Early diagnosis of isthmic spondylolysis with MRI

INTRODUCTION: Early diagnosis of isthmic lumbar spondylolysis cannot always be established on plain radiographs and CT scans, only. In the case presented here, magnetic resonance imaging (MRI) showed typical bone marrow changes in T1- and T2-weighted images, even at an early stage. CASE: A 11-year old female judoka complained of deep lumbar pain with local tenderness to pressure at L3 to S1. Clinically, there was no neurologic deficit. Conventional x-ray showed no abnormalities. In contrast, MRI revealed a locally ill-defined bone marrow oedema in both pars interarticularis of the 5th lumbar vertebra. This was interpreted as the typical MR-tomographic feature of occult stress fracture, which has to be seen as early evidence of isthmic spondylolysis. Complete restitution was achieved after conservative treatment. CONCLUSION: In early spondylolysis--presented here in form of a case report--, changes of MR signal intensity in the pars interarticularis may be detected, even before fracture lines are to be seen on plain radiographs. Further studies are necessary to confirm MRI to be the method of choice for early diagnosis.     

Magnetic resonance imaging and cervical spondylotic myelopathy

Nineteen patients were examined for cervical spondylotic myelopathy with magnetic resonance imaging. Pre- and postoperative magnetic resonance scans were obtained in most cases. Surgical confirmation of the pathological condition was obtained for all 19 patients. On the T2-weighted scans, there was increased signal intensity within the spinal cord at the point of maximal compression. The exact cause of the increased signal intensity on the T2-weighted images is not known, but is suspected to represent edema, inflammation, vascular ischemia, myelomalacia, or gliosis. The increased signal intensity diminished postoperatively in the patients who improved clinically, and remained the same or increased in those whose conditions remained unchanged or worsened after decompression. The authors suggest that these T2-weighted images carry prognostic significance.     

Histologic correlation in magnetic resonance imaging of femoral head osteonecrosis

The present study was undertaken to determine whether a correlation exists between localized magnetic resonance image (MRI) signal behavior and specific histopathologic features of femoral head osteonecrosis. Contiguous, 5-mm coronal MRI sections were compared with corresponding histologic sections from six surgically excised femoral heads. After identifying specific areas of interest on the images, signal intensity was evaluated, both subjectively and objectively, and T1 and T2 relaxation times were calculated. Mean values for these data were compared among the following histologic categories: normal bone, unrepaired dead bone and marrow, unrepaired dead bone with marrow replaced by amorphous debris, and zones of repair. For each type of tissue, MRI signal intensity on T1- and intermediately T2-weighted images behaved in a distinctive fashion. Active repair tissue could be differentiated from both necrotic bone and normal bone by a tendency for the signal to increase in intensity on intermediately T2-weighted images. These findings suggest that MRI may provide a noninvasive means of quantitatively analyzing the volume and spacial distribution of repair tissue in osteonecrotic femoral heads. In clinical practice, such analysis may lead to improvements in disease staging and treatment planning.     

Bone marrow edema syndrome associated with uterine myoma: a case report

A patient with bone marrow edema syndrome of the hip associated with a uterine myoma is presented. A 51-year-old woman could not walk because of severe pain in both hips and had been referred to the authors' institute. Magnetic resonance imaging scans showed abnormal intensity on T1- and T2-weighted images in both femoral heads and a large mass arising from the uterus which was diagnosed as a uterine myoma. A 99mTc-methylene diphosphonate scintigraph showed diffuse uptake in both femoral heads. The pain in both hips decreased shortly after a hysterectomy and the patient could walk without crutches within 2 weeks after the gynecologic surgery. Magnetic resonance imaging scans taken 8 months after surgery showed high signal intensity on T1- and T2-weighted images, indicating normal bone marrow in the femoral heads. To the authors' knowledge, this is the first case report showing a bone marrow edema syndrome of the hip associated with uterine myoma. The pathophysiologic mechanisms for bone marrow edema syndrome of the hip in the current patient and in pregnancy may be identical. More specifically, a large intrapelvic mass may cause an increase of intrapelvic pressure and subsequent blood stasis in both conditions. The current case suggests the possible factors of bone marrow edema syndrome of the hip which need to be investigated.     

