Cost-effectiveness of immediate MR imaging versus traditional follow-up for revealing radiographically occult scaphoid fractures.

OBJECTIVE: For suspected scaphoid fractures with no radiographic evidence of fracture, treating symptoms with immobilization and radiographic follow-up has long been the standard of care. Modified MR imaging of the wrist is offered at our institution in screening for radiographically occult scaphoid fractures at the time of initial presentation to the emergency department. We show the advantages and comparative costs of this modified protocol versus a traditional protocol. MATERIALS AND METHODS: Our modified protocol consists of coronal thin-section T1-weighted and fast spin-echo T2-weighted MR images with fat saturation. A review of the literature was performed to assess the accuracy of clinical examination, radiography, and other modalities in the evaluation of scaphoid fractures of the wrist. Charges for this procedure are compared with charges for traditional follow-up. RESULTS: Three of four patients with positive results at clinical examination and negative findings on initial radiographs will be needlessly immobilized and monitored. The charges to the patient at our institution for screening MR imaging of the wrist are $770. The total charges to the patient with the traditional protocol, which would not be necessary with screening MR imaging, are $677 or more if a diagnosis is not made at this time. Bone scanning or routine MR imaging is often eventually used. CONCLUSION: Cost analysis at our institution suggests the two protocols are nearly equivalent from a financial standpoint. The loss of productivity for patients who are unnecessarily in casts or splints may be substantial. Screening MR imaging of the wrist in this setting is becoming accepted at our institution in a manner similar to screening MR imaging of the hip.

MR imaging of meniscal contusion in the knee.

OBJECTIVE: We describe focal abnormal signal of the meniscus in the knees of six patients who had a history of acute trauma to the knee. This signal abuts the articular surface of the meniscus on MR imaging but does not meet criteria for a meniscal tear or degeneration. CONCLUSION: Acute trauma to the knee may cause an abnormal signal in the meniscus that does not meet the previously described criteria for a meniscal tear or an intrasubstance degeneration. This abnormal signal could be misinterpreted as a tear because of its contact with the articular surface; this signal is seen most often in our series in the setting of an anterior cruciate ligament tear with adjacent bone contusions. We suggest that this signal may be due to a contusion of the meniscus and that the signal may resolve over time in some patients.

The relationship of age, gender, and degenerative changes observed on radiographs of the shoulder in asymptomatic individuals.

Radiographs of the shoulders of 84 asymptomatic individuals aged between 40 and 83 years were evaluated to determine changes in 23 specific areas. Two fellowship-trained orthopaedic radiologists graded each area on a scale of 0 to II (normal 0, mild changes I, advanced changes II). Logistic regression analysis indicated age to be a significant predictor of change (p < 0.05) for sclerosis of the medial acromion and lateral clavicle, the presence of subchondral cysts in the acromion, formation of osteophytes at the inferior acromion and clavicle, and narrowing and degeneration of the acromioclavicular joint. Gender was not a significant predictor (p > 0.05) for radiological changes. Student's t-test determined significance (p < 0.05) between age and the presence of medial acromial and lateral clavicular sclerosis, subchondral acromial cysts, inferior acromial and clavicular osteophytes, and degeneration of the acromioclavicular joint. Radiological analysis in conditions such as subacromial impingement, pathology of the rotator cuff, and acromioclavicular degeneration should be interpreted in the context of the symptoms and normal age-related changes.

The "mini brain": plasmacytoma in a vertebral body on MR imaging.

OBJECTIVE: Patients with solitary plasmacytoma in the spine frequently require a biopsy for diagnosis of their condition. We report an appearance of plasmacytoma in the spine, which is sufficiently pathognomonic to obviate biopsy. CONCLUSION: Identification of a "mini brain" in an expansile lesion in the spine is characteristic of plasmacytoma. It is important that radiologists note this characteristic because biopsy can be avoided in patients with this appearance. Although biopsy might still be required at many institutions, at our institution, surgeons find this appearance sufficiently pathognomonic to bypass biopsy and start treatment.

The MR imaging appearance of longitudinal split tears of the peroneus brevis tendon.

