MRI-induced retrocalcaneal bursitis

This case report describes a patient with acute retrocalcaneal bursitis, which developed after MRI examination of the ankle. The sagittal T2*-weighted gradient echo sequence revealed an extensive susceptibility artifact in the area surrounding the Achilles tendon near its insertion at the os calcis. This artifact was caused by postsurgical metallic particles. We postulate that these particles were mechanically stimulated by the magnetic field and induced the inflammatory response. Received: 20 July 1998 Revision requested: 14 September 1998, 16 March 1999 Revision received: 15 February 1999, 20 May 1999 Accepted: 21 May 1999     

Tuberculous infection of the gracilis muscle and tendon clinically mimicking deep venous thrombosis: sonographic findings

Musculoskeletal tuberculosis usually involves the spine. Tuberculous infection of muscles and tendons is rare. A patient with tuberculous infection of the gracilis muscle and tendon is reported. Lower extremity Doppler ultrasound was initially performed, as the physical examination mimicked deep vein thrombosis. Sonography identified the abnormal muscle and tendon and was then used to guide aspiration. The sonographic appearance of the gracilis muscle and tendon is described and compared with correlative MR images. Received: 21 December 1998 Revision requested: 31 January 1999 Revision received: 30 March 1999 Accepted: 31 March 1999     

Variations in meniscofemoral ligaments at anatomical study and MR imaging

Purpose To demonstrate variations in the meniscofemoral ligaments (ligaments of Wrisberg and Humphrey) at anatomical study and magnetic resonance (MR) imaging. Design Twenty-eight cadaveric knees were partially dissected for the examination of the meniscofemoral ligaments. One hundred knee MR examinations were reviewed by two experienced musculoskeletal radiologists. Proximal variations in the meniscofemoral ligaments at MR imaging were classified into three types according to the attachment site: type I, medial femoral condyle; type II, proximal half of the posterior cruciate ligament (PCL); type III, distal half of the PCL. Distal variations were classified into vertical or oblique types according to the orientation of the intermediate signal at the interface of the ligament and lateral meniscus. Results At anatomical study, six cases showed variations in the proximal insertion site of the meniscofemoral ligaments. At MR imaging 93 cases had one or more meniscofemoral ligaments, giving a total of 107 ligaments: 90 ligaments of Wrisberg and 17 ligaments of Humphrey. Forty-one ligaments of Wrisberg were type I, 28 type II, 19 type III, and with two indeterminate type, while 6 ligaments of Humphrey were type I and the remaining 11 were indeterminate. Seven cases showed no meniscofemoral ligament. Of the 107 meniscofemoral ligaments, the distal insertion orientation was of vertical type in 10 ligaments, oblique type in 70 and unidentified in 27. Conclusion An understanding of the high incidence of meniscofemoral ligament variations may help in the interpretation of knee MR studies. Received: 16 February 1998 Revision requested: 16 June 1998 Revision received: 6 October 1998 Accepted: 7 December 1998     

Arthritis and hidradenitis suppurativa diagnosed in a 48-year-old man

We report the case of a 48-year-old man who presented with an erosive, seronegative, HLA-B27-negative, peripheral polyarthritis, associated with hidradenitis suppurativa of axillae and buttocks. The pertinent literature is reviewed. This paper is the second devoted to this topic in a radiological journal and the first to document erosion of the posterior aspect of the calcaneus. Received: 15 September 1998 Revision requested: 28 October 1998 Revision received: 22 February 1999 Accepted: 22 February 1999     

MR imaging of inflammatory joint diseases of the foot and ankle

Pain affecting the foot and ankle is a common complaint frequently attributable to inflammatory joint diseases. Although conventional radiography is regarded as the initial step in the diagnostic investigation, MR imaging may contribute to further evaluation of these patients due to the direct visualization of the inflammatory soft tissue formed in the disease and its effects on bone, cartilage and para-articular structures. The high spatial resolution of MR imaging combined with tissue characterization often allows initial detection of inflammatory joint abnormalities at a stage that precedes radiographic evaluation. The typical MR appearance of certain inflammatory joint disorders may be helpful in narrowing the wide differential diagnosis. Furthermore, MR imaging can be used for an exact assessment of the extent of the disorder as well as its complications. Accurate diagnostic information can guide the clinician in further diagnostic tests and implementation of proper therapeutic treatment. Received: 12 November 1998 Revision requested: 12 February, 10 June 1999 Revision received: 14 September 1999 Accepted: 20 September 1999     

