Biomedical subjects
Publications and source records attributed to A Bonakdarpour.
Elastofibromas are benign lesions of the chest wall. We describe the first reported case of elastofibroma in the neck. Imaging features as well as location of the lesion were atypical. On computed tomography and magnetic resonance imaging the lesion contained a marked preponderance of fat, because the lesion arose within fat.
We report the radiographic findings in three cases of hyperphosphatasemia. Often classified as a congenital bone dysplasia, the skeletal manifestations of this disorder are diagnostic. These features simulate Paget's disease both radiographically and with respect to salient biochemical markers. Typically, presentation is at early childhood with skull deformity, refusal to weight bear, and bowing of the extremities. Notable radiographic features include bowing of the long bones, thickening of the cortex, osteopenia, coarsened trabecular pattern, expansion of the medullary cavity, and thickening of the intramembranous portion of the calvarium. Histologic features include absence of lamellar bone and haversian systems, with thick osteoid seams and increased number of osteoclasts. An autosomal recessive pattern of inheritance has been suggested, although autosomal dominant varieties have been postulated.
Merkel cell carcinoma (MCC) is a rare malignant tumor of the skin and often is diagnosed histologically as lymphoma, melanoma and even metastatic small cell carcinoma of the lung (SCCL). Classified as a neuroendocrine tumor, clinically it originates in the head and neck region and may present with metastatic disease at the time of presentation [1]. Osseous involvement in the past has been described to involve regional facial bones only. We present the first reported MRI findings of distant osseous metastasis from a Merkel cell carcinoma to the lumbosacral spine with associated soft tissue and epidural involvement. Appropriate treatment and patient survival depend on prompt diagnostic imaging for establishment of metastatic disease. Previous reports have advocated CT for diagnosis and staging of distant metastases [2,3]. When spinal involvement is suspected, MRI may be a more suitable modality for assessment of the epidural space and appropriate staging and follow-up in such cases.
We present the first reported MR imaging findings of a histologically proven clear cell hidradenoma. A fluid level was noted on all pulse sequences in this lesion, which demonstrated a prominent hemorrhagic component on sectioning. The presence of an enhancing nodule was also noted, differentiating this lesion from a post-traumatic hematoma. Fluid levels in a well-defined subcutaneous soft tissue mass should suggest the possibility of a hidradenoma.
RATIONALE AND OBJECTIVES: The purpose of this study was to prospectively evaluate a proton-density-weighted, three-dimensional (3D) volume fast spin-echo (SE) pulse sequence in the assessment of the lumbar spine for suspected spondylosis. MATERIALS AND METHODS: Twenty-eight patients referred for low back or lower extremity pain were imaged with both a two-dimensional (2D) protocol and a proton-density-weighted 3D volume fast SE imaging. The spinal canal, conus medullaris, intervertebral disks, neural foramina, bone marrow, and spinal alignment shown with the 3D volume fast SE pulse sequence were independently assessed by two neuroradiologists. These findings were compared with those of the routine 2D studies. RESULTS: Interpretation of disk protrusions and stenoses of the neural foramina were concordant between both protocols. No instance of cord abnormality was detected with either protocol. CONCLUSION: A 3D volume fast SE proton-density-weighted pulse sequence may provide information comparable to that of routine 2D imaging. Advantages of volume imaging include thinner sections, the capability of reconstruction into any plane, and the potential to decrease imaging time.
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RATIONALE AND OBJECTIVES: The authors prospectively evaluated a T2-weighted, three-dimensional (3D) volume, fast spin-echo (SE) pulse sequence in assessment of the cervical spine and compared it with standard imaging protocol. MATERIALS AND METHODS: Eighteen patients with neck pain underwent magnetic resonance (MR) imaging at 1.5 T with two-dimensional (2D) fast SE and axial 3D gradient-echo (GRE) protocols and with an additional sagittal T2-weighted volume fast SE protocol. The spinal cord and canal, neural foramina, and intervertebral disks were assessed by two neuroradiologists, and the results were compared with reports from the standard protocol. The quality of the partition (direct sagittal) and reconstructed images were evaluated. RESULTS: No differences existed in the assessment of spinal cord disease or disk herniation with 2D fast SE and volume fast SE imaging. Some mild variation occurred in assessment of the neural foramina. Partition images demonstrated a high level of resolution and contrast, while reconstructed images had consistently lower quality. However, this did not impede detection and grading of disk or spinal abnormalities, which were adequately shown on volume fast SE sagittal images. Neural foramina were well demonstrated on axial reconstructions from volume fast SE imaging. CONCLUSION: Volume fast SE imaging provides information about the spinal cord, canal, disks, and neural foramina that is comparable to the information provided by routine imaging. Its thinner sections and multiplanar reconstruction capability are advantages over 2D imaging. Its greater tissue contrast with better visualization of the cervical cord, greater signal-to-noise ratio, and less susceptibility artifact are advantages over 3D GRE imaging.