PURPOSE: Longitudinal split tears of the peroneus brevis tendon have been increasingly reported as a source of lateral ankle pain and disability. MR imaging is useful in identifying the appearance of longitudinal split tears of the peroneus brevis tendon to differentiate this entity from other causes of chronic lateral ankle pain. We observed variations in anatomy associated with these tears. MATERIALS AND METHODS: Twenty-two patients (eleven males, eleven females) were identified as having longitudinal split tears of the peroneus brevis tendon. These cases were reviewed retrospectively to evaluate for the following: shape of the peroneus brevis tendon, high signal in the peroneus brevis tendon, tendon subluxation, appearance of the superior peroneal retinaculum, presence of osseous changes in the ankle, lateral ankle ligaments, presence of a bony fibular spur, flattening of the peroneal groove of the fibula and presence of a peroneus quartus. A control group consisted of twenty ankles imaged for reasons other than lateral ankle pain. The same structures were assessed in this group. A Fisher's exact P-value was used to determine the significance of each finding in the two groups. RESULTS: Statistically significant associated findings were chevron shaped tendon (p = .0001), high signal in the peroneus brevis (p = .0017), bony changes (p = .0001), flat peroneal groove (p = .0001), abnormal lateral ligaments (p = .0004), and lateral fibular spur (p = .0006). CONCLUSIONS: MR imaging is useful in differentiating longitudinal split tears of the peroneus brevis tendon from other lateral ankle disorders. It can show the extent of the abnormality in the tendon and the associated findings of soft tissue and/or bone variations which must be addressed at the time of surgery.

Macrodystrophia lipomatosa with associated fibrolipomatous hamartoma of the median nerve.

Macrodystrophia lipomatosa (MDL) is a rare disease typically causing localized gigantism and is often associated with a fibrolipomatous hamartoma (FH) of the median or plantar nerve. A previously unreported case of MDL with associated FH of the median nerve is presented.

Sacral stress fractures in long-distance runners.

OBJECTIVE: Sacral stress fractures in athletes are rare but important to recognize because the symptoms often mimic sciatica and can lead to delay in diagnosis and treatment. The radiographic findings are characteristic and can facilitate early diagnosis and lead to appropriate treatment. CONCLUSION: The clinical presentation of runners with sacral stress fractures can mimic disk disease. However, stress fractures in athletes, especially long-distance runners, must be treated differently. The imaging characteristics appear as linear abnormal signal intensity paralleling the sacroiliac joint on MR imaging and linear sclerosis with cortical disruption on CT. Imaging with bone scintigraphy shows increased uptake that parallels the sacroiliac joint.

MR imaging after therapeutic injection of the subacromial bursa.

OBJECTIVE: As a therapeutic injection into the subacromial bursa (SAB) is commonly performed for impingement syndrome, it is important to know whether this fluid can be retained for a period of time and cause confusion with a pathologic collection of fluid. This study identifies and describes the appearance of recent subacromial injection using MR imaging, and the appearance of a potential complication. DESIGN AND PATIENTS: Fourteen asymptomatic shoulders were studied with MR imaging using fast spin echo T2-weighted imaging (1.5 T) prior to injection with 7 cm(3) of xylocaine. Four shoulders had subacromial fluid and were eliminated from the study. The remaining 10 (9 men, 1 woman; age range 27-36 years, average age 33 years) were then re-imaged immediately, and at 6, 12 and 24 h after the injection or until fluid resolved. Each set of images was reviewed for the presence of fluid in the SAB and for additional abnormalities. RESULTS: Fluid was identified in all subjects in the SAB in the immediate, 6 and 12 h post-injection images. At 24 h, fluid was not identified within the SAB in eight of 10 patients. In one patient fluid resolved in 48 h. The other continued to demonstrate fluid in the SAB and in the joint as well as abnormal signal in the infraspinatus muscle from a presumed myositis. Imaging was performed up to 10 days after the injection in this patient. CONCLUSIONS: It is known that fluid identified in the SAB without evidence of a cuff tear may be due to bursitis. However, if MR imaging is performed within 24 h of injection, the presence of the fluid may be iatrogenic. In addition, the history of recent therapeutic injection is very important as complications such as myositis can occur as a result of the injection. Knowledge of injection prior to imaging is vital for accurate interpretation of MR shoulder examinations.

MR imaging of fibrocartilaginous masses arising on the margins of spondylolysis defects.

