MR imaging of tuberculous arthritis: Clinical and experimental studies

Signal-intensity characteristics of magnetic resonance (MR) images were assessed in five patients and in 10 rabbits with tuberculous arthritis. MR imaging findings were compared with histologic findings in the animal study. In both of clinical and experimental cases, tuberculous lesions showed both intermediate and high signal intensity on T2-weighted images, while they showed heterogeneously intermediate signal intensity on T1-weighted images. As T2-weighted images were compared with pathologic specimens, intermediate signal intensity corresponded to caseous necrosis, whereas high signal intensity related to granulomas or effusion. Postcontrast T1-weighted images showed enhancement at the peripheries rather than the centers of tuberculous lesions. These results indicate that tuberculous arthritis should be included in the differential diagnosis when intra-articular lesions with low or intermediate signal intensity are found on T2-weighted images.     

MR imaging of intracranial tuberculomas

Eight patients with intracranial tuberculomas were studied with CT and magnetic resonance (MR) imaging. Large, ring enhancing, solid lesions on CT showed low intensity on T2-weighted images and intermediate intensity on T1-weighted images. Small lesions, with ring enhancement on CT, showed central bright signal on T2-weighted images with a peripheral low intensity rim surrounded by high intensity edema. The MR imaging features of the tuberculomas were found to be distinct from those of abscesses, metastases, and gliomas.     

Tuberculous infection of the wrist: MRI features

OBJECTIVE: The objective of our study was to define the MRI features of tuberculous infection of the wrist. MATERIALS AND METHODS: We present the MRI findings of eight patients with tuberculous infection of the wrist. Spin-echo T1-weighted, gradient-echo T2(*)-weighted, and fast spin-echo T2-weighted sequences were performed for all patients. Gadolinium-enhanced MR images were obtained in seven patients. All images were evaluated for the characteristics of tuberculous infection of the wrist, including the presence of synovial thickening around the joints and tendons, signal intensity of the thickened tenosynovium and synovium on the T2-weighted images, synovial fluid collection in the tendon sheath, small low-signal and nonenhanced foci in the synovial fluid, bone erosion, osteomyelitis, and encasement of the median nerve. RESULTS: The tuberculous infection involved the right (n = 6) and left (n = 2) wrists. All patients had synovial thickening around the flexor and extensor tendons with synovial fluid collection in the tendon sheath. The thickened tenosynovium and synovium revealed low signal intensity on T1-weighted images, intermediate to low signal intensity on T2- and T2(*)-weighted images, and enhancement on contrast-enhanced MR images. The synovial fluid showed intermediate to low signal on T1-weighted images and homogeneous or heterogeneous high signal intensity on T2- and T2(*)-weighted images. Multiple small foci of low signal intensity and nonenhancement scattered in the synovial fluid were present in seven patients. Bone erosion occurred in seven patients, osteomyelitis was seen in six patients, and encasement of the median nerve was found in three patients. CONCLUSION: Characteristic MRI findings of tuberculous infection of the wrist include synovial thickening around the flexor and extensor tendons and synovial fluid collection that contains small low-signal and nonenhanced foci in the tendon sheath. Bone erosion, osteomyelitis, and median nerve encasement are also frequently present. These characteristic manifestations are helpful in diagnosing this disease entity.     

Idiopathic bone marrow edema lesions of the femoral head: predictive value of MR imaging findings.

PURPOSE: To determine the frequency of several subchondral magnetic resonance (MR) imaging features observed in bone marrow edema lesions of the femoral head and to determine their value for differentiation of irreversible from transient lesions. MATERIALS AND METHODS: The authors reviewed MR images of 72 femoral head lesions in 42 men and 25 women (median age, 48 years) with equivocal radiographic findings and bone marrow edema seen at MR imaging (T1- and T2-weighted images in all patients and contrast material-enhanced T1-weighted images in 39 patients). Follow-up MR images showed 57 lesions to be transient and 15 to be irreversible. The presence and size of subtle subchondral features observed on initial MR images were compared for both types of lesion. RESULTS: Lack of any additional subchondral change on T2-weighted or contrast-enhanced T1-weighted images had 100% positive predictive value for transient lesions. For irreversible lesions, presence of a subchondral area of low signal intensity at least 4 mm thick or 12.5 mm long had positive predictive values of 85% and 73%, respectively, on T2-weighted images and 87% and 86%, respectively, on contrast-enhanced T1-weighted images. CONCLUSION: Careful assessment of subchondral changes enables confident differentiation between early irreversible lesions and transient bone marrow edema lesions.     