Clinical significance of magnetic resonance imaging in the preoperative differential diagnosis of calcifying aponeurotic fibroma

BACKGROUND: Although the clinical and histological features of calcifying aponeurotic fibroma are well described, the magnetic resonance imaging (MRI) findings have been reported for only five cases. The purpose of this study was to describe a series of MRI findings in this rare entity to assess its utility in preoperative and differential diagnosis. METHODS: MRI findings together with the clinical signs and radiographs of six patients with pathologically proven calcifying aponeurotic fibroma were retrospectively reviewed. Distribution, morphology, margins, edematous changes, and relation to the surrounding structures together with signal intensity of each sequence of MRI were evaluated. RESULTS: MRI demonstrated subcutaneous distribution, ill-defined appearance, and a tendency to infiltrate into or adhere to the surrounding tissues. The masses were of isointensity to low intensity on T1-weighted images. T2-weighted images showed heterogeneous high signal intensity with minor areas of isointensity to low signal intensity. Postcontrast T1-weighted images demonstrated heterogeneous intense enhancement. CONCLUSIONS: MRI revealed several features that can contribute to the preoperative differential diagnosis of calcifying aponeurotic fibroma from other fibrous tumors, giant cell tumor of the tendon sheath, or soft tissue sarcoma. As a result, MRI would help orthopedic oncologists plan the surgery for this rare entity.     

磁共振观察宫颈癌放疗后盆部骨髓变化

目的分析宫颈癌放疗中与放疗后盆部骨髓MR改变。探讨MR成像对显示盆部骨髓损伤的临床价值。方法48例经病理证实的宫颈癌患者在放射治疗前及治疗中和治疗后不同时间段行盆腔的轴位SE T1WI，轴位及矢状位TSE T2WI，冠状位SPIR，以及Gd—DTPA增强后T1WI SE的轴位、冠状位、矢状位扫描。在MR图像上观察盆部骨髓在放疗前后的信号改变。结果骨髓信号最早出现改变是在外照射开始后第8天，患者受照剂量在12Gy时。放疗早期，骨髓在T1WI，T2WI及SPIR序列上信号升高，T1WI增强扫描见强化。放疗晚期，骨髓的T1WI，T2WI信号升高程度增加，SPIR序列出现信号降低，T1WI增强扫描，骨髓强化不明显。53％的患者在T1WI、T2WI上，18％的患者在SPIR序列上见照射野外骨髓信号有改变。结论宫颈癌外照射放疗可引起照射野内、外骨髓多种MR信号改变，并有一定规律性，对宫颈癌临床治疗有指导意义。     

Iliacus hematoma and femoral nerve palsy after revision hip arthroplasty: a case report

Femoral nerve palsy occurred in a 65-year-old man after he had undergone a revision total hip arthroplasty using cementless components. The magnetic resonance imaging scan showed a mass in the iliacus muscle. The mass showed increased signal intensity on T1-weighted and T2-weighted spin-echo images and contained linear septa and a nodule. The gadolinium-enhanced T1-weighted image showed a rim of significant enhancement in the nodule. The findings of magnetic resonance images were suggestive of iliacus hematoma and of liposarcoma. The patient underwent surgery, and the mass was identified as an iliacus hematoma. The femoral nerve was stretched by the hematoma. After removal of the hematoma, the nerve palsy was improved completely. Iliacus hematoma may occur after total hip arthroplasty, even without anticoagulant therapy. The hematoma might appear to be a liposarcoma on magnetic resonance imaging scans.     

Osteitis--imaging with magnetic resonance tomography

Between January 1985 and December 1988 41 patients with clinically suspected osteomyelitis were examined by MRI. All cases were proved either by surgery or by clinical follow-up. Evidence of osteomyelitis on MRI consisted of abnormalities of the bone marrow with decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images. Other abnormalities such as degeneration of the intervertebral disc, fatty degeneration of the muscles and thickening of tendon sheaths with fluid were also seen on the same images. The sensitivity of the MRI for the diagnosis of osteomyelitis was 100%, the specificity was 86% and the accuracy 96%. We conclude that MRI is a reliable method in diagnosing osteomyelitis because of its high sensitivity and high specificity.     

Schmorl's nodes and low-back pain

Summary Magnetic resonance imaing (MRI) findings in cases with symptomatic and asymptomatic Schmorl's nodes have been analysed. In all symptomatic cases, the vertebral body marrow surrounding the Schmorl's node was seen as low signal intensity on T1-weighted images and as high signal intensity on T2-weighted images. It was confirmed by histological examination that the MRI findings indicated the presence of inflammation and oedema in the vertebral bone marrow. These MRI findings were not seen in asymptomatic individuals. Inflammatory changes in the vertebral body marrow induced by intraosseous fracture and biological reactions to intraspongious disc materials might cause pain. We postulate that after fracture healing and subsidence of inflammation, the Schmorl's nodes become asymptomatic, in analogy with old vertebral compression fractures. MRI is not only useful in detecting the recently developed Schmorl's nodes but also in differentiating between symptomatic and asymptomatic Schmorl's nodes.     

Magnetic resonance imaging in diagnosis of transient osteoporosis of the hip.