OBJECTIVE: Spondylolysis is reported in up to 7% of the population. An uncommon process that can accompany a pars interarticularis defect is a fibrocartilaginous mass, which can cause impression on the nerve roots and thecal sac. Recognition is important so that the presence may be addressed at the time of surgery. This report describes the MR imaging appearance and clinical significance of a fibrocartilaginous mass in association with spondylolysis. MATERIALS AND METHODS: We reviewed data regarding 336 patients who had lumbar spine imaging at our institution during a 12-month period. Contiguous axial and sagittal MR imaging using T1-weighted and fast spin-echo T2-weighted sequences was used. Images were evaluated for a mass of tissue surrounding the pars defect with MR characteristics of cartilaginous and fibrous low signal intensity on T1-weighted images and low to intermediate signal intensity on T2-weighted images. The position of the fibrocartilaginous mass and its relation to the thecal sac were noted. Surgical correlation between those patients with a fibrocartilaginous mass and those without was examined. RESULTS: Twenty-nine (8.6%) of 336 patients were identified as having a pars interarticularis defect. A fibrocartilaginous mass was present in 26 (90%) of 29 patients. Six (21%) of the 29 patients had a mass effect on the thecal sac. Of the remaining 23 patients, 20 had a fibrocartilaginous mass external to the thecal sac, and three did not show any fibrocartilaginous mass. Histologic analysis in one patient confirmed the fibrous and cartilaginous nature of the lesion at the pars defect. CONCLUSION: A fibrocartilaginous mass was present in 90% of the patients with spondylolysis. Mass effect on the thecal sac that required surgery was identified in 21% of the patients with spondylolysis. Awareness of this mass and proper imaging protocols will enable the radiologist to preoperatively alert the surgeon to its presence.

MR imaging of the subcoracoid bursa.

OBJECTIVE: The subcoracoid bursa, a bursa anterior to the shoulder joint, can be identified on MR images. Awareness of the MR appearance and location of this bursa, which can connect with the subacromial-subdeltoid bursa, enables appropriate diagnosis in patients with shoulder pain. MATERIALS AND METHODS: Dictated reports involving all MR imaging of the shoulder (n = 1545) performed at our institution from June 1993 to February 1998 were reviewed from computer archives. Films were reviewed in 16 cases describing a subcoracoid bursa; in nine MR imaging correctly revealed this bursa, whereas in seven MR imaging revealed the subscapular recess, an outpouching of the glenohumeral joint often confused with the subcoracoid bursa. RESULTS: Of the 1545 shoulders examined, MR imaging revealed the subcoracoid bursa in nine (0.6%) patients. Two cases from a teaching file were also included, for a total of 11 cases. In five (45%) of the 11 cases, the subcoracoid bursa contained a small amount of fluid (<1 cm in largest diameter on sagittal images). In the remaining six cases (55%), the subcoracoid bursa contained a moderate (1-2 cm in largest diameter) or a large amount (>2 cm in largest diameter) of fluid. Of the 11 cases, six (55%) also showed connection with the subacromial-subdeltoid bursa. CONCLUSION: It is important to correctly identify the subcoracoid bursa on MR imaging because it is believed to cause isolated shoulder pain. Fluid in the subcoracoid bursa can also communicate with the subacromial-subdeltoid bursa.

Musculoskeletal manifestations of AIDS.

Musculoskeletal manifestations in the HIV- and AIDS-infected patient are not as common as in other organ systems. A variety of musculoskeletal abnormalities are discussed in this article, including infection, arthritis, and neoplasms. A brief discussion of miscellaneous conditions, such as avascular necrosis, hypertrophic osteoarthropathy, reflex sympathetic dystrophy, and bone marrows abnormalities is also included.

Pelvic stress injuries: the relationship between osteitis pubis (symphysis pubis stress injury) and sacroiliac abnormalities in athletes.

