Solid Processes RCC-invasion of perirenal fat, thickening of renal fascia. Renal cell carcinoma is the most common malignancy of the kidney and accounts for 2% of all cancers. Lymphoma - multiple renal masses, contiguous retroperitoneal masses, perirenal masses, single renal mass Metastasis - to perirenal lymphatics - melanoma, RCC, lung (via pleura/mediastinal connections) Fibrosis - AO, IVC, ureters, perinephric space Amyloidosis - perirenal soft tissue collections Renal cell carcinoma (RCC) • is the most common primary renal malignant neoplasm in the adult. It accounts for approximately 85% of renal tumors and 2% of all adult malignancies. • RCC is more common in men than in women (ratio, 2:1), and it most often occurs in patients aged 50-70 years. • One fourth to one third of patients have metastatic disease at the time of presentation. • In only approximately 2% of sporadic cases are bilateral tumors seen at presentation. RCC risk factors include • increased age, male sex, smoking, cadmium, benzene, trichloroethylene and asbestos exposure, excessive weight, chronic dialysis use, and several genetic syndromes (familial RCC, hereditary papillary RCC, von Hippel-Lindau syndrome, and tuberous sclerosis) Renal Cell Carcinoma with Spread to Gerota’s Fascia MRI of the Kidneys When contraindication to IV contrast Renal mass characterization Staging renal cell carcinoma Vascular involvement Renal cell carcinoma MRI better than CT in demonstrating vascular invasion – Renal vein – IVC Tumor Tumor Coronal Axial Renal Cell Carcinoma with tumor invading right renal vein and IVC Tumor Axial Retroperitoneal Lymphoma Lymphadenopathy - can directly invade kidney or encase ureter Perirenal involvement - transcapsular, direct spread from lymph nodes, isolated disease (least common) Lymphoma - Direct invasion of kidneys Perirenal Lymphoma Bilateral Perirenal Lymphoma Lymphoma involving the small bowel mesentery, anterior pararenal space, perinephric space and kidneys Metastatic Lung Cancer Perinephric Metastasis Adrenal Metastasis Renal Infarction Causes – – – – Embolism (cardiac) Aortic dissection Trauma Venous thrombosis (dehydration, tumor) Renal Infarction CT Findings (with IV contrast) Focal – Region of no enhancement Diffuse – Hypodense kidney – Renal enlargement May see rim of enhancement – Patent collateral capsular vessels Two contrast-enhanced axial CT images demonstrate a wedgeshaped non-enhancing lesion in the right kidney with no perinephric inflammatory stranding History atrial fibrillation, presents with right flank pain Left atrial thrombus Renal infarct Right Flank Pain Renal tumor IVC Renal infarct Presents with left flank pain Pyonephrosis — gas in infected collecting system Patient Presents with Right Flank Pain Kidney normal Cholecystitis Gallstone in distended GB 2 Different Patients with Right Flank Pain Dermoids Ovarian cyst CRF: Prominent bridging septae and small amount of perinephric fluid Kidney “sweat sign” Fluid in perirenal space corresponding to thickened septae and fluid on CT scan Echogenic kidneys in patient with CRF Acute Pancreatitis Inflammatory process spares perinephric spaces Acute hemorrhage in anterior pararenal space involves perinephric space via septae Lymphatic Spread of Disease from Perinephric Space •Small perirenal lymph nodes Nodes in renal hilum Periaortic/pericaval nodes Inflammatory Processes and Fluid Collections Infections Urinomas Hematomas Pseudocysts Infections Most originate from kidney May spread through all spaces and via bare area to peritoneum and thorax Xanthogranulomatous pyelonephritis Subcapsular Abscess Chronic Perinephric Abscess Abscess is loculated in perinephric space secondary to perinephric septae. See also calculus and mild hydronephrosis Pyelonephritis in Ectopic Kidneys Adrenal Level Renal Level Note straight adrenal glands with liver, spleen and colon falling into expected renal fossae. At level of pancake kidney, renal fascia is visualized and slightly thickened. Perinephric gas extending to extraperitoneal space and to anterior abdominal wall muscles. Patient with fever after left hemicolectomy Xanthogranulomatous Pyelonephritis Obstructed upper