areas in kidneys on ultrasound. However, MDCT aids in diagnosing renal abscesses on the basis of peripheral enhancement with or without central necrotic areas.

MDCT plays pivotal role in differentiation of a hypoplastic kidney from one affected with chronic pyelonephritis.

As in this study the patients with only urinary tract calculi were excluded from the study , we observed that in patients with non calculus causes of obstruction, the actual etiology (extraluminal, intramural, intraluminal) was well delineated.

CONCLUSION

Hence through this study we conclude that:

MDCT has an important role in uroradiodiagnosis for detection of urinary tract pathologies, to ascertain various radiological features and categorize lesions in congenital, infective, vascular or neoplastic condition and evaluate extent of disease process.

In a wide variety of pathologies, MDCT provides vital additional information that helps to clinch the final diagnosis.

It is not affected by factors like obesity or excessive bowel gas which are a hindrance for sonographic diagnosis.

One of the major drawbacks is the radiation exposure, and hence we need to weigh it against the advantages offered by the modality and strictly employ protocols tailored to the patients complains and the suspected pathology.

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