Rare case of a radiographically occult sacral lesion detected on MRI presenting with intractable back pain.

We report the imaging findings and histopathology of a rare case of sacral hibernoma in a female presenting with right buttock pain while sitting. The lesion was occult on radiographs and CT scan. A small, rounded right S2 lesion was hypointense on T 1 weighted images and hyperintense on short tau inversion-recovery images. It demonstrated homogeneous contrast enhancement. The lesion was biopsied, and histopathology revealed an intraosseous hibernoma composed of brown fat cells. Intraosseous hibernomas are rare and demonstrate non-specific imaging findings requiring biopsy for diagnosis, although most hibernomas are incidental and asymptomatic. Initial treatment with microwave ablation and cementoplasty improved the patient's symptoms temporarily but cementoplasty caused radicular symptoms, and eventually, cement removal, bone curettage, grafting and sacral nerve root decompression were required for symptom remission.

Efficacy of MRI in classifying proximal focal femoral deficiency.

OBJECTIVE: To evaluate the efficacy of MRI in classifying PFFD and to compare MRI to radiographic classification of PFFD. DESIGN: Radiographic and MRI classification of the cases was performed utilizing the Amstutz classification system. PATIENTS: Retrospective evaluation of radiographs and MRI exams in nine hips of eight patients with proximal focal femoral deficiency was performed by two radiologists. RESULTS: The cases were classified by radiographs as Amstutz 1: n=3, Amstutz 3: n=3, Amstutz 4: n=1 and Amstutz 5: n=2. The classifications based on MRI were Amstutz 1: n=6, Amstutz 2: n=1, Amstutz 3: n=0, Amstutz 4: n=2 and Amstutz 5: n=0. Three hips demonstrated complete agreement. There were six discordant hips. In two of the discordant cases, follow-up radiographs of 6 months or greater intervals were available and helped to confirm MRI findings. Errors in radiographic evaluation consisted of overestimating the degree of deficiency. CONCLUSION: MRI is more accurate than radiographic evaluation for the classification of PFFD, particularly early on, prior to the ossification of cartilaginous components in the femurs. Since radiographic evaluation tends to overestimate the degree of deficiency, MRI is a more definitive modality for evaluation of PFFD.

MR imaging features of tumors of the ankle and foot.

MR imaging is a useful technique in the work-up of neoplasms of the foot and ankle. Certain MR imaging traits may confer a specific diagnosis. For instance, the presence of fat in a homogeneous lesion would indicate a lipoma, while an intraarticular, poorly defined mass with low signal intensity on all pulse sequences is suspicious for pigmented villonodular synovitis. Most neoplasms, however, have no specific trademark MR features. In these cases, MR imaging is useful in imparting information that can assist in treatment and prognosis once a histologic diagnosis is made. For instance, MR imaging may help ascertain the presence and degree of bone marrow involvement, invasion of adjacent anatomical structures, and size of the lesion. MR imaging is an essential and effective modality for the preoperative staging of neoplasms of the foot and ankle.

Evaluation of a contraceptive device with MR imaging.

The purpose of this investigation is to evaluate the positioning and to confirm the volume concept of the Lea's Shield diaphragm utilizing MR imaging. We evaluated the device in two women, one nulliparous and one multiparous. We were able to comprehensively evaluate the device in both patients and answer all questions regarding anatomical positioning and aspects pertaining to the morphology of the device relevant to its function. MRI may be effectively utilized to evaluate contraceptive devices and their relationship to adjacent anatomical structures. This may enhance the gynecologist's clinical assessment of its correct positioning and efficacy.

Efficacy of combined technetium-99m sulfur colloid/indium-111 leukocyte scans to detect infected total hip and knee arthroplasties.