pole Extension to post pararenal space and post abd wall Perinephric Collection Hematomas Traumatic- MVA, iatrogenic Spontaneous- tumor, vascular (AAA, AVM, arteritis), hematologic disorders, endstage kidney Spread of hepatic or splenic hematomas to perinephric space without renal injury Leaking aortic aneurysm Subcapsular into anterior pararenal space extending along iliac vessels into pelvis. Also via perinephric septae to upper aspect post pararenal space Spontaneous Hemorrhage in End-stage Kidney Subcapsular to perinephric to anterior pararenal hematoma secondary to renal artery stent placement ATN with vicarious gallbladder excretion Renal Cell Carcinoma with spontaneous hemorrhage Traumatic Avulsion Renal Artery RRA with perinephric hematoma Retroperitoneal Fibrosis Most commonly idiopathic Other causes: aortic hemorrhage, aortitis, methysergide toxicity, prior surgery or XRT, collagen vascular disease (Riedel’s thyroiditis, sclerosing mediastinitis) Clinical: 40-60 yrs, males>females Hydronephrosis, ureteral narrowing, slight medial ureteral displacement Retroperitoneal Fibrosis Retroperitoneal Fibrosis extending into perinephric and postpararenal spaces MRI of the Adrenal Glands Metastases versus non-functioning adenoma Suspected pheochromocytoma Helpful to localize origin of mass discovered on CT/US – Upper pole kidney vs adrenal gland Is this mass arising from the liver, kidney or adrenal gland? Coronal imaging shows mass not renal in origin Adrenal tumor invading liver Adrenal Masses Adenomas are very common – 2-8% of population Metastases are common in adrenal glands Fortunately, MR can accurately distinguish between adenomas and metastases Adrenal Adenomas Key to diagnosis is demonstrating fat/lipid in mass Chemical shift imaging Fat suppression imaging MRI of adrenal adenomas High lipid content Chemical shift imaging helpful – In-phase: bright – Out-of-phase: dark Look for “india ink” rim at fat/water interface In-phase image Out-of-phase image Abdominal Aortic Aneurysm Without rupture may present as pulsatile abdominal mass without pain With rupture, typically present with back pain or mid abdominal pain CT Diagnosis of AAA Rupture Retroperitoneal hematoma Contrast extravasation High density crescent Calcified rim of aorta is discontinuous Discontinuous aortic wall Contrast extravasation A retroperitoneal hematoma Abdominal Aortic Dissection Defined as hematoma in wall, typically with intimal tear CT is screening modality of choice Acute aortic dissection is most common aortic emergency Helical CT with sensitivity and specificity near 100% Considered acute if sx < 2 weeks, chronic if longer 75% deaths occur within 2 weeks of initial sx Hypertension is major cause adding mechanical stress to aortic wall with longitudinal shearing forces and decreased vasa vasorum flow increases stiffness of media causing more stress and contributing to development of dissection Abdominal Aortic Dissection CT Diagnosis Contrast in 2 channels – If one lumen thrombosed difficult to differentiate from mural thrombus Intervening intimal flap 1 2 1 2 Pt presented with flank pain, had unenhanced CT Calcified intimal flap displaced medially from wall of aorta Contrast demonstrates 2 lumens Penetrating Atherosclerotic Ulcer Ulceration of atheromatous plaque that erodes inner, elastic layer of aortic wall and when it reaches medial layer, media is exposed to arterial flow, causing hemorrhage in wall. Localized dissection can occur, break into adventitia, resulting in PSA or rupture CT Findings Unenhanced: extensive atherosclerosis, focal and variable IMH, displaced intimal calcification Enhanced: Collection of contrast visualized outside lumen, similar to peptic ulcer. May be multiple or single with thickening of aortic wall. Atheromatous ulcers confined to intima may be seen in asymptomatic patients, but should be followed for progression to aortic aneurysm. When rupture occurs, impossible to differentiate from ruptured aneurysm. Unenhanced CT with IMH, enhanced CT at same level shows ulcer filled with contrast Castaner True lumen of celiac trunk and left renal artery narrowed by thrombosed false lumen. Left renal infarction