OBJECTIVE: To demonstrate with radiographic imaging the association between pubic stress injury and sacroiliac abnormalities in athletes. DESIGN AND PATIENTS: Eleven athletes (9 men and 2 women), comprising seven male long-distance runners, one male soccer player, one male and two female basketball players, were imaged with plain films for complaints of pubic symphysis pain, sciatica, groin pain, or a combination of these complaints. In addition to the plain films, four patients were imaged with CT, two patients had MR imaging, and a bone scan was performed in three patients. Anteroposterior plain films of the pelvis of 20 patients without back pain or pubic pain were evaluated for comparison as a control group (ages 18-72 years, average 49 years; 11 women and 9 men). RESULTS: All athletes showed plain film evidence of either sclerosis, erosions or offset at the pubic symphysis. Four had avulsion of cortical bone at the site of insertion of the gracilis tendon. Four patients demonstrated sacroiliac joint abnormalities on plain films consisting of sclerosis, erosions and osteophytes, and in one of these athletes, bilateral sacroiliac changes are present. Two patients with normal sacroiliac joints on plain films had a bone scan showing increased radionuclide uptake bilaterally at the sacroiliac joints. One patient with both plain film and CT evidence of sacroiliac abnormalities had an MR examination showing abnormal signal at both sacroiliac joints and at the pubic symphysis. A sacral stress fracture was found on CT in one patient with complaints of sciatica. In the control group, six patients, all over the age of 55 years, had mild sclerosis of the symphysis, but no plain film evidence of sacroiliac abnormalities. CONCLUSION: We have found a group of athletes in whom stress injuries to the pubic symphysis are associated with changes in the sacroiliac joint as demonstrated by degenerative changes or in the sacrum as manifested as a sacral stress fracture. These findings are probably due to abnormal stresses across the pelvic ring structure that lead to a second abnormality in the pelvic ring. The abnormality in the sacrum is not always well seen with conventional imaging. Recognition of the association of stress injury of the symphysis with back pain is important in that it can help avoid inappropriate studies and diagnostic confusion.

Absence or interruption of the supra-acetabular line: a subtle plain film indicator of hip pathology.

OBJECTIVE: To show that absence or interruption of the supra-acetabular line is a subtle plain film indicator of pathology in the acetabulum. DESIGN: Nineteen hips from 17 patients with known disease processes involving the acetabulum as demonstrated by subsequent magnetic resonance imaging, bone scan or plain film follow-up were evaluated with antero-posterior (AP) plain films of the pelvis. Three additional cases were diagnosed prospectively using interruption of the supra-acetabular line as the criterion for inclusion. Fifty AP plain films of the pelvis in patients without hip pain were examined prospectively to determine normal imaging criteria. RESULTS AND CONCLUSIONS: The normal supra-acetabular line measures 2-3 mm in thickness superiorly and is a thin sclerotic line in the medial aspect. In all 22 hips (with pathology) in this series, the line was interrupted or absent. Loss or interruption of the supra-acetabular line may thus be a subtle pain film indicator of a disease process involving the acetabulum. This plain film sign has not previously been reported.

Proper protocols key to CT of lumbar spine.

MRI is clearly superior to CT in imaging the lumbar spine for evaluation of the postoperative back. The one area in which CT has been shown to be superior to MRI in the lumbar spine is in diagnosing spondylolysis. Pars defects can be very difficult to appreciate with MRI, yet are easily seen with CT. Other than spondylolysis, the postoperative spine, and bone marrow imaging, CT and MRI appear to be diagnostically equivalent.

Calcification demonstrated as high signal intensity on T1-weighted MR images of the disks of the lumbar spine.

PURPOSE: To report that calcification of lumbar disks may not show the usual low signal intensity on T1-weighted magnetic resonance (MR) images. MATERIALS AND METHODS: The authors present five cases of high signal intensity on T1-weighted MR images of a lumbar disk that reflect the presence of calcium deposition. RESULTS: In four cases there was conventional radiographic confirmation and in one case there was computed tomographic confirmation of the disk calcification, which corresponded to the high signal intensity seen on the MR studies. One patient had undergone surgical removal of a partially calcified protruding disk. CONCLUSION: Lumbar disk calcification can vary in signal intensity from low to high on T1-weighted MR images.

Rapid triple-compartment wrist arthrography with diluted contrast medium.

Triple-compartment wrist arthrography is currently considered the optimal technique for evaluating carpal instability, because injection of contrast agent into the radiocarpal joint alone can fail to reveal ligamentous disruption due to a ball-valve tear. Unfortunately, triple-compartment arthrography can be time consuming for both the patient and the radiologist. This report describes a technique for rapid triple-compartment wrist arthrography with standard (as opposed to digital subtraction) fluoroscopy. This technique reduces the time necessary to perform the study to 30 to 45 minutes without sacrificing diagnostic accuracy.