The results of magnetic resonance (MR) imaging in six patients with transient osteoporosis of the hip were reviewed. Short TR/TE (repetition time/echo time) images demonstrated diffusely decreased signal intensity in the femoral head and intracapsular region of the femoral neck. Increased signal intensity was noted with progressive T2 weighting. Bone biopsies were performed in four patients. Histologic findings were nonspecific and included fat necrosis, marrow edema, increased bone resorption, and reactive bone formation. Repeat MR scans in two patients, performed six and eight months after the initial scans, showed an almost complete return to normal marrow signal. All patients became asymptomatic without bony deformity. In the appropriate clinical setting, MR scanning can aid in the diagnosis of transient osteoporosis as the cause of a painful hip.     

Stress osteopathy of the femoral head: 10 military recruits followed for 5-11 years

I present 10 cases of spongious bone injury of the femoral head induced by physical stress. All patients were young military recruits who complained of hip pain from weight bearing which had started during physical exertion. Increased uptake in a radionuclide bone scan was regarded as the criterion for stress osteopathy. 7 hips were radiographically normal. In 3 cases a subcortical lateral cystic lesion of the femoral head was observed. MRI was performed in 6 cases. A decreased signal intensity in T1-weighted images in 5 cases and high signals in T2-weighted and IR signals (2 patients) indicated bone marrow edema. A lateral osteophyte of the femoral head developed in 1 case during 8 years' follow-up. After a median of 6 years, 9 patients still had occasional slight hip pain.     

Central neurocytoma: report of a case

Central neurocytoma is a rare intraventricular tumor recently accepted as a clinicopathological entity. A 21-year-old female was admitted with three-year history of episodic headaches and vomiting, and with rapid deterioration of her left vision over two weeks prior to admission. Computed tomography (CT) scan revealed a marked hydrocephalus and an isodense, mildly enhancing mass in the left lateral ventricle. On magnetic resonance imaging (MRI) scan, T1-weighted images revealed an intraventricular mass of slightly high intensity signal, which contained areas of low intensity signal representing multiple intratumoral cysts. The tumor showed a minimal enhancement with Gd-DTPA. A diagnosis of central neurocytoma was confirmed by an electron-microscopic study of a surgical specimen; there were numerous neuronal cell processes containing microtubules and dense-core vesicles, and a few small intercellular junctions were also identified.     

Histological findings of bone marrow edema pattern on MRI in osteonecrosis of the femoral head

Sequential magnetic resonance imaging (MRI) was performed on a 38-year-old woman with systemic lupus erythematosus who had received corticosteroid and had developed non-traumatic osteonecrosis of the femoral head. The initial MR finding was a band lesion on the T1-weighted image, which had been present before the onset of symptoms. At the onset of symptoms, a diffuse bone marrow edema pattern, with a low signal intensity on T1 and high signal intensity on T2-weighted images, was noted around the band lesion, extending to the femoral neck. Histopathologically, this region was found to consist of serous exudate, focal interstitial hemorrhage, and mild fibrosis, without any evidence of extension of osteonecrosis. It should be noted that extension of a low signal intensity area on MRI after the onset of hip pain may not be the result of the extension of osteonecrosis, but may represent concomitant edema due to collapse. Received: February 25, 2000 / Accepted: May 16, 2000     

Inflammatory pseudotumor of the spleen: CT and MRI findings

Inflammatory pseudotumors rarely occur in the spleen. We report such a case with characteristic computed tomography (CT) and magnetic resonance imaging (MRI) findings. A CT scan showed an isodense nodular mass with gradual mild enhancement on delayed-phase contrast-enhanced images. MRI showed a mass with isointense signal on T1-weighted images and hypointense signal on T2-weighted images. The tumor mass showed progressive inhomogeneous enhancement on gadolinium-enhanced images. The patient received splenectomy, and histologic diagnosis was compatible with inflammatory pseudotumor.     

Transient osteoporosis of the hip. Magnetic resonance imaging

Magnetic resonance (MR) images of seven hips were reviewed in six patients with transient osteoporosis of the hip. The MR images of the affected joint showed increased joint fluid and diffuse signal abnormalities in the marrow of the femoral head, corresponding to a decreased signal intensity on T1-weighted images and an increased signal intensity on T2-weighted images. The MR images at the time of clinical improvement showed regression of the abnormalities. These MR abnormalities reflect the pathophysiology of this condition.     

Computed tomography and magnetic resonance imaging of nonhemorrhagic, metastatic melanoma of the brain--case report.

