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GUT CASE INVESTIGATION. LECTURE 1. Nephrolithiasis(renal stones). Epidemiology Up to 10% by age 70, usu in 3 rd to 4 th decade 4:1 M to F ratio More prevalent in the South Risk Factors

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    2. Nephrolithiasis(renal stones) • Epidemiology • Up to 10% by age 70, usu in 3rd to 4th decade • 4:1 M to F ratio • More prevalent in the South • Risk Factors • Hypercalcemic states, Crohn’s, stents, RTA, infection, gout, hypercalciuria, hyperuricosuria, cystinuria • Symptoms • Asymptomatic, flank pain, hematuria

    3. Composition OPAQUE contains calcium +/ phosphate • Calcium calculi • Ca oxalate, Ca phosphate • Struvite calculi • Magnesium ammonium phosphate= triple phosphate SEMI OPAQUE contains sulphur • Cystine calculi LUCENT • Uric acid stones;Xanthine • Matrix (coagulated mucoid material)

    4. CT Imaging of Stones • Essentially all renal and ureteral calculi have high attenuation on non-contrast CT(all but matrix stones have atten of > 100HU) • CT has sensitivity of 97% and specificity of 96% • Can also see hydronephrosis, hydroureter, renal enlargement, or perirenal stranding • Must differentiate from phlebolithwhich is a calcified blood clot in a pelvic vein.(appearance: round/ovoid, smooth, central lucency, in true pelvis)

    5. Nephrolithiasis Radio opaque stone in calyx Images: BIDMC, Dept of Radiology, 2001.

    6. Hydronephrosis Dilated urine filled pelvis Stent

    7. Hydroureter Stent Images: BIDMC, Dept of Radiology, 2001.

    8. Obstructive Uropathy Radiologic Assessment

    9. Anatomy: Urinary Tract Renal Capsule Calyx Superior Operculum Cortex Medulla Papilla Pelvis Inferior Operculum Fornix

    10. Unequivocal Obstructive Uropathy = Urinary tract obstruction Unequivocal: clear etiology • Obstruction may be at any site within GU tract • Evidence of post-renal failure • Variable presentation based on etiology Sign: Hydronephrosis = dilatation of renal pelvis and ureters

    11. Pathophysiology of Obstructive Uropathy Hydronephrosis Mechanical or functional obstruction Back up of urine flow = increased renal pressure Tubular dilatation Initial increase in renal blood flow Decrease in renal blood flow Increase in renal lymphatic flow Initial increase in ureteral peristalsis & pelvic muscle hypertrophy Muscle stretched & atonic  Aperistalsis Dilatation of ureters and renal collecting duct system Parenchymal Atrophy Renal failure Pathogenesis of unilateral hydronephrosis. Smith’s Urology p.181

    12. How Acute Obstruction leads to Dilatation and Decreased Tubular Function

    13. Pathology Dilated pelvis & calyces, renal atrophy, cut surface Dilated renal pelvis (arrow), external view

    14. Clinical Presentation: Obstructive Uropathy Lower and Mid Tract (Urethra and Bladder) Upper Tract (Ureter and Kidney) Renal insufficiency Consider UTO in all patients with unexplained renal insufficiency Urine Output Changes Anuria = complete bilateral UTO Partial obstruction  normal to elevated UO Hyperkalemic renal tubular acidosis Hypertension Lab Abnormalities: normal, microscopic/gross hematuria, pyuria, azotemia, uremia, anemia (2/2 chronic infection, ACD), leukocytosis Hesitancy in starting urination Lessened force Weak stream Terminal dribbling Hematuria Burning on urination Cloudy urine (infection) Acute urinary retention Flank pain radiating along ureter course (distension) Gross hematuria Nausea/Vomiting Fever/Chills Burning on urination Cloudy urine with infection Bilateral uremia N/V/weight loss

    15. Think Anatomically: Where is obstruction? Proximal etiology Unilateral hydronephrosis Series: 53 of 380 patients 52/53 in lower 1/3 of the ureter. Causes: Ureteral stones 64% Ureteral edema or lucent stones 30% Neoplasms 4% Inflammatory disease 2% Most Common in Distal Ureter Systemic or Distal etiology Bilateral hydronephrosis Chen et al., J Emerg Med, 1997: 15; 3. 339 – 343.

    16. Acute Obstruction and Anuria Acute complete, bilateral obstruction = Medical Emergency Patients may die from acute renal failure with oliguria/anuria Requires prompt recognition and possible surgical intervention CT examination: Postcontrast axial scan: The retroperitoneal giant tumor mass compresses the right ureter and causes hydronephrosis (arrows).