Single shot fast spin echo diffusion-weighted MR imaging of the spine; Is it useful in differentiating malignant metastatic tumor infiltration from benign fracture edema?

PURPOSE: This study aims to evaluate the usefulness of single shot fast spin echo diffusion-weighted MR imaging (DWSSFSE) in differentiating malignant metastatic tumor infiltration of vertebral bone marrow from benign vertebral fracture edema. MATERIALS AND METHODS: Forty-six consecutive patients with 59 acute osteoporotic or traumatic vertebral fractures (mean age = 59) and 31 patients with 98 vertebral metastasis including 20 pathologic fractures (mean age = 53) were included in this study. Diffusion-weighted MR images were obtained by single-shot fast spin echo technique with diffusion gradient (b = 500 s/mm2, TR/TE: 5002/99) by using a 1.5 T MR scanner (Signa MR/i; GE Medical Systems, Milwaukee, WI, USA). T1- and T2-weighted images and short inversion time inversion-recovery (STIR) images were available in all 157 lesions, while contrast-enhanced images were available in 98 metastatic lesions. We evaluated signal intensity patterns on DWSSFSE in 157 lesions, which showed low signal intensity on T1-weighted images in both benign fractures and metastasis. The lesions on DWSSFSE were categorized as low, intermediate, and high signal intensity relative to presumed normal vertebra by concordant inspection of two experienced musculoskeletal radiologists. RESULTS: In benign fractures, DWSSFSE images showed low signal intensity in 56 vertebrae (95%) in 43 patients (93%) and intermediate signal intensity in only 3 vertebrae (5%) in 3 patients (7%). On the other hand, metastases most commonly had low signal intensity in 57 vertebrae (58%) in 25 patients (80%), intermediate signal intensity in 35 vertebrae (36%) in 16 patients (52%), and high signal intensity in 6 vertebrae (6%) in 3 patients (10%). Thus, intermediate and high signal intensities are far more common than benign fractures. Such differences in signal intensity were statistically significant (chi-square test, P < .05). High or intermediate signal intensity on DWSSFSE was highly specific for the diagnosis of metastatic tumor infiltration of the spine (sensitivity: 42%; specificity: 95%; true positive rate: 93%; false negative rate: 52%). CONCLUSIONS: DWSSFSE of the spine may be useful in differentiating metastatic tumor infiltration of vertebral bone marrow from benign fracture edema.     

Unusual manifestations of vertebral osteomyelitis: intraosseous lesions mimicking metastases

BACKGROUND AND PURPOSE: Vertebral osteomyelitis can have different imaging manifestations. The purpose of this study was to demonstrate the unusual MR imaging patterns of vertebral osteomyelitis with intraosseous lesions mimicking metastases.MATERIALS AND METHODS: From September 2000 to August 2007, 7 patients were selected from our data base of 214 patients with confirmed vertebral osteomyelitis and MR images. All of those having misinterpreted MR imaging reports and unusual imaging patterns were analyzed. The presence of a peripheral curvilinear area of low signal intensity in an osseous lesion (the rim sign) and a peripheral rim of high signal intensity on T2-weighted images around an osseous lesion (the halo sign) was evaluated. Follow-up MR imaging studies were performed in all patients.RESULTS: The patients were 5 men and 2 women, with an age range of 42–80 years. MR imaging findings of those with vertebral osteomyelitis showed a solitary lesion in 2 and multiple lesions in 5 patients. The intraosseous lesions revealed low signal intensity on T1-weighted images, mixed or high signal intensity on T2-weighted images, high signal intensity on short τ inversion recovery images, and global or marginal enhancement. The rim sign was found in 6 (86%) patients; halo sign, in 7 (100%); preserved intervertebral disks, in 7 (100%); and limited paraspinal or epidural inflammation, in 6 (86%). Images of all patients demonstrated healing or almost healed changes on the follow-up MR imaging studies.CONCLUSION: Vertebral osteomyelitis can have MR imaging patterns mimicking osseous metastases. Recognition of these unusual imaging manifestations, together with clinical and histopathologic analysis, may aid in reaching the correct diagnosis.

