CT & MRI of Benign Liver Neoplasms Srinivasa R Prasad

Transcription

1 CT & MRI of Benign Liver Neoplasms Srinivasa R Prasad No financial disclosures

2 Acknowledgements Many thanks to Drs. Heiken, Narra & Menias (MIR) Dr. Sahani (MGH) for sharing images

3 Benign Liver Tumors: Introduction Common incidentalomas in asymptomatic patients Broad pathologic spectrum with variable behavior Misdiagnosed as cancer Characteristic imaging characteristics Accurate characterization essential for management Therapeutic & prognostic implications

4 Benign Liver Neoplasms: 2000 WHO Taxonomy Epithelial Neoplasms Hepatocellular Adenoma Focal Nodular Hyperplasia Intrahepatic Bile Duct Adenoma, Cystadenoma Biliary Papillomatosis Biliary Hamartoma Non-Epithelial Neoplasms Hemangioma Miscellaneous Neoplasms Solitary Fibrous Tumor Lymphangioma & Lymphangiomatosis Teratoma Angiomyolipoma

5 MDCT for Liver Imaging MDCT permits short breath-hold, multi-phase, high-resolution liver scanning Improved z-axis coverage, excellent spatial resolution, fast scanning & thin-slice acquisition Isotropic images and less helical artifacts allow superior multi-planar & 3D reformations

6 MDCT for Liver Imaging MDCT allows consistent, uniform vascular & parenchymal enhancement Better detection & accurate localization of liver tumors 3-D CT angiography & parenchymal images provide useful pre-operative road-map to surgeons

7 150 cc 370 mg non-ionic iodinated 5 cc/sec cc/kg body weight 16-MDCT Dual Phase Liver Protocol Parameters Arterial Venous Detector 16x x0.625 Configuration (mm) Table feed mm/sec Pitch Slice Thickness (mm) Delay Arterial Bolus track /automated trigger Delay Venous (sec) sec

8 MRI for Liver Imaging Recent advances in magnet design, hardware & software allow short breath-hold, multi-phase liver imaging No significant peristaltic & respiratory motion artifacts & faster 3-D imaging sequences improve MPRs Feasible to obtain tissue-specific images; use of Gdcontrast permit accurate lesion detection, localization & characterization

9 MRI for Liver Imaging: Gadolinium-Chelate Pre-contrast FSE T2, in & opposed phase GRE-T1 Triphasic dynamic acquisitions Arterial phase 30 seconds Portal phase seconds Equilibrium phase 3-5 minutes Pulse sequence Breath-hold imaging with or without fat saturation Multislice Spoiled Gradient Echo technique (FMSPGR; FLASH)

10 MRI Contrast Agents: Gd-EOB & Gd-BOPTA Both Gd chelates show both extracellular fluid space distribution & selective hepatocellular uptake Permit long-lasting liver enhancement as well as dynamic effects of Gd chelates

11 Hepatocellular Adenoma: Introduction Benign hepatocellular tumor; young women on oral contraceptives & anabolic steroids Patients with glycogen storage disease type 1 Liver cords/sheets separated by sinusoids Dilated sinusoids with scanty connective tissue support: Predilection to hemorrhage/rupture? increased risk of malignant change to HCC

12 Hepatocellular Adenoma: Imaging synopsis Heterogeneous tumor due to steatosis, necrosis & hemorrhage Hypervascular tumor with predisposition to hemorrhage Presence of microscopic fat: Characteristic feature

13 Adenomatosis: : Imaging synopsis Adenomatosis: Multiple (>10), symptomatic adenomas in normal liver Complications: Altered liver function, hemorrhage, & malignant change

14 Focal Nodular Hyperplasia: Introduction Second most common benign tumor; asymptomatic young women (3 rd -4 th decades) Solitary; multiple FNHs seen with vasc. anomalies Liver nodules with malformed vessel/biliary network Stealth tumor; easily missed in portal venous phase

15 Focal Nodular Hyperplasia: Imaging Synopsis Isodense (isointense) to the liver on pre/portal phase T2-Hyperintense (hypodense) central scar that shows delayed enhancement CT/MRI dynamic enhancement pattern Intense arterial enhancement (rich capillary network) Isodense (-intense) to liver on portal venous phase

16 Biliary cystadenoma: : Introduction Rare cystic tumor with mucinous & serous subtypes Exclusively in women; complex cyst with enhancing septations, calcifications; fluid-fluid levels Polypoid/papillary mural nodule; malignant change

17 Liver Hemangioma: : Introduction Most common mesenchymal tumor; F:M=5:1 Solitary, well-circumscribed, subcapsular lesion Endothelium-lined blood channels; variable thrombosis Sclerosed variant: Thick-walled vessels & fibrosis

18 Liver Hemangioma: : Imaging Synopsis CT density (pre- & post contrast) follows the aorta Peripheral nodular enhancement, progressive centripetal contrast fill-in : Pathognomic finding CT/MRI dynamic enhancement pattern Comes early, leaves late ( Mother-in-law sign)

19 Liver Hemangioma: : Imaging Synopsis Hyperintense on heavily T2-W MRI Peripheral nodular enhancement, progressive centripetal contrast fill-in : Pathognomic finding CT/MRI dynamic enhancement pattern Comes early, leaves late ( Mother-in-law sign)

20 Angiomyolipoma: : Introduction Rare, triphasic mesenchymal tumor; PEComas Solitary; multiple AMLs-Tuberous sclerosis Fat & prominent vessels : characteristic findings Absence of fat in up to 50% liver AMLs Trabecular variant: presence of intracellular fat

21 Hemorrhagic Liver Neoplasms Hepatocellular Adenoma Hepatocellular Carcinoma Hemorrhagic Metastases (Choriocarcinoma)

22 Fat-containing Liver Neoplasms Benign tumors with macroscopic fat Angiomyolipoma, Hepatocellular Adenoma, Lipoma (uncommon), Adrenal Rest Tumor (rare), Teratoma (rare) Benign tumors with microscopic fat Hepatocellular Adenoma, Angiomyolipoma (rare; trabecular variant), Focal Nodular Hyperplasia (rare) Malignant tumors with macroscopic fat Hepatocellular Carcinoma, Metastases (typically Liposarcoma, Clear cell RCC)

23 Hypervascular Liver Neoplasms Homogenous contrast enhancement Benign: Hemangioma (small), FNH, Adenoma Malignant: HCC (small), Hypervascular metastases, Angiosarcoma Heterogeneous contrast enhancement Benign: Hemangioma (large), Adenoma Malignant: HCC, Fibrolamellar HCC, Metastases, Epithelioid Hemangioendothelioma