Malignant melanoma frequently metastasizes to the central nervous system. Characteristic features of such lesions are increased density on computed tomography (CT) and shortening of the T1 and T2 on magnetic resonance (MR) imaging. Intratumoral hemorrhage, rather than melanin, is considered to be mainly responsible for these unique radiological features. The authors report a case involving a nonhemorrhagic, metastatic intracerebral melanoma. CT revealed a high-density mass, and MR imaging demonstrated a hyperintense mass both on T1- and T2-weighted images. These observations suggest that melanin is in fact a major determinant of the increased density on CT scans and the high signal intensity on T1-weighted MR images. On T2-weighted images, the paramagnetic effect appears to vary according to the melanin content.     

Caliceal fistula in kidney transplantation

Caliceal fistula is a rare complication of renal transplantation, which often raises some diagnostic problems. We report the case of a patient in which this complication occurred and in whom the diagnosis could be clearly demonstrated by using magnetic resonance imaging (MRI). On the T1-weighted images, a perirenal collection was depicted by a low signal intensity. On T2-weighted images, the collection appeared with a high signal intensity, and a linear hyperintensity was observed on the internal graft's labium at the level of the inferior pole corresponding to a caliceal fistula arising from the lower pole of the graft. In this setting, the use of MRI is compared with the other diagnostic techniques (sonography, CT scan, nephrogram, scintigraphy). MRI constitutes a progress in imaging of the renal graft by its high definition and the lack of nephrotoxicity. Its place remains, however, to be more precisely defined in the evaluation of a renal graft's complications.     

Traumatic intervertebral disc lesion – magnetic resonance imaging as a criterion for or against intervertebral fusion

Lesions of the intervertebral disc accompanying vertebral fractures are the subject of controversy and discussion regarding the extent and manner of surgical intervention. The question of when to perform disc resection and intervertebral fusion, in particular, has not been answered satisfactorily. In order to evaluate short- and medium-term lesions of the discoligamentous complex associated with thoracolumbar burst fractures, magnetic resonance images made after stabilisation and again after implant removal were compared. Between 1997 and 1998, 20 patients who had suffered thoracolumbar burst fractures (AO classification A3 and B1 [26]) underwent posterior reduction and stabilisation using a Universal Spine System (USS, Synthes, Switzerland) titanium internal fixator. The implant was removed after an average of 10 months. Magnetic resonance imaging (MRI) scans were performed 1 week after both operations, allowing the changes in a total of 40 intervertebral discs adjacent to the fractured vertebral body to be investigated. The analysis was based on signal intensity of the intervertebral disc in T2-weighted scans and on morphological criteria. A total of 81% of the discs with initially normal T2-weighted signal showed the same signal after implant removal; 5 discs with initially increased signal intensity in T2-weighted scans normalised, 5 showed a decrease in intensity and 3 suffered a partial loss of signal. Among the 9 discs with initially decreased T2-weighted signal, only one had normalised by the time the implant was removed. A total of 86% of the 14 morphologically intact discs retained their structural integrity. Of the 25 discs with minor defects, only one could be considered as intact after implant removal, 15 remained the same and 9 deteriorated in structure. No disruption of the fibrous ring or of the posterior longitudinal ligament was observed, nor was there any prolapse of intervertebral discs. When the intervertebral disk is intact and has normal morphology and a normal T2-weighted MRI signal, resection or fusion of the fracture adjacent discs appears unjustified. In our opinion, the results do not support the possibility of predicting degradation in those discs that showed an altered T2-weighted signal after the first operation.     

Magnetic Resonance Imaging of Pressure Sores in Spinal Cord Injured Patients: Accuracy in Predicting Osteomyelitis

Objective:

Identify key magnetic resonance imaging (MRI) features that have a significant correlation with osteomyelitis of pressure ulcers in spinal injury patients.

Design:

Retrospective review study.

Participants:

Adult patients admitted to the National Spinal Injuries Centre with spinal cord injury (SCI) and signs of pressure ulceration investigated with MRI.

Methods:

Analysis of MRI examinations and clinical records collected over a 4-year period. Images were independently assessed by 2 experienced radiologists for osteomyelitis based on assigned predictive indicators including cortical bone erosion, soft tissue edema, deep collections, heterotopic new bone, hip effusion, and abnormal signal change of the marrow.

Results:

Thirty-seven patients underwent 41 MRI scans. The prevalence of osteomyelitis was highly correlated with cortical bone erosion (r = 0.84) and abnormal bone marrow changes on T1-weighted images (r = 0.82).     

Magnetic resonance imaging of a fat embolism of the brain: case report

A 22-year-old man developed fat embolism syndrome. Although a computed tomographic (CT) scan of the brain showed nothing abnormal, a magnetic resonance imaging scan detected scattered spotty areas of low intensity on T1-weighted images and of high intensity on T2-weighted images. Magnetic resonance imaging is thought to be more sensitive than computed tomography in detecting cerebral fat embolism syndrome and correlates well with the clinical course.