MR imaging has become the valuable technique of choice for early detection of osteomyelitis because of its excellent contrast resolution between the abnormal and normal bone marrow.^1–5 In pyogenic vertebral osteomyelitis and spondylodiskitis, several MR imaging characteristics have been described, including decreased signal intensity on T1-weighted images, increased signal intensity on T2-weighted images, and enhancement on contrast-enhanced MR images in the disk and adjacent vertebral bodies; erosion or destruction of at least 1 vertebral endplate; decreased disk height and an absent intranuclear cleft; and paraspinal and/or epidural inflammatory soft tissue, abscess formation, or both.^4–9 Relative preservation of the disk morphology and signal intensity has been reported in tuberculous and certain fungal infections.^10–12The route of hematogenous spread of microorganisms or septic emboli might involve osseous changes similar to those of hematogenous spread of other etiologies, such as malignant cells when the microorganisms are dislodged in the end arterioles. Thus, it is sometimes difficult to make the differential diagnosis of septic emboli versus osseous metastases. The unusual manifestations of vertebral osteomyelitis with MR imaging patterns of septic emboli mimicking osseous metastases, to our knowledge, have not been previously described in the literature. Therefore, the purpose of this study was to demonstrate and analyze the unusual MR imaging patterns of misdiagnosed vertebral osteomyelitis with intraosseous lesions, which may mimic osseous metastases.     

Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow

PURPOSE: To find any differential magnetic resonance (MR) imaging findings between septic arthritis and transient synovitis in pediatric patients. MATERIALS AND METHODS: The MR imaging findings in nine pediatric patients with septic arthritis and 14 with transient synovitis were retrospectively studied. The diagnoses were made by means of joint aspiration with bacteriologic study, arthrotomy, and clinical evaluation. MR imaging findings were analyzed with emphasis on the grade of joint effusion and alterations in signal intensity in the soft tissue and bone marrow of the affected hip joint. RESULTS: Signal intensity alterations in bone marrow (i.e., low signal intensity on fat-suppressed gadolinium-enhanced T1-weighted spin-echo images and high signal intensity on fat-suppressed T2-weighted fast spin-echo images) were seen in eight of nine patients with septic arthritis. These signal intensity alterations consisted of mild juxtaarticular changes in six patients without osteomyelitis and extensive changes in the femoral head and neck in two patients with coexistent osteomyelitis. Signal intensity alterations in bone marrow were not seen in the 14 patients with transient synovitis. CONCLUSION: Signal intensity alterations in the bone marrow of the affected hip joint are useful in the differentiation of septic arthritis from transient synovitis.     

Eosinophilic granuloma: MRI manifestations

The appearance on magnetic resonance imaging (MRI) of 16 cases of pathologically proven eosinophilic granuloma were reviewed retrospectively and correlated with the radiographic appearance of the lesion. The most common MR appearance (ten cases) was a focal lesion, surrounded by an extensive, ill-defined bone marrow and soft tissue reaction with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, considered to represent bone marrow and soft tissue edema (the flare phenomenon). The MRI manifestations of eosinophilic granuloma, especially during the early stages, are nonspecific, and may simulate an aggressive lesion such as osteomyelitis or Ewings sarcoma, or other benign bone tumors such as osteoid osteoma or chrondroblastoma.     

Magnetic resonance imaging findings in patients with medial epicondylitis

Objective To compare the MR imaging findings of 13 patients with clinically diagnosed medial epicondylitis with the MR imaging findings of 26 patients of similar age with no clinical evidence of medial epicondylitis.Design and patients The study group consisted of 13 patients with clinically diagnosed medial epicondylitis. The control group consisted of 26 patients of similar age with no clinical evidence of medial epicondylitis. The medical records and MR imaging findings of these patients were retrospectively reviewed by two fellowship-trained musculoskeletal radiologists.Results Eleven of the 13 patients in the study group had thickening and increased signal intensity of the common flexor tendon on both T1-weighted and T2-weighted images. The remaining two patients in the study group had soft tissue edema around a normal-appearing common flexor tendon. Twenty-one of the 26 patients in the control group had a normal-appearing common flexor tendon on MR imaging. Three patients in the control group had a thickened common flexor tendon which was of intermediate signal intensity on T1-weighted images but of uniform low signal intensity on T2-weighted images. Two patients in the control group had a thickened common flexor tendon which was of intermediate signal intensity on both T1-weighted and T2-weighted images. None of the patients in the control group had soft tissue edema around the common flexor tendon.Conclusion MR imaging findings of patients with clinically diagnosed medial epicondylitis included thickening and increased T1 and T2 signal intensity of the common flexor tendon and soft tissue edema around the common flexor tendon. The presence of intermediate to high T2 signal intensity or high T2 signal intensity within the common flexor tendon and the presence of paratendinous soft tissue edema were the most specific findings of medial epicondylitis on MR imaging.     

