Mariko Hosono

Septum-like structures in lipoma and liposarcoma: MR imaging and pathologic correlation

ObjectiveTo investigate the septum-like structures in pre-dominantly lipomatous tumors, by correlating fat-suppressed MR images with histopathologic findings.Design and patientsThe MR findings of three cases of well-differentiated liposarcoma (atypical lipoma), one case of lipoma-like component of dedifferentiated liposarcoma, and nine cases of lipoma were analyzed. T1-, T2-, and fat-suppressed T1-weighted images after Gd-DTPA administration were obtained. Surgical specimens from five patients (four with liposarcoma and one with lipoma) were also scanned with a MR unit, and compared with the pathologic findings.Results and conclusionsEnhancement features of lipoma and liposarcoma were well visualized on fat-suppressed T1-weighted images after Gd-DTPA administration. The septum-like structures of liposarcoma are thick and enhanced considerably, while septa of lipoma are thin and enhanced only slightly. Pathologically, the septum-like structures of liposarcoma contained muscle fibers and the septa of lipoma represented fibrous capsule. Identification of well-enhanced septa in a predominantly lipomatous tumor helps to differentiate malignant tumors from lipomas. As the septum-like structures of lipo-sarcoma contain a skeletal muscle component the tumor might need more extensive surgical procedures including resection of adjacent muscles.

MR appearance of parasymphyseal insufficiency fractures of the os pubis

Abstract Objective. To clarify the MRI features of parasymphyseal insufficiency fractures of the os pubis. Design and patients. MRI was performed in four postmenopausal women with parasymphyseal insufficiency fractures. The diagnosis was confirmed with plain films in every patient. T1-weighted and T2-weighted images were obtained in four patients using a 1.5-T unit. Postcontrast T1-weighted imaging was also done in three patients. Results and conclusions. MRI of pubic parasymphyseal insufficiency fracture characteristically demonstrates a hyperintense mass lesion with a hypointense rim on T2-weighted imaging, showing peripheral and septal enhancement after contrast administration. It is important to have this entity in mind in patients with osteoporosis, especially in patients with a history of pelvic irradiation for malignant disease, so as not to misinterpret it as a chondroid tumor or bone metastasis.

MRI and scintigraphic features of extraabdominal desmoid tumors

To determine whether extraabdominal desmoid can be correctly diagnosed using both magnetic resonance imaging (MRI) and scintigraphy with pentavalent technetium-99m dimercaptosuccinic acid and gallium-67 citrate, MRI (T1- and T2-weighted images) and scintigraphy were performed in 18 patients with 27 histologically proved extraabdominal desmoid tumors. The extraabdominal desmoid tumors were characterized by positive uptake of pentavalent technetium-99m dimercaptosuccinic acid and lack of uptake of gallium-67 citrate on scintigraphy. These tumors were isointense to skeletal muscle on T1-weighted MRIs and hyperintense on T2-weighted images. They also displayed septum-like internal inhomogeneity and surrounding hypointense capsular band. The combination of scintigraphy and MRI is of value in correctly diagnosing extraabdominal desmoid tumors except in the rare case of fibrotic verylow-grade sarcoma.

Involvement of Muscle by Malignant Lymphoma: Mr and Ct Appearances

Objective The purpose of this study is to investigate the CT and MR findings of muscular involvement by malignant lymphoma and identify the CT and MR features that may assist in their diagnosis. Materials and Methods Magnetic resonance imaging was performed on four patients (five lesions) with pathologically proven non-Hodgkin lymphoma using a 1.5 T unit (Cases 1, 2, and 4) and a 0.5 T scanner (Case 3), Computed tomography scans were carried out on three patients (Cases 1, 3, and 4). Results The lesions that extended along muscle fascicles with preserved fat planes looking like swelling of the muscle were of slightly hyper- to isointensity relative to uninvolved muscles on T1-weighted images, of hyperintensity on T2-weighted images, and of low or isodensity on CT. Microscopically, lymphoma cells were seen clustering among normal and atrophic muscle fibers in a biopsy specimen of one patient. The lesions enhanced relatively homogeneously after Gd-DTPA injection. In three cases, vessels were coursing through the lesion on MRI and in two cases on enhanced CT. Conclusion Magnetic resonance imaging proved useful to show the extension of involvement of muscular lymphoma compared with CT. The diagnosis of infiltration of muscle by lymphoma is entertained when a lesion of relatively homogeneous intensity and density extends along the muscle fascisles without obliteration of the fat planes and especially when vessels are identified within the lesion.

