Osamu Karakida

MR of enchondroma and chondrosarcoma: rings and arcs of Gd-DTPA enhancement.

MR studies of five chondrosarcomas and three enchondromas were performed with intravenous Gd-DTPA administration. All tumors showed enhancement of scalloped margins and curvilinear septa (ring-and-arc pattern) on T1-weighted SE sequences with Gd-DTPA. On radiologic-pathologic correlation, the enhanced areas corresponded to fibrovascular bundles surrounding hyaline cartilage lobules. The rings and arcs of enhancement with Gd-DTPA on MR is a reflection of the lobulated growth pattern of cartilaginous tumors and therefore helpful in differential diagnosis of bone tumors.

Intraosseous neurilemmoma of the fibula

Abstract We present a case of intraosseous neurilemmoma of the fibula in a 56-year-old woman. This case showed the typical radiographic appearance except for the presence of spotted calcifications that mimicked a cartilaginous tumor. Enhanced MR images revealed the heterogeneity of the tumor, which consisted of Antoni type A and B tissue.

Giant cell tumors of bone containing large amounts of hemosiderin: MR-pathologic correlation.

We present three giant cell tumors of bone that contained large amounts of hemosiderin and compare their MR appearance with intraoperative findings and histological characterization. Histologically, hemosiderin was found in multinucleated giant cells, mononuclear stromal cells, and xanthoma cells. All cases showed markedly decreased signal areas on both T1- and T2-weighted MR imaging due to hemosiderin deposition; this made evaluation of the integrity of the adjacent cortices difficult. In one case, extraosseous tumor extension appeared as a signal void area on MR imaging. Findings on immunohistochemical studies suggested the giant cells may have a histiocytic nature. Because the tumor cells themselves have a phagocytic nature, the decreased signal areas in and around giant cell tumors should be regarded as active tumor tissues in delineating the tumor on MR imaging.

Epidural dumbbell-shaped chordoma mimicking a neurinoma

The authors present a case of cervical chordoma which manifested in a 5-year-old boy as a dumbbell-shaped epidural tumor without bone destruction. Both CT and MR1 demonstrated tumor features suggesting this diagnosis, which was confirmed by histology.

Ischiopubic insufficiency fractures: MRI appearances

Abstract Objective. To evaluate the MRI appearances in insufficiency fractures. Design. A retrospective analysis of spin echo MR images with gadolinium-enhancement was undertaken with the emphasis on the signal change and the shape of the fracture gap and the adjacent bone marrow. Patients. Five elderly women who had ischiopubic insufficiency fractures (pubis, 4; ischium 1) underwent MRI to exclude the possibility of pathologic fractures. Results and conclusions. In no case was contrast enhancement noted at the fracture gap or the adjacent bone marrow, but a cleft-life, elongated bright signal area suggesting “fluid collection” was noted within the fracture gap. Absence of contrast enhancement and “fluid collection” at the fracture gap might suggest nonunion of a fracture, which is additional information provided only by MRI.

Effect of disuse on bone mineral content, lean mass, and fat mass in osteoarthritic patients

Purpose: To evaluate the effect of disuse on bone mineral content (BMC), lean mass, and fat mass.Method and subjects: We obtained BMC, lean mass, and fat mass from measurements of each side of the arm and the leg in 20 women with unilateral hip osteoarthritis and 63 normal women using a whole-body dual-energy X-ray absorptiometry (DXA) scan. The ratio of the affected side to the unaffected side (A-U ratio) was calculated for BMC, lean mass, and fat mass in the arm and the leg.Results: A significant intergroup difference in the A-U ratio was noted for leg BMC (0.85vs 0.99,P<0.01), and for lean mass of the leg (0.88vs 0.99,P<0.01). When leg BMC was adjusted with lean mass, this intergroup difference became insignificant.Conclusion: This study reconfirmed that a decrease in BMC and lean mass can result from disuse. We suggest that a large portion of BMC loss in the immobilized leg might be a secondary change resulting from lean mass loss.

MR appearance of periosteal chondrosarcoma of the foot

Objective To assess the role of MRI in evaluating periosteal chondrosarcoma in the foot, an anatomically complicated location. Materials and Methods Three cases of surgically and histologically confirmed periosteal chondrosarcomas occurring in the foot (58-year-old woman, 57-year-old woman, and 63-year-old man) were retrospectively reviewed with an emphasis on MR findings. Results Magnetic resonance successfully delineated the hypovascular nature and lobulating pattern of the lesion suggesting the cartilaginous component, the periosteal location with sparing bone marrow, and the extent of involvement of adjacent structures. These findings were either not seen or less clearly seen on CT in the former two cases. Conclusion In cases of periosteal chondrosarcomas in the foot MRI can play a significant role both in the characterization of the lesion and in planning surgical therapy.

Role of magnetization transfer imaging in bone tumors.

RATIONALE AND OBJECTIVES The authors evaluated the role of magnetization transfer imaging in differentiation of bone tumors, with special emphasis on cartilaginous tumors. MATERIALS AND METHODS Fifty-one patients with skeletal tumors or tumor-like lesions who had undergone magnetic resonance (MR) imaging were included. The tumors were divided into three groups according to their gross appearance and the origin of tissue: cyst, cartilaginous tumor, and noncartilaginous solid tumor. A gradient-recalled acquisition in the steady state sequence was used for MR imaging, and examinations were performed both with and without off-resonance magnetization transfer pulses. Magnetization transfer ratios were obtained as an indicator of magnetization transfer effect of the lesions and were compared. Then, the magnetization transfer ratios of all tumors in the cartilaginous tumor group were compared. The magnetization transfer ratios of benign and malignant solid tumors were also compared. RESULTS The mean magnetization transfer ratio for cartilaginous tumors was 0.31 +/- 0.08 (standard deviation), and that of cysts and noncartilaginous solid tumors was 0.07 +/- 0.03 and 0.40 +/- 0.14, respectively. Comparisons between the three groups showed statistically significant intergroup differences in magnetization transfer ratio (P < .05). In the cartilaginous tumor category, enchondroma and low-grade chondrosarcoma had a lower magnetization transfer effect than chondroblastoma and mesenchymal chondrosarcoma. The mean magnetization transfer ratios of benign (n = 28) and malignant (n = 18) tumors were 0.35 +/- 0.11 and 0.39 +/- 0.15, respectively; there was no statistically significant intergroup difference (P = .14). CONCLUSION Magnetization transfer imaging could be useful for categorizing bone tumors as cysts, cartilaginous tumors, or noncartilaginous solid tumors.