Magnetic resonance imaging of myositis ossificans: analysis of seven cases

Myositis ossificans typically presents as soft tissue swelling with progressive ossification on radiographs. Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images.We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass.     

MR imaging of skeletal metastases from medulloblastoma

The findings of MR imaging in 3 patients with bone metastases from medulloblastoma are reported. The first patient showed focal lesions of low signal intensity on T1-weighted spin echo images at a time when bone scintigraphy was negative for metastases. This patient later developed extensive osteosclerotic lesions visible on plain films. The bone marrow of the second patient showed diffuse low signal intensity on T1-weighted images. After chemotherapy the signal intensity of the bone marrow increased which correlated with a return of normal hematopoietic tissue. A response to chemotherapy was also found on MR imaging and repeat bone marrow biopsies in a third patient. A consistent finding was a low signal intensity on pre-gadolinium images, but the pattern (focal or diffuse abnormal signal intensity) was different in each patient. To our knowledge, this is the first report on MR imaging findings in bone metastases from medulloblastoma.     

Osteomyelitis: characteristics and pitfalls of diagnosis with MR imaging

Prospective and retrospective magnetic resonance (MR) imaging (0.35-T) interpretations were compared with final diagnoses in 110 patients suspected to have osteomyelitis. Diagnostic criteria of dark marrow on T1-weighted images and bright marrow on short-tau inversion-recovery images yielded a prospective sensitivity of 98% and a prospective specificity of 75%. Sixty percent of uncomplicated septic joint effusions demonstrated abnormal marrow signal intensity that was mistaken for osteomyelitis. Retrospective review revealed that overall specificity could be improved to 82% without loss of sensitivity if increased marrow signal intensity on T2-weighted images were included as an additional criterion. Specificity may be further increased by use of knowledge of morphologic patterns that distinguish various forms of osteomyelitis. Ten patients (9%) had potential pitfall diagnoses (eg, fracture, infarction, healed infection) that mimic osteomyelitis. MR imaging can be sensitive and specific for osteomyelitis if characteristic appearances and pitfall diagnoses are incorporated into the diagnostic criteria.     

Stress fractures: MR imaging

Five cases of stress fracture were studied with high-field-strength magnetic resonance (MR) imaging. In all cases, MR images showed bandlike areas of very low signal intensity in the intramedullary space, which were continuous with the cortex. These findings corresponded in location to the sites of fracture or new bone formation noted on radiographs. Surrounding areas of decreased signal intensity in the marrow space were also consistently seen on T1-weighted images. In three cases, prominent intramedullary areas of high signal intensity were noted on T2-weighted images obtained within 3 weeks of the onset of symptoms. Juxtacortical and/or subperiosteal areas of high signal intensity were also seen on T2-weighted images in two cases. Characteristic MR findings may distinguish stress fracture from occult intraosseous fracture.     

Bone bruises: MR characteristics and histological correlation in the young pig

PURPOSE: To correlate magnetic resonance (MR) signal characteristics of bone bruises with histological findings. MATERIALS AND METHODS: In 14 tibiae of young pigs, bone bruises were created in the proximal tibial metaphysis. The signal intensity seen on the MR images were correlated with histological findings. The following findings were evaluated: (a) changes of signal intensity on the tibiae; (b) changes of histology on the tibiae; and (c) changes of (a) and (b) on follow-up examinations. RESULTS: We observed three types of injuries on T1-weighted images: focal or diffuse low signal, normal signal and linear low signal intensities. Severe hemorrhagic areas showed low signal intensities on all sequences of MR imaging. Fast spin-echo (FSE) T2-weighted images showed a more distinct low signal intensity than T1-weighted images. FSE short tau inversion recovery (STIR) and FSE fat saturated (FSE-FS) T2-weighted images showed similar signal intensities with FSE T2-weighted images. FS T1-weighted enhanced images showed low signal intensities with variable enhancements. Upon histological examination, hemorrhages and edemas were prominent at the subcortical areas of the contusion sites. The areas of dense, low signal intensities in all imaging sequences showed signs of severe hemorrhage. The areas of diffuse low signal and enhanced areas showed mixed areas of hemorrhages and edemas. Follow-up MR imaging showed evolution of the processes of hemorrhages and edemas with fatty marrow changes. CONCLUSIONS: MR imaging can depict changes in the bone marrow resulting from direct injury to the bone. MR imaging is a useful tool for evaluating the evolution of bone bruises.     

