Asako Yamamoto

Three cases of collagenous fibroma with rim enhancement on postcontrast T1-weighted images with fat suppression

Collagenous fibroma, also known as desmoplastic fibroblastoma, is a benign fibrous soft tissue tumor showing gradual growth, commonly without aggressive local infiltration. Today, preoperative radiological diagnosis is important to avoid over-treatment and unnecessary extensive procedures, but is difficult because diagnostic imaging findings for collagenous fibroma have not been established. We report MR imaging findings of three collagenous fibromas in correlation with their histopathology. The characteristic rim enhancement on post-contrast T1-weighted images with fat suppression was present in all three cases, and we consider this to represent the difference in vascularity between the outer capsule-like fibrous tissue and the inside of the tumor.

A case of Proteus syndrome with severe spinal canal stenosis, scoliosis, and thoracic deformity associated with tethered cord

Proteus syndrome is a rare, sporadic, hamartomatous disorder manifesting with multifocal overgrowth of tissue. The features seem to develop most often during childhood. Vertebral overgrowth with severe spinal canal stenosis is unusual, although scoliosis with abnormal vertebral bodies is one of the typical features of Proteus syndrome. We report a case of Proteus syndrome with severe spinal canal stenosis, scoliosis, cervical kyphosis, and thoracic deformity with airway obstruction because of asymmetrical overgrowth of vertebrae and ribs associated with a tethered cord, lipomas, strawberry hemangioma, flat nasal bridge, and bilateral hypoplasty of the first metatarsal bones with hyperplasty of soft tissue.

Chondromyxoid fibroma of the rib with prominent exophytic configuration

Chondromyxoid fibroma (CMF) of the rib is exceedingly unusual and few detailed image findings have been reported. Plain radiograph, computed tomography (CT), and magnetic resonance (MR) imaging findings and pathological aspects of a case of CMF of the right 2nd rib in a 15-year-old woman are reported, which was difficult to diagnose preoperatively. Though it is challenging to diagnose CMF preoperatively, it is important to be aware that CMF can exhibit atypical prominent exophytic features in unexpected locations such as the ribs.

Synovial hemangioma of the hip joint with pathological femoral neck fracture and extra-articular extension.

Synovial hemangioma is a rare benign intra-articular vascular tumor that mostly occurs in the knee joint (97%); only one case of synovial hemangioma in the hip joint has been reported [1–7]. The common symptoms of synovial hemangioma are persistent pain, limitation of motion, painful joint swelling, nontraumatic recurrent hemarthrosis, and progressive joint destruction due to nontraumatic recurrent hemarthrosis on occasion. Although aggressive intraand extra-articular extensions invading adjacent bone and soft tissue structures have been reported in some cases of synovial hemangioma in the knee joint, no cases of severe bone destruction resulting in pathological fracture have been reported [1–5, 8, 9]. The clinical features of synovial hemangioma in the hip joint are not well understood because it is very rare and presents different anatomical characteristics from synovial hemangioma in the knee [7]. Herein, we report a case of invasive synovial hemangioma of the hip with pathological femoral neck fracture and extra-articular extension, and discuss the clinical features of this condition.

Precision and accuracy in CT attenuation measurement of vascular wall using region-of-interest supported by differentiation curve

OBJECTIVES To evaluate the precision and accuracy in CT attenuation measurement of vascular wall using region-of-interest (ROI) supported by differentiation curves. STUDY DESIGN We used vascular models (actual attenuation value of the wall: 87HU) with wall thicknesses of 1.5, 1.0, or 0.5mm, filled with contrast material of 250, 348, or 436HU. The nine vascular models were scanned with a 64-detector CT. The wall attenuation values were measured using three sizes (diameter: 0.5, 1.0, and 1.5mm) of ROIs without differentiation curves. Sixteen measurements were repeated for each vascular model by each of two operators. Measurements supported by differentiation curves were also performed. We used analyses of variance with repeated measures for the measured attenuations for each size of the ROI. RESULTS Without differentiation curves, there were significant differences in the attenuation values of the wall among the three densities of contrast material, and the attenuation values tended to be overestimated more as the contrast material density increased. Operator dependencies were also found in measurements for 0.5- and 1.5-mm thickness models. With differentiation curves, measurements were not possible for 0.5- and 1.0-mm thickness models. Using differentiation curves for 1.5-mm thickness models with a ROI of 1.0- or 1.5-mm diameter, the wall attenuations were not affected by the contrast material densities and were operator independent, measuring between 75 and 103HU. CONCLUSIONS The use of differentiation curves can improve the precision and accuracy in wall attenuation measurement using a ROI technique, while measurements for walls of ≤1.0mm thickness are difficult.

Magnetic resonance imaging findings compared with histological findings of the labrum in hip osteoarthritis

Patients with disorders such as acetabular dysplasia or femoroacetabular impingement are at risk of developing hip osteoarthritis. Assessment of the cartilage and labrum in the hip joint based on magnetic resonance imaging (MRI) has been challenging because of the low signal-to-noise ratio (SNR) due to its deep location, ball and socket structure, and small volume of those structures compared with the whole joint size. To achieve better imaging assessment, direct MR arthrography (d-MRA) [1] and other techniques such as T2* mapping [2], T2 mapping [3], T1rho [4], and delayed gadolinium-enhanced MRI (dGEMRIC) [5] have been developed along with the increasing use of high-field MRI. In patients with no apparent osteoarthritic changes such as joint space narrowing or osteophyte and subchondral cyst formation on radiographs, these techniques can detect early cartilage or labral damage [6]. A recently developed semiquantitative MRI-based scoring system for hip osteoarthritis [7] includes evaluation of the labrum, and its application as a potential therapeutic monitoring tool is anticipated. The labrum shows pathological changes such as macroscopic hypertrophy and histological degeneration in hip osteoarthritis, but the pathological background is not well understood when evaluated byMRI. Kubo et al. [8] compared radial MRI findings with histological changes of the labrum in 11 hips with osteoarthritis using 1.5-T MRI and found that fibrous separation and mucoid deposition occurred in the labrum with a “diffuse high signal” or “obscure” pattern. However, to the best of our knowledge, no studies have demonstrated a correlation between MRI findings and histological evidence of the severity of degeneration of the labrum. We hypothesized that radially reconstructed images of the acetabular labrum acquired by 3-T MRI can depict degenerative changes of the labrum. In this study, we sought to determine the correlation betweenMRI and histological findings of the labrum in osteoarthritic hips.