    17. Diagnosis Early diagnosis and decompression is critical to prevent renal failure Continue to Radiologic work-up

    18. Ultrasonography Test of Choice for Suspected Urinary Tract Obstruction Screening test Indications: Renal failure of unknown origin/Hematuria/Signs of UTO/Urolithiasis Sensitivity for detection of chronic obstruction: 90% Sensitivity for detection of acute obstruction: 60% Advantages: No allergic/toxic complications of radiocontrast media Fast, inexpensive Diagnose other causes of renal disease in patient with renal insufficiency of unknown origin Polycystic Kidney Disease Disadvantages Nonspecific Rarely identifies cause False positive rate: < 25% with minimal criteria (operator dependent) Any visualization of collecting systems False negative with acute obstruction, dehydration, sepsis Bowel Gas decreases sensitivity

    19. Ultrasound – Normal Kidney Normal renal parenchyma, hypoechoic, normal function Normal renal fat, no dilatation of collecting system, hyperechoic

    20. Ultrasound – Obstructive Uropathy Renal parenchyma, hypoechoic Dilated collecting duct, hypoechoic (fluid) Compressed renal fat, hyperechoic

    21. CT: normal renal parenchyma with proximal stone, no obstructive uropathy Noncontrast CT Enhancing calculus in interpolar portion of R Kidney Kawashima et al., RadioGraphics 2004;24:S35-S54

    22. CT: Hydronephrosis due to retroperitoneal fibrosis (soft tissue) CT (postcontrast): Giant retroperitoneal tumor mass compressing the right ureter, causing hydronephrosis with compression ofrenal parenchyma(arrows).

    23. CT: Obstructive Uropathy Dilated Renal Pelvis Proximal Stone CT (postcontrast): Obstructive left-sided uropathy with proximal ureteric stone PACS, Courtesy of Dr. D. Brennan

    24. IVU: Intravenous Urogram Intravenous Pyelogram = Excretory Urogram • Scout film  calculi? • IV bolus of radiocontrast dye (ionic contrast) • Series of plain films demonstrate kidneys, ureters, urinary bladder 4. Upright film post-void to evaluate for obstruction Advantages Anatomy Pathology Location Rough indicator of function bilaterally Low false positive rate Detects associated conditions Papillary necrosis  intralumenal filling defect Caliceal blunting from previous infection Disadvantages Cumbersome Requires radiocontrast Need bowel prep with conventional IVU Radiation dose Need cross-sectional imaging follow up

    25. CT Urography Evaluate urinary tract for flow defects Noncontrast Scout first: Urolithiasis Coronal reconstructions: visualize entire urinary tract • Advantages over Conventional IVU • Speed • Sensitive to renal parenchyma abnormalities • Simultaneous evaluation of both renal parenchyma and urinary tract • Cross-sectional imaging • Disadvantages • Radiation dose • Ionic Contrast reactions/cannot be used in patients in renal failure Kawashima et al., RadioGraphics 2004;24:S35-S54

    26. Normal CT Urogram CT Urography Total Body Opacificantion Nephrogram Pyelogram

    27. Normal CT Urogram CT Urography Total Body Opacificantion Nephrogram Pyelogram

    28. Normal CT Urogram CT Urography Total Body Opacificantion Nephrogram Pyelogram

    29. Normal CT Urogram CT Urography Total Body Opacificantion Nephrogram Pyelogram

    30. Normal CT Urogram CT Urography Total Body Opacificantion Nephrogram Pyelogram Pt. JL, PACS, Courtesy of Dr. AC Kim

    31. Normal CT Urogram CT Urography Total Body Opacificantion Nephrogram Pyelogram

    32. Normal CT Urogram CT Urography Total Body Opacificantion Nephrogram Pyelogram

    33. Contraindications for IVU/CTU History of allergy to IV contrast Bronchospasm, laryngeal edema, anaphylactic shock May use with history of minor allergic reactions with preprocedural steroids, antihistamines (diphenhydramine) 12 hours prior to study Renal insufficiency Pregnancy = relative contraindication (radiation exposure) MR Urogram can be used Likewise: children  minimize radiation doses Pts taking oral hypoglycemics (metformin) should stop taking meds prior to study May resume after renal function is confirmed normal Risk of lactic acidosis Must be Physician-Supervised - Contrast reactions - Minimize no. of images - Minimize radiation - May use Fluoroscopy