The purpose of this study was to determine the different patterns of anterior cruciate ligament (ACL) tears on MRI and the prevalence and accuracy of these patterns. Images were obtained on high-tesla and low-tesla units and the results compared to determine whether field strength affects the interpretation using the grading system. In 172 patients who underwent knee MRI (109 knees with high-tesla units and 63 knees with low-tesla units) and arthroscopy, there was a total of 91 arthroscopically proven ACL tears. Five patterns of ACL tears were observed and designated as type 1 (diffuse increase in signal on T2-weighted images and enlargement of the ligament, 48%); type 2 (horizontally oriented ACL, 21%); type 3 (nonvisualization of the ACL, 18%); type 4 (discontinuity of the ACL, 11%); and type 5 (vertically oriented ACL, 2%). The positive predictive value (PPV) for type 2, 4, and 5 patterns was 100% for both field strengths: for type 3 PPV was just above 80% for both field strengths. The PPV value for type 1 was 90% for the high-tesla unit and 79% for the low-tesla, unit, which was not statistically significant. Combining the results of both field strengths, the overall sensitivity and specificity were 93% and 89%, respectively. Arthroscopic results were also used to determine the association between meniscal and ACL tears. Only 13% of ACL tears were isolated, the rest being associated with meniscal tears. Forty-five percent of medial meniscal and 50% of lateral meniscal tears were associated with an ACL tear, and 94% of ACLs were torn when both menisci were torn.
Ankle ligament sprains are the most frequent sports injury, and radiographic evaluation of the ankle accounts for 10% or all radiographic examinations requested from an emergency department. This article reviews the diagnosis of the ankle sprain and the anatomy and injuries of the ankle ligaments.
Findings from magnetic resonance (MR) imaging examinations of 194 knees were interpreted retrospectively with a new classification, including not only signal intensity but morphologic abnormalities. All findings were correlated with prospectively recorded results from arthroscopic examinations performed by a knee subspecialist. Meniscal MR imaging findings were expanded to eight types in this study. Positive predictive values for each type of finding and overall accuracy were calculated. Several potential sources of error that could be differentiated through pathologic change were recognized. Sensitivity and specificity of MR imaging findings were, respectively, 95% and 74% for the medial meniscus and 86% and 90% for the lateral meniscus. As the classification grade increased, the likelihood of meniscal tear also increased. Medial meniscal tears tended to occur in a predictable pattern, extending from the posterior to the anterior horn. Thus, when a definite tear of the body or anterior horn of the medial meniscus is present, a tear of the posterior horn should be suspected, even if the findings are not convincing. This expanded classification may be useful for radiologists in expressing their level of confidence in a particular MR imaging finding suggestive of meniscal injury.
To determine the optimum foot position and imaging plane at magnetic resonance (MR) imaging of each ankle ligament, 10 cadaver ankles were dissected to visualize the orientation, precise attachment sites, and relationships of each ligament. Then eight cadaver ankles were studied with MR imaging and were cryosectioned in the optimum imaging planes. The ankles of 12 healthy volunteers were imaged to ensure consistency in identifying the normal ligaments. With the foot taped into full dorsiflexion of 10 degrees-20 degrees, axial imaging provided optimum views of the anterior, posterior, and inferior tibiofibular ligaments and of the anterior and posterior fibulotalar ligaments and provided an overview of the deltoid ligament. Coronal images provided full-length views of the tibiospring, tibiocalcaneal, and posterior tibiotalar parts of the deltoid ligament. With the foot taped into full plantar flexion of 40 degrees-50 degrees, axial imaging optimized visualization of the fibulocalcaneal ligament and of the tibionavicular and anterior tibiotalar parts of the deltoid ligament. Sagittal images provided the best full-length views of the spring ligament.