Sonographic appearance of nonoperatively treated Achilles tendon ruptures

Objective. This report describes the gray-scale and color Doppler sonographic appearance of healed Achilles tendon ruptures that have been treated nonoperatively. Design and patients. Eleven patients with acute Achilles tendon ruptures were studied with sonography in the acute setting and following nonoperative management of their torn tendon. Results. On sonographic examination, healed tendons treated nonoperatively are characterized by mild residual distortion of the normal fibrillar architecture of the tendon, anterior bulging or irregularity of the healed tendon, and a hypoechoic area about the site of rupture. Less frequent observations include mildly increased color flow and calcification at the rupture site. The previously described findings of acute tears, including hematomas, gaps at the rupture site, hyperemic torn tendon ends, and markedly distorted fibrillar architecture, were seen to have resolved in this series. Conclusion. The Achilles tendon tear treated nonoperatively has a different sonographic appearance from that of a normal or acutely ruptured tendon. Received: 24 November 1999 Revision requested: 23 January 2000 Revision received: 8 February 2000 Accepted: 8 February 2000     

Glenohumeral instability: evaluation using MR arthrography of the shoulder

In the setting of glenohumeral instability or when internal derangement of the shoulder joint is suspected, MR arthrography has been demonstrated to be an accurate diagnostic imaging technique. Knowledge of the complex anatomy of the shoulder and its variations is essential in order to maximize diagnostic accuracy. Received: 24 February 1999 Revision requested: 19 April 1999 Revision received: 12 May 1999 Accepted: 13 May 1999     

Autogenous osteochondral ”plug” transfer for the treatment of focal chondral defects: postoperative MR appearance with clinical correlation

Objective: To describe the MR appearance following autogenous osteochondral ”plug” transfer for the treatment of focal chondral defects of the knee. Design and patients: Twenty-nine 1.5-T MR knee studies including dynamic gadolinium enhancement were performed on 21 patients following autogenous osteochondral ”plug” transfer. Three musculoskeletal radiologists retrospectively reviewed images to evaluate graft and donor site appearance and MR findings were correlated with clinical outcomes. Results: MR images demonstrated graft protuberance (n=12/21; range 1–2 mm), depression (n=2/21; range 1 mm), and surface incongruity: mild (n=17/21), moderate (n=2/21), marked (n=1/21). The T2 signal of graft cartilage was similar to that of adjacent cartilage in 25 of 29 examinations, and increased in four. Graft cartilage thickness relative to adjacent cartilage was <50% in six patients, 50–100% in 15. Graft enhancement in bone was absent at 2 weeks, but present at between 4 and 6 weeks following surgery. All patients had clinical follow-up examinations and knee outcome survey scores were obtained in 15 patients with follow-up greater than 3 months after surgery. All patients demonstrated the expected short-term progressive clinical improvement. Conclusion: MR images reveal a wide range of appearances following osteochondral ”plug” transfer. Minor variations in graft orientation and surface congruity do not result in adverse clinical outcome in the short term. Received: 8 January 2001 Revision requested: 21 February 2001 Revision received: 6 March 2001 Accepted: 6 March 2001     

The influence of flip angle on the magic angle effect

Objective. To assess the impact of flip angle with gradient sequences on the ”magic angle effect”. We characterized the magic angle effect in various gradient echo sequences and compared the signal- to-noise ratios present on these sequences with the signal-to-noise ratios of spin echo sequences. Design. Ten normal healthy volunteers were positioned such that the flexor hallucis longus tendon remained at approximately at 55° to the main magnetic field (the magic angle). The tendon was imaged by a conventional spin echo T1- and T2-weighted techniques and by a series of gradient techniques. Gradient sequences were altered by both TE and flip angle. Signal-to-noise measurements were obtained at segments of the flexor hallucis longus tendon demonstrating the magic angle effect to quantify the artifact. Signal-to-noise measurements were compared and statistical analysis performed. Similar measurements were taken of the anterior tibialis tendon as an internal control. Results and conclusions. We demonstrated the magic angle effect on all the gradient sequences. The intensity of the artifact was affected by both the TE and flip angle. Low TE values and a high flip angle demonstrated the greatest magic angle effect. At TE values less than 30 ms, a high flip angle will markedly increase the magic angle effect. Received: 6 December 1999 Revision requested: 31 March 2000 Revision received: 22 May 2000 Accepted: 23 May 2000     

