40 Intra-Articular Masses on Magnetic Resonance Imaging

CLINICAL IMAGAGINGAN ATLAS OF DIFFERENTIAL DAIGNOSIS

EISENBERG

DR. Muhammad Bin Zulfiqar PGR-FCPS III SIMS/SHL

• Fig B 40-1 Lipoma arborescens. (A) Sagittal proton density-weighted image shows a lobulated mass in the suprapatellar bursa (arrow) with signal intensity equivalent to that of fat. (B) A fat-saturation sequence shows loss of signal of the synovial proliferation (arrow) surrounded by a large joint effusion extending into the popliteal bursa (*).48

• Fig B 40-2 Synovial osteochondromatosis. (A) Coronal proton density-weighted image demonstrates an intermediate-signal-intensity mass (*) in the radioulnar joint. (B) Coronal T2-weighted image shows that the mass (*) is hyperintense. On both MR images, note the multiple low-signal-intensity areas (arrowhead) representing regions of calcification that were evident on plain radiographs.48

• Fig B 40-3 Synovial osteochondromatosis. Sagittal proton density-weighted image demonstrates calcified nodules as masses of low signal intensity (arrow) in the deep infrapatellar bursa.48

• Fig B 40-4 Diffuse PVNS. Sagittal proton density-weighted image shows lobulated, mass-like synovial proliferation with characteristic low signal intensity. Note the tibial articular erosions.48

• Fig B 40-5 Focal PVNS. Sagittal proton density-weighted image shows a low-signal-intensity mass (arrow) in the anterior joint space.48

• Fig B 40-6 Rheumatoid arthritis. A sagittal T1-weighted image shows a low-signal-intensity lesion (*) in the talus, with low-signal-intensity pannus (arrows) in the joint space.48

• Fig B 40-7 Tuberculous arthritis. (A) Coronal T1-weighted image of the right shoulder demonstrates an erosion of the humeral head (arrowhead) and a distended joint space with proliferative synovium (arrow). Note the adjacent large mass (*). (B) On a T1-weighted contrast study with fat saturation, the mass (*) appears as a fluid-filled collection with an enhancing periphery rather than a solid tumor. Note the enhancement of the synovium within the joint (arrow) and the marginal erosion (arrowhead). The combination of a destructive inflammatory arthritis decompressing into the adjacent subdeltoid bursa to form a cold abscess is typical of tuberculous arthritis.48

• Fig B 40-8 Coccidiodomycosis. (A) Coronal T1-weighted image demonstrates a joint effusion and marginal erosions of the proximal tibia with preservation of the joint spaces. (B) Axial proton density-weighted image with fat saturation demonstrates multiple rice bodies (arrow) within a joint effusion.48

• Fig B 40-9 Gout. Sagittal STIR image demonstrates low signal intensity of the gouty tophus (*). There is erosion with an overhanging edge at the distal head of the first metatarsal and preservation of the joint space.48

• Fig B 40-10 Klippel-Trenaunay-Weber syndrome. An axial T2-weighted image demonstrates a joint effusion (*) and an intermediate-signal-intensity AVM in the suprapatellar bursa with a prominent serpentine signal void (arrow) from a large feeding artery. Note the large, dilated superficial veins (arrowheads).48

• Fig B 40-11 Synovial hemangioma. Sagittal proton density-weighted image with fat saturation demonstrates a mass in the suprapatellar bursa that invades the musculature anteriorly (arrow). The markedly high signal of the mass reflects pooling of blood within the vascular spaces of this synovial hemangioma.48

• Fig B 40-12 Synovial hemangioma. (A) Axial T1-weighted image shows an intermediate-signal-intensity lesion in the suprapatellar pouch (arrow) containing areas of high signal intensity. (B) Corresponding fat-suppressed T2-weighted image shows a characteristic circular-linear pattern (arrow) that probably represents fibrous septa or vascular channels traversing the lesion.49

• Fig B 40-13 Synovial sarcoma. Sagittal contrast T1-weighted image with fat saturation demonstrates enhancement of a mass (arrow) in the anterior joint space of the knee. Note the foci of low signal intensity, which persisted on all pulse sequences, consistent with areas of calcification.48

• Fig B 40-14 Synovial chondrosarcoma. (A) Axial T1-weighted image demonstrates a large, lobulated, low-signal-intensity mass (*) distending the knee joint space, with erosions and invasion of the femoral condyles (arrows). (B) Axial T2-weighted image obtained more distally demonstrates high signal intensity (*) within the mass.48

• Fig B 40-15 Cyclops lesion. Sagittal T2-weighted image following anterior cruciate ligament reconstruction demonstrates a mass anteriorly in the joint space of the knee. Note the characteristic low signal intensity of this fibrous mass (arrow).48