Periosteal ganglion of the tibia

Abstract Radiographic, computed tomographic and scintigraphic findings of a patient with separated, multilocular periosteal ganglion are reported. Multiple periosteal cystic masses with calcification in small parts of the cyst walls were demonstrated in the surface of the left tibia by plain radiograms and CT. The accumulations of technetium-99m hydroxymethylene diphosphonate and pentavalent technetium-99m dimercaptosuccinic acid were shown in the calcification in the periosteum and wall of the cyst. Needle puncture revealed that the masses were filled with jelly-like fluid. The masses were diagnosed as multiple ganglionic cysts at the periosteum of the left tibia.

Three-dimensional display of cardiac structures using reconstructed magnetic resonance imaging.

It is sometimes difficult to understand the three-dimensional (3D) relationship of cardiac and mediastinal structures despite advances in magnetic resonance (MR) imaging techniques. We present a low-cost system for 3D reconstruction of the major mediastinal structures by processing the MR imaging data on a NeXT workstation. MR images of multisection, multiphase, spin-echo techniques stored in a picture archiving and communication system (PACS) data base were used for the reconstruction. The computer program obtained the contours of the multiple components of the mediastinal structures by the combination of automatic and manual procedure. The bundled software of a 3D kit was used for surface rendering of hidden surface removal, shading of the visible parts of the surfaces, perspective transformation, and motion parallax by rotation of the surfaces. 3D reconstruction was performed in 15 patients with cardiac diseases, and the 3D-reconstructed images were compared with the plain chest x rays of the patients. The 3D presentation clearly showed the complex anatomy of cardiovascular diseases and helped elucidate the misconceptions in the interpretation of the plain chest x rays. Our 3D images are used for education and should be viewed by medical students and beginners in radiology at an individual pace with plain chest radiographs, MR images, and legends. Although applied to the heart and the great vessels in this report, this system is also applicable to other structures.

Solitary muscular involvement by tuberculosis: CT, MRI, and scintigraphic features

The authors reported computed tomography (CT), magnetic resonance imaging (MRI) and scintigraphic findings of a patient with solitary muscular tuberculosis in the forearm. All these findings resembled those of other granulomatous inflammatory lesions in the soft tissue such as muscular sarcoidosis.

Tumoral calcinosis-like metastatic calcification in a patient with renal osteodystrophy CT and scintigraphic appearances

Hyperparathyroidism and renal osteodystrophy are the disorders usually associated with metastatic calcifications, including tumoral-calcinosis-like calcification in soft tissue in dialysis patients. Tumoral calcinosis is a hard, juxta-articular mass comprised of septal, thick connective tissue and cavities filled with a dense milky substance. The authors report plain radiographic, CT, and scintigraphic findings of a large tumoral-calcinosis-like metastatic calcification accompanying renal osteodystrophy in a renal dialysis patient. This rare form of metastatic calcification and renal osteodystrophy as a background condition were demonstrated on bone imaging.

3D-spiral CT of multiple exostoses.

We report pre- and post-operative three-dimensional (3D)-spiral CT images in a patient with multiple exostoses. Images of 3D-CT, which were performed using the integrated 3D software of the CT system, showed the exact shapes and locations of the individual tumors around the knee joint in comparison with the surgical findings and resected specimen. 3D-spiral CT images of multiple exostoses would be useful for the planning of surgical procedure.

A case of melorheostosis with a 14-year follow-up

Melorheostosis is a benign sclerosing dysplasia with a very unusual and characteristic roentgenographic appearance. We reported a patient with melorheostosis in the left lower extremity followed up for 14 years. Although the extraosseous lesions only slightly enlarged, the bone scintigraphy showed the activity of the metabolism to be still high.