Thirteen patients with clinically diagnosed sprained ankles underwent magnetic resonance (MR) imaging. Five of these cases are presented to illustrate the potential of MR imaging to enable identification of both primary and associated ligament injury sites, grading of the severity of the injuries, and visualization of the associated findings of tendon sheath and joint effusion. The appropriate combination of foot position and imaging plane is essential to achieve full-length visualization of each ligament. Two patients demonstrated findings compatible with total gross disruption of the anterior fibulotalar ligament; two, with injury to the fibulocalcaneal ligament with effusion of the overlying peroneus tendon sheath; and one, with thinning, lengthening, and fibrotic changes involving the anterior fibulotalar ligament. MR imaging can provide a noninvasive means to evaluate the site and severity of ankle ligament injuries (a) in acute ankle injuries that demonstrate significant instability, (b) in stable acute injuries involving athletes or litigation, or (c) in patients with repeated injuries or instability in whom surgery is contemplated.
Lytic bone lesions secondary to amyloid deposition are a recently described complication of long-term hemodialysis. The authors refer to these tumorlike deposits as amyloidomas in a review of the subject and four proved cases. This entity typically appears as multiple well-defined, juxta-articular lytic lesions without matrix calcification. The duration of hemodialysis is probably the greatest risk factor for development of these intraosseous amyloidomas. Ultrastructurally, this new type of amyloid originates from beta 2-microglobulin, a low-molecular-weight serum protein that is not filtered by standard dialysis membranes.
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In Part 1 of this study, the forces and torques exerted on metallic spine implants by a 0.3-T magnetic field were evaluated using a cantilever system sensitive to forces as low as 250 mg and torques as low as 4 g/cm. Results indicated that the 0.3-T magnification field did not cause forces or torques that could be measured within this range. It is concluded that patients with spine implants may safely undergo magnetic resonance scanning. In Part 2, the magnetic resonance scans from 33 patients (61 studies) then were reviewed to determine which, if any, parameters could be adjusted to minimize artifact. Magnetic power, slice thickness, plane of scan, and pulse sequence were considered. Plane of scan was found to be the most significant parameter in achieving useful studies, with the sagittal plane being the preferred orientation. Scans of patients who had posterior wiring were more likely to be useful, while scans of patients with spinal rods usually showed a large amount of artifact.
The magnetic resonance (MR) images of 14 wrists of patients with carpal tunnel syndrome (CTS) were studied. Four general findings visible regardless of the cause of CTS included swelling of the median nerve, best evaluated at the level of the pisiform bone; flattening of the median nerve, most reliably judged at the hamate level; palmar bowing of the flexor retinaculum, best visualized at the level of the hamate bone; and increased signal intensity of the median nerve on T2-weighted images. Findings related to cause were tendon sheath edema in traumatic tenosynovitis, synovial hypertrophy in rheumatoid tenosynovitis, a ganglion cyst, and excessive amount of fat within the carpal tunnel, a persistent median artery, and a large adductor pollicis muscle. Knowledge of these findings may permit more rational choice of treatment. In four cases in which symptoms persisted after surgery, findings valuable in explaining or predicting the failure included incomplete incision of the flexor retinaculum, excessive fat within the carpal tunnel, persistent neuritis of the median nerve, and development of neuromas.
To correlate the important structures of the carpal tunnel demonstrated on magnetic resonance (MR) images with gross anatomy, the authors imaged the wrists of 20 normal volunteers and nine cadavers. The cadaver specimens were sectioned in the same planes in which they were imaged, and three other specimens were dissected. The anatomy was directly correlated with the imaged morphology. Axial images delineated well the bone and ligament walls of the carpal tunnel. The median nerve was well delimited and of moderate signal intensity. It was surrounded in some cases by fat but was consistently bound by specific tendons. The ulnar nerve and artery were visualized as they traversed the Guyon canal to their division into superficial and deep branches. Coronal images permitted optimal visualization of the triangular fibrocartilage and the radial and ulnar collateral ligaments. Quantitative studies indicated that the normal median nerve does not significantly increase in size within the carpal tunnel but does become more flattened at the level of the pisiform bone. The normal flexor retinaculum may have a slight palmar bowing.
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