    34. MR Urography Sagittal contrast-enhanced excretory MR urography obstructing right sided papillary TCC A. Unenhanced MR urography Heavily T2 weighted B. Gadolinium-enhanced excretory MR urography C. Excretory MR urography + diuretic 10 mg furosemide IV Gadopentetate dimeglumine Advantages: Distinguishes adjacent soft tissue abnormalities With Gadolinium: functional information No ionic contrast  OK in renal failure No radiation  children, pregnancy women Drawbacks High cost Low sensitivity in detecting calcifications Time intensive Metallic implants/Foreign Body = Contraindications Blandino et al., AJR 2002; 179: 1307 -1314

    35. Excretory Urogram/CTU/MRUAcute Obstruction Mild  Moderate  Marked • Kidney minimally enlarged • Dense Nephrogram • Preferential absorption of Na and water from diseased tubules = concentration of contrast • Delayed appearance of contrast in collecting system • = delayed function • Poor concentration of contrast in the collecting tubules • No ureteral dilatation acutely • Ureters not tortuous

    36. Excretory Urogram/CTU/MRU Chronic Obstruction Partial  Complete Calyceal Clubbing Progressive dilation of collecting system and ureters/tortuous Urectasis = dilated ureter Decrease number of nephrons 6-12 weeks: irreversible loss of renal function “Shell nephrogram” parenchymal atrophy Collecting system: blunt calyces/forniceal angles Blandino et al., AJR 2002; 179: 1307 -1314

    37. Patient JL – Bladder Mass Diagnosis: 57 yo M with known Bladder CA with left hydronephrosis secondary to left bladder cancer. Management Foley placement for immediate decompression. Pt urinated following catheter removal and was cleared for d/c Urology consult for possible stent placement Left Bladdermass surrounding UO

    38. Renal Cystic Disease • Very common 50% of pts over age of 50 • Assoc w/ many syndromes, etiology unknown, probably arise from obstructed tubules or ducts • Most commonly asymptomatic • Rarely, may have hematuria, HTN, cyst infection, or mass effect

    39. CT Characteristics of Simple Cysts • Smooth, imperceptible cyst wall • Sharp demarcation from surrounding renal parenchyma • Water attenuation (<15 HU), homogenous throughout lesion • Non-enhancing • Simple cysts are w/o septations or calcification • May have slight elevation of adjacent renal parenchyma  Beak sign

    40. Type I Simple Cyst Bird Beak Sign Aortic aneurysm Inferior vena cava with filters Simple Cyst Images: BIDMC, Dept of Radiology, 2001.

    41. Type IV Cystic Neoplasm Complex renal mass infiltrating lvc Images: BIDMC, Dept of Radiology, 2001.

    42. Conditions Associated with Multiple Cysts • Autosomal Dominant PCKD • Autosomal Recessive PCKD • Acquired Cystic Disease (hemodialysis pts) • Von-Hippel-Lindau disease • Tuberous Sclerosis • Medullary Sponge Kidney

    43. Benign Masses • Cysts • Angiomyolipoma • Oncocytoma (via epithelial cells of prox tubule) • Renal Adenoma • Mesoblastic Nephroma (hamartomatous tumor, usu present at birth) • Hemangioma • Various Renal Pelvic Tumors(papilloma, angioma, fibroma) • Hematoma

    44. Angiomyolipoma • Hamartomas containing fat, smooth muscle, and blood vessels • Usually asymptomatic, but may spontaneously bleed • Large AMLs resected or embolized • Multiple AMLS usually Associated w/ tuberous sclerosis • On CT *fat attenuation in mass*, strong contrast enhancement (RCCs rarely contain fat), no Ca2+

    45. Angiomyolipoma Note fat content Images: BIDMC, Dept of Radiology, 2001.

    46. Malignant Masses • Renal Cell Cancer • Transitional Cell Cancer • Wilm’s Tumor • Nephroblastomatosis (multiple rests of embryologic metanephric blastoma) • Lymphoma • Metastases (lung, breast, colon, melanoma)

    47. Renal Cell Ca • Most common primary renal malignancy (85% of primary renal tumors) • Assoc w/ smoking, family hx, age, Von Hippel-Lindau, Acquired Cystic Disease/chronic dialysis, phenacetin abuse • Presentation: Hematuria, flank pain, wt loss, palp mass, fever, anemia, paraneoplastic syndromes • liver enzymes w/o mets Stauffer syndrome

    48. CT characteristics • Variablefrom complex cyst to large, heterogeneous renal mass • Generally enhancing • May have calcifications • May have hemorrhage and central necrosis • Usually no fat

    49. Renal Cell Ca Images: BIDMC, Dept of Radiology, 2001.

    50. RCC Images: BIDMC, Dept of Radiology, 2001.