Tophaceous gout of the spine: MR imaging features

AIM: To define the magnetic resonance (MR) imaging features of tophaceous gout of the spine. MATERIALS AND METHODS: We present the MR imaging examinations of 4 patients with spinal tophaceous gout. Spin-echo T1-weighted and fast spin-echo T2-weighted images were obtained for all patients, and 2 patients had gadolinium-enhanced MR imaging studies. Corresponding computed tomography (CT) was performed in one patient. All images were evaluated for the characteristics of the gouty tophi. RESULTS: The gouty tophi were located at the lower thoracic (n=1) and lumbar (n=3) levels. All tophi yielded homogeneous intermediate to low signal on T1-weighted images and variable signal intensity on T2-weighted images, comprising small foci of very low signal intensity on all sequences. Gadolinium-enhanced MR imaging studies revealed homogeneous enhancement or heterogeneous peripheral enhancement. Diffuse stippled calcifications were found in the tophi on CT images. Periarticular tophi with juxtaarticular bony erosions around facet joints occurred in 3 patients. CONCLUSION: Spinal tophaceous gout should be considered in the differential diagnosis when periarticular deposits contain very low signal foci on all MR imaging sequences.     

Transient bone marrow edema of the talus: MR imaging findings in five patients

OBJECTIVE: To describe the MR findings of transient bone marrow edema (TBME) of the talus and to address the differential diagnostic considerations. DESIGN AND PATIENTS: The imaging findings of TBME of six tali were retrospectively reviewed in five patients with a clinical history of pain without trauma. Inclusion criteria were MR imaging findings that, when compared with clinical data and results of follow-up assessment, allowed the diagnosis of TBME. MR imaging, standard radiography, and bone scintigraphy were performed. The images were reviewed with particular attention to the pattern and distribution of abnormal marrow signal intensity as well as associated findings. RESULTS: In four cases the entire talus was involved, and in two cases only a portion of the bone was affected. No fractures were detected. MR imaging demonstrated diffuse decreased signal intensity of the marrow on T1-weighted images with corresponding increased signal intensity on T2-weighted images. In all six cases MR imaging detected associated findings, which included joint effusion and soft tissue edema. All patients improved clinically with conservative therapy over a period of 6 months to 1 year. CONCLUSIONS: Although unusual, TBME can involve the talus. Marrow edema without evidence of a fracture and in the absence of history of trauma is a characteristic MR imaging feature, allowing confident diagnosis and institution of conservative therapy.     

SSH-EPI diffusion-weighted MR imaging of the spine with low b values: is it useful in differentiating malignant metastatic tumor infiltration from benign fracture edema?

Objective  Conventional MR sequences are sometimes not helpful in differentiating benign from pathologic fractures. Our aim was to evaluate the usefulness of single-shot echo-planar imaging sequences (diffusion-weighted imaging (DWI)/SSH-EPI) with low b value in differentiating malignant metastatic tumor infiltration of vertebral bone marrow from benign vertebral fracture edema. Materials and methods  A total of 47 patients, 20 with benign fractures and 27 with tumor infiltration, were included in this prospective study. Diffusion-weighted MR images were obtained by single-shot echo-planar imaging technique with diffusion gradient (b = 300 s/mm²; TR/TE, 1,400/100), using a 1.5 T MR scanner. T1- and T2-weighted images and short inversion time inversion-recovery images were available for all 64 lesions. The lesions on DWI/SSH-EPI were categorized as having hypo-, iso-, or hyperintense signal intensity relative to normal vertebrae by two experienced radiologists. Results  We evaluated signal intensity patterns on DWI/SSH-EPI in 64 lesions, which showed low signal intensity on T1-weighted images in both benign fractures and metastasis. With the exception of sclerotic metastases in two patients, malignant metastatic tumor infiltration was hyperintense with respect to normal bone marrow on diffusion-weighted images; all but four benign vertebral fractures were isointense with respect to normal bone marrow. Conclusion  Single-shot echo-planar imaging sequences (DWI/SSH-EPI) with low b value provided excellent distinction between metastatic tumor infiltration and benign vertebral fracture edema. Hyperintense signal intensity on DWI/SSH-EPI was highly specific for the diagnosis of metastatic tumor infiltration of the spine.     