The reliability of combined indium-111 leukocyte/technetium-99m sulfur colloid scans, with and without the addition of blood pooling and blood flow studies, in the diagnosis of infected total joint arthroplasty was investigated. Both scans were performed on 58 patients before reoperation of total hip or knee arthroplasty in the period 1996-1999. Results for imaging alone included 100% specificity, 46% sensitivity, 100% positive predictive value, 84% negative predictive value, and 88% accuracy. Inclusion of blood pooling and flow phase data improved results to 66% sensitivity, 89% negative predictive value, and 90% accuracy, with reductions in specificity (98%) and positive predictive value (91%). Routine use of these radionuclide scans is not supported by these data.

Hyperphosphatasemia: report of three cases.

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.

Elastofibroma of the neck.

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.

Endorectal surface coil MR imaging as a staging technique for rectal carcinoma: a comparison study to rectal endosonography.

BACKGROUND: Preoperative staging of rectal cancer is critical for guiding therapy and prescribing the most appropriate treatment option. The purpose of this investigation was to compare the accuracy of endorectal surface coil magnetic resonance imaging (ERSCMRI) with endosonography (EUS) in staging rectal lesions. METHODS: Fourteen patients with rectal carcinoma, initially detected by barium enema or sigmoidoscopy underwent ERSCMRI and EUS. Subsequent resection of the lesions was performed, and the staging accuracies of these two modalities are compared. RESULTS: MR T-staging agreement with pathologic T-staging was similar to that of EUS, but MR enabled more accurate identification of nodal involvement. CONCLUSION: ERSCMRI produced greater overall accuracy in staging for rectal carcinoma than did EUS.

MRI appearance of cervical incompetence in a pregnant patient.

Ultrasonography is currently the principal imaging modality for diagnosing cervical incompetence during pregnancy. Various technical factors, both patient and technologist/transducer related, may limit its evaluation for cervical incompetence. MRI is not dependent on these technical considerations. MRI may demonstrate a higher degree of soft tissue contrast than ultrasonography for depicting uterine anatomy. MRI may, in some instances, be more accurate in depicting cervical incompetence in the gravid patient. We present the first case of cervical incompetence in a pregnant patient diagnosed by MRI, in which ultrasonography failed to provide conclusive evidence of extra-uterine herniation of the amniotic sac.

MRI appearance of placenta percreta and placenta accreta.

The purpose of this paper is to describe the magnetic resonance imaging (MR) features of placenta accreta and percreta. We retrospectively reviewed MRI findings in four cases of placenta accreta/percreta to determine features which assist in identifying the presence and extent of placental implantation abnormality. All patients had ultrasound (US) examinations. Pathologic correlation was available in all cases. There were two cases of placenta percreta and two cases of placenta accreta. All cases were treated by hysterectomy. In the two cases of placenta percreta, the placenta demonstrated transmural extension through the uterus (percreta) on MRI. In the two cases of placenta accreta, the location of thinning in the uterine wall correlated with the location of placental invagination into the myometrium at pathology. US correlation was available in all four cases. Gray scale US did not demonstrate placental invasion in any of the four cases of placenta accreta/percreta, however, in two of three cases in which color Doppler was performed, there was flow at the uterine margin suspicious for implantation abnormality. In conclusion, MRI is useful for identifying the presence and extent of placenta accreta/percreta.

Volume (three-dimensional) fast spin-echo imaging of the lumbar spine.

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.

Clinical significance of increased density in the proximal femoral marrow detected by visual inspection on abdominopelvic postcontrast CT examination.

PURPOSE: The purpose of this study was to ascertain the clinical significance of increased density of the proximal femoral diaphyseal marrow when incidentally detected on postcontrast abdominopelvic CT examinations. METHOD: The proximal femoral marrow of 63 patients was classified as normal or abnormal based on visual inspection by three attending radiologists. Abnormal density was defined as attenuation greater than that of adjacent musculature. The attenuation of the marrow was also measured. All patient medical records were reviewed for pertinent laboratory and clinical data. RESULTS: Increased marrow density had a low sensitivity for anemia (28%) but a high specificity and positive predictive value (100%) for anemia. Three of these patients had unilaterally increased attenuation associated with local pathology. Visual inspection was adequate for identifying abnormalities in instances of underlying malignancy. CONCLUSION: Increased density of the proximal femoral diaphysis is a highly specific finding for a marrow replacement process. Anemia was the most common clinical diagnosis in our series of patients with abnormal marrow density. Although the sensitivity for increased bone marrow attenuation is low, the extremely high specificity and positive predictive value of this finding for marrow reconversion and/or replacement suggest that even if detected incidentally, it should not be disregarded and, in the absence of a preexisting causative diagnosis, warrants further evaluation. The specific pattern of marrow abnormality may be helpful in differentiating localized processes from other processes that may affect hematopoietic function in a more widespread or global distribution. In particular, visual inspection of marrow density was more specific for identifying asymmetric marrow density in localized processes than was a quantitative measure of difference between the two femurs (>20 HU).