Synovial desmoplastic fibroblastoma of hip joint with bone erosion

A 78-year-old woman presented with pain at the left hip. Initial radiographs showed minimal age-related changes. Over the next 2 years she developed large erosions in the left femoral neck and proceeded to hip replacement. Histological examination showed bland spindle cells in a loose and hyalinised collagenous stroma considered to represent a desmoplastic fibroblastoma (collagenous fibroma). This is the first reported case of synovial desmoplastic fibroblastoma. Received: 23 November 1998 Revision requested: 16 December 1998 Revision received: 10 February 1999 Accepted: 4 March 1999     

Castleman disease: CT and MR imaging features of a retroperitoneal location in association with paraneoplastic pemphigus

We describe the CT and MRI features of a case of Castleman disease which was unusual by both its retroperitoneal location and its association with paraneoplastic pemphigus. Received: 9 July 1998; Revision received: 16 November 1998; Accepted: 12 January 1999     

Complete rupture of the distal semimembranosus tendon with secondary hamstring muscles atrophy: MR findings in two cases

Complete rupture of the hamstring muscles is a rare injury. The proximal musculo-tendinous junction is the most frequent site of rupture. We present two cases of complete rupture of the distal semimenbranosus tendon, which clinically presented as soft-tissue masses. MR imaging permitted the correct diagnosis. There has been only one other such case reported. Received: 15 October 1999 Revision requested: 6 February 2000 Revision received: 8 March 2000 Accepted: 13 March 2000     

Extraskeletal myxoid chondrosarcoma of the knee

Extraskeletal myxoid chondrosarcoma is an uncommon neoplasm, accounting for less than 2% of all soft tissue sarcomas. It affects adult males with a median age in the fifth decade at the time of diagnosis. The tumor usually arises in the deep soft tissues, especially in the lower extremities. Patients present with a gradually enlarging mass that may or may not be associated with pain. This report describes a 25-year-old man who initially presented with a 4- to 5-year history of right knee pain and an enlarging mass in the right knee. Evaluation revealed a cartilaginous neoplasm with no evidence of metastatic disease. The tumor was widely excised and an allograft reconstruction was performed. The patient was closely followed with an eventual above the knee amputation for recurrent myxoid chondrosarcoma. At 34 months, retroperitoneal metastases were noted on abdominal CT. The patient underwent a left radical nephrectomy, renal vein thrombectomy and enucleation of the mass in the right kidney, distal pancreatectomy, and splenectomy. The patient received postoperative chemotherapy. Forty-eight months after initial diagnosis, the patient was found to have recurrent abdominal and retroperitoneal lesions. At 64 months, the patient died from complications of extraskeletal myxoid chondrosarcoma. Received: 6 July 1998 Revision requested: 7 August 1998 Revision received: 29 January 1999 Accepted: 3 February 1999     

MR imaging of non-squamous vaginal tumors

We reviewed the MR images and pathologic findings of five cases of primary vaginal neoplasms of non-squamous origin. Histologic types consisted one case each of adenocarcinoma, adenosarcoma, melanoma, lymphoma, and neurilemoma. Magnetic resonance imaging was found useful for evaluating the type and the extension of vaginal tumors. Received: 8 April 1998; Revision received: 6 November 1998; Accepted: 27 January 1999     

Primary leiomyoma of the ovary: a case report

The imaging features of primary ovarian leiomyoma have seldom been described because of the very low prevalence of the tumor. Herein we present a case report on its magnetic resonance imaging features. Both T1- and T2-weighted images revealed a low-signal-intensity mass, which was well circumscribed and sharply demarcated from the uterus. Magnetic resonance imaging was useful in distinguishing it from a malignant ovarian tumor and uterine leiomyoma. Received 10 October 1997; Revision received 2 February 1998; Accepted 4 February 1998     

