Margaret A. Stull

Magnetic resonance appearance of peripheral nerve sheath tumors

Magnetic resonance imaging (MRI) was used to evaluate 22 histologically proven peripheral nerve sheath tumors, approximately two-thirds of which arose in the lower extremity. The histologic distribution was as follows: 12 schwannomas, 7 neurofibromas, and 3 malignant peripheral nerve sheath tumors (2 of which occurred in patients with neurofibromatosis). Most lesions demonstrated an intermediate to moderately bright signal on T1-weighted images and were minimally inhomogeneous. All lesions were moderately bright on proton-density-weighted images and bright on T2-weighted images, again with variable inhomogeneity. The extent of the tumor was best assessed on proton-density- and T2-weighted images. Smooth margins were noted in 19 lesions. Of the 3 remaining lesions, 2 were malignant (but had been subjected to biopsy prior to MRI), and the other lesion was a plexiform neurofibroma. MRI accurately determined the relationship between the lesion and the adjacent neurovascular structures and muscles, thereby assisting surgical management. On MRI, 5 lesions demonstrated coexistent subtle muscle atrophy along the longitudinal axis of surrounding or distally innervated musculature. This latter finding, together with the presence of a tumor in the vicinity of a large nerve trunk, suggests a peripheral nerve sheath neoplasm.

Clinically Missed Cancer: How Effectively Can Radiologists Use Computer-Aided Detection?

OBJECTIVE The purpose of this study was to determine the effectiveness with which radiologists can use computer-aided detection (CADe) to detect cancer missed at screening. MATERIALS AND METHODS An observer study was performed to measure the ability of radiologists to detect breast cancer on mammograms with and without CADe. The images in the study were from 300 analog mammographic examinations. In 234 cases the mammograms were read clinically as normal and free of cancer for at least 2 subsequent years. In the other 66 cases, cancers were missed clinically. In 256 cases, current and previous mammograms were available. Eight radiologists read the dataset and recorded a BI-RADS assessment, the location of the lesion, and their level of confidence that the patient should be recalled for diagnostic workup for each suspicious lesion. Jackknife alternative free-response receiver operating characteristic analysis was used. RESULTS The jackknife alternative free-response receiver operating characteristic figure of merit was 0.641 without aid and 0.659 with aid (p = 0.06; 95% CI, -0.001 to 0.036). The sensitivity increased 9.9% (95% CI, 3.4-19%) and the callback rate 12.1% (95% CI, 7.3-20%) with CADe. Both increases were statistically significant (p < 0.001). Radiologists on average ignored 71% of correct computer prompts. CONCLUSION Use of CADe can increase radiologist sensitivity 10% with a comparable increase in recall rate. There is potential for CADe to have a bigger clinical impact because radiologists failed to recognize a correct computer prompt in 71% of missed cancer cases [corrected].

Isolated popliteal vein entrapment

We present two cases of isolated popliteal vein entrapment caused by the lateral head of the gastrocnemius muscle confirmed by both venography and magnetic resonance imaging of the knee.

Case report 496

Fig. 2. A An AP radiograph of the knees demonstrates a permeative pattern of osteolysis in the distal femoral metaphyses (arrows) and similar but less extensive abnormalities in the proximal ends of the tibiae (arrowheads). B, C Cross table lateral radiographs of the right (B) and left (C) knee show air-fluid levels in the distal ends of the femora (arrowheads). Note the relative lack of soft tissue swelling and periosteal reaction with preservation of the fat planes in the soft tissues

Paget's disease of the patella

Five patients with Pagets disease involving the patella were evaluated for the following radiographic features: trabecular pattern, cortical integrity, density, and size of the affected patella. Radiographic appearances consisted of minimal trabecular coarsening in the patella of nearly normal size and progressed to considerable cortical thickening and osteoblastic remodeling in a dramatically enlarged patella. The radiologic features of Pagets disease of the patella are distinctive and should obviate biopsy.

Open-quiz solution Case report 610

In summary, a case of amyloid arthropathy of the left ankle in a 64-year-old patient with multiple myeloma is presented. The asymmetric presentation and site of deposition in the ankle were taken to be unusual. Involvement of both hips and the right shoulder was also suspected on subsequent evaluation. The patients history and MR studies were essential in establishing the preoperative diagnosis. The extent of involvement, destruction of underlying cartilage, associated effusion and tenosynovitis were optimally defined by the MR images. The MR images also provided preoperative guidance in determining the approach and optimum site of biopsy.