MRI appearance of the pelvis in the post cesarean-section patient.

Fever in the post-cesarean section patient may indicate the presence of a potentially life-threatening complication, including abscess, ovarian vein thrombosis, and uterine dehiscence. Imaging findings are often utilized to ascertain the presence or absence of such complications. Familiarity with the normal findings in the post-operative period is essential in making this determination. The purpose of this investigation is to describe the MRI appearance of the post-cesarean section pelvis. Over a 67-month period, 50 patients with persistent low-grade fevers following c-section were referred for MR imaging. Imaging was performed 3-10 days post-operatively. Axial T1-weighted and T2-weighted images were acquired in addition to sagittal T2-weighted images. Coronal images were obtained in some cases. Clinical correlation was obtained through the patients charts, confirming discharge of the patients in stable condition. The uterine incision site usually demonstrated findings consistent with subacute hematoma. The anterior uterine myometrium demonstrated enlargement relative to the posterior uterine wall. Bladder flap hematomas were seen in 64% of cases. Three cases (6%) demonstrated parametrial edema and none of these patients demonstrated ovarian vein thrombosis. Two cases of pelvic hematoma were noted. The normal post-c-section incision site may demonstrate increased or decreased signal intensity on T2-weighted images and intact endometrial and serosal layers mitigate against the diagnosis of incisional dehiscence. Bladder flap hematomas occurred in slightly more than half the cases. Parametrial edema and pelvic hematoma can be seen as post-surgical changes.

MRI appearance of clear cell hidradenoma.

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.

Volume fast spin-echo imaging of the cervical spine.

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.

MR appearance of uterine dehiscence in the post-cesarean section patient.

PURPOSE: CT has been shown to be unreliable for detecting uterine dehiscence in the postoperative period after cesarean section (c-section). The purpose of this investigation is to describe the MR appearance of uterine dehiscence in this setting and identify features that distinguish complete from partial dehiscence. METHOD: Over an 82 month period, all charts and MR reports of patients that underwent MRI of the pelvis after c-section were reviewed for uterine dehiscence. Altogether, 55 patients were imaged. Positive cases for dehiscence were retrospectively reviewed by two radiologists. Imaging criteria for complete dehiscence consisted of transmural disruption. Criteria for partial dehiscence consisted of disruption of the endometrial and/or serosal layer, without transmural extension. RESULTS: On MRI, five patients demonstrated abnormalities suggestive of incisional dehiscence. Based on these imaging criteria, two of these showed complete dehiscence that was proven at surgery and three showed findings of partial dehiscence. The optimal imaging plane was perpendicular to the incision. CONCLUSION: MR features may be utilized to identify total uterine dehiscence and may be more effective than CT.

Diagnostic and therapeutic features of facet and sacroiliac joint injection. Anatomy, pathophysiology, and technique.

A diagnosis of exclusion facet syndrome is considered one of the many genuine causes of low back pain. Using careful patient selection, percutaneous facet joint block is a useful diagnostic and therapeutic procedure in the management of lumbar facet syndrome. Sacroiliac joint syndrome appears to be a more tangible entity diagnostically and more amenable to injection. This article addresses the anatomy, pathophysiology, and salient radiographic features of the apophyseal joint, and describes the procedures and techniques for facet as well as sacroiliac joint injection.