Fibrolipomatous hamartoma: pathognomonic on MR imaging

Purpose. To assess the MR imaging characteristics, presenting symptoms, age and nerve distribution of fibrolipomatous hamartoma. Design. A computer search was performed of the term fibrolipomatous hamartoma through the musculoskeletal section MR imaging results at our institution from June 7, 1996 to January 21, 1998 followed by a search of the terms lipomatous hamartoma, median nerve, surrounding fat, increased fatty signal, coaxial, and neuroma. MR images and medical files were retrospectively reviewed by two experienced musculoskeletal radiologists for imaging characteristics, nerve and age distribution as well as for history of trauma. In addition three consultation cases from outside institutions were added for determination of image characteristics. Results. Ten fibrolipomatous hamartomas were identified: eight in the median nerve, one in the ulnar nerve and one in the sciatic nerve. Mean age was 32.3 years (range 4–75 years, SD 21 years). Imaging characteristics were serpiginous low-intensity structures representing thickened nerve fascicles, surrounded by evenly distributed fat, high signal intensity on T1-weighted sequences and low signal intensity on T2-weighted sequences. The amount of fat varied; however, distribution in eight cases (80%) was predominantly between nerve fibers rather than surrounding them peripherally. All had a coaxial-cable-like appearance on axial planes and a spaghetti-like appearance on coronal planes that was not seen in any other type of median nerve abnormality imaged during the study period. Conclusion. The MR imaging characteristics of fibrolipomatous hamartoma are pathognomonic, obviating the need for biopsy for diagnosis. Received: 19 October 1998 Revision requested: 11 December 1998 Revision received: 22 January 1999 Accepted: 25 January 1999     

Parosteal lipoma with hyperostosis

A case of parosteal lipoma of the femur combined with hyperostosis is presented. The parosteal lipoma is a rare benign tumor containing adipose tissue and is intimately related to the periosteum. We report the MRI features and correlative pathologic findings of a parosteal lipoma. The MRI technique is useful for evaluating the relationship between the periosteum and the lipoma. Received: 5 November 1998; Revision received: 11 January 1999; Accepted: 10 February 1999     

Pectoralis major muscle and tendon tears: diagnosis and grading using magnetic resonance imaging

 Objective. To assess the accuracy and utility of magnetic resonance (MR) imaging in the detection and grading of pectoralis major muscle and tendon tears. Design and patients. A retrospective review was carried out of 10 patients referred for MR imaging for suspected pectoralis muscle injury and possible operative therapy. The pectoralis muscle and tendon were imaged using thin (3–4 mm) axial sections with a variety of sequences combined for anatomical delineation (T1-weighted SE or PD SE) and fluid detection (T2-weighted SE, T2-weighted FSE with fat suppression, or STIR). Surgical correlation was available in six patients. Clinical follow-up was available in four patients treated by nonoperative therapy. Results. MR imaging identified five complete tears, four partial tears and one normal tendon. One complete and one partial tear were at the myotendinous junction. The remaining seven injuries were at the enthesis. Surgical correlation consisted of five complete tears and one partial tear. One complete and one partial tear were at the myotendinous junction with the remaining four complete tears at the enthesis. The MR interpretation and surgical findings were in agreement in all six cases. All four patients treated with nonoperative therapy demonstrated improvement at a clinical follow-up examination, with restoration of function and strength consistent with a healed prior partial injury. Conclusion. MR imaging is accurate and useful in detecting and grading tears involving the pectoralis major muscle and tendon, facilitating the identification of patients with complete tears who are candidates for operative therapy. Received: 7 June 1999 Revision requested: 22 June 1999 Revision received: 16 February 2000 Accepted: 21 February 2000     

Atypical MRI presentation of a small splenic hamartoma

Hamartomas of the spleen usually appear isointense on T1-weighted MR images and hyperintense on T2-weighted images. We describe a histologically proven case which presented as a small (2.5 cm) focal mass isointense to splenic parenchyma on T1-weighted images and hypointense on both turbo-spin-echo T2 and short T1 inversion recovery images. Dynamic MRI revealed a delayed enhancement during the arterial phase becoming isointense and prolonged on subsequent images. This prolonged enhancement has previously been described as a characteristic pattern in these tumours. The lack of oedema and necrosis and the presence of fibrous tissue in the hamartoma at histopathology likely account for the low signal intensity on all sequences. Received: 9 February 1998; Revision received: 13 July 1998; Accepted: 17 July 1998     

Soft tissue Burkitt's lymphoma: radiological findings

An unusual case is reported of a soft tissue mass in the lower extremity, without bone involvement, in an 85-year-old woman; the histopathological diagnosis was Burkitt's lymphoma. Pertinent clinical history, histological examination, and imaging procedures allowed early diagnosis. To our knowledge, the radiological findings in Burkitt's lymphoma with this unusual clinical presentation have not been described previously. Received 27 October 1997; Revision received 6 February 1998; Accepted 18 February 1998