Adnexal masses caused by pelvic inflammatory disease: MR appearance.

PURPOSE: To describe the morphologic and signal intensity characteristics of inflammatory adnexal masses in magnetic resonance (MR) images. MATERIALS AND METHODS: MR images of 15 patients with a total of 20 confirmed inflammatory adnexal masses were analyzed retrospectively. RESULTS: The findings obtained from MR imaging were as follows: lesions have ill-defined borders; ill-defined areas of high intensity signals surround the masses on T(2)-weighted images; a "rim" at the innermost layer of the cyst wall exhibits high signal intensity on T(1)-weighted images and low intensity on T(2)-weighted images; secondary changes in the surrounding fat plane and bowel loops are extensive; and adhesions are dense. These findings reflect the basic characteristics of the inflammatory process, which are edema caused by increased permeability and highly vascularized granulation tissue caused by the strong tendency to repair. CONCLUSION: MR imaging findings well reflect the basic pathological process of inflammation, and inflammatory adnexal masses are associated with relatively specific appearances in MR images. MR imaging can be a problem-solving alternative in the diagnosis of inflammatory adnexal masses.     

Dark t1 bone marrow

Bone marrow contains fat and water. Using magnetic resonance (MR) T1-weighted images, fat appears light gray and water appears dark gray. Black or low signal structures include normal cortical bone, bone islands, hemosiderin deposits, calcification, ossification, metal artifact, gas, and foreign material. Reactivation of bone marrow reduces the signal of fatty marrow. Additional sequences and supplementary imaging with conventional radiographs and computed tomography are often helpful in determining the nature of the low signal lesions. Genetic bone disorders such as melorheostosis and other syndromes may give low signal lesion in a typical and often diagnostic pattern. MRI is an important method of showing the fracture line as a low signal lesion on T1-weighted images and is the preferred imaging method when conventional radiographs are unhelpful and fracture is suspected. Infection will cause edema and later sclerosis and necrosis with a mixed low and high signal pattern. Infarction will cause a mixed pattern depending on the stage of the process, but this includes low signal on T1-weighted images. Ossification and calcification in primary and secondary tumors appear as low signal areas on T1-weighted images. Recognition and understanding of lesions that cause low signal on T1-weighted images is an important tool when interpreting MR images.     

Benign vertebral hemangioma: MR-histological correlation

Objective: To explain the magnetic resonance (MR) appearance of benign vertebral hemangioma by correlating MR and histological findings from autopsy specimens. Design: Sagittal T1- and T2-weighted spin-echo images were obtained in 83 spine specimens. Focal lesions consistent with vertebral hemangioma at macroscopic examination of sagittal anatomical sections were sampled for histological and quantitative analysis. At histology, the proportion of surface area occupied by adipocytes, vessels and edema, and hematopoietic cells was determined (point-counting method) in normal marrow areas and in lesion areas whose signal intensity was either high and intermediate (pattern A) or intermediate and high (pattern B) on T1- and T2-weighted images, respectively. Results: Nine lesions were sampled and corresponded to cavernous hemangioma at histology. The proportion of surface area occupied by adipocytes was statistically significantly higher in pattern A (78.1%) than in pattern B lesion areas (42.7%) and than in normal marrow areas (47.5%). The proportion of surface area occupied by vessels and interstitial edema was statistically significantly higher in pattern B (47.0%) than in pattern A lesion areas (15.5%) and than in normal marrow areas (0). Conclusion: The presence of high signal intensity on T1- or T2-weighted images of vertebral hemangioma is related to the amount of adipocytes or vessels and interstitial edema, respectively. Received: 8 September 2000 Revision requested: 29 December 2000 Revision received: 27 March 2001 Accepted: 18 April 2001