Magnetic resonance imaging of cartilaginous tumors: a retrospective study of 79 patients

Objective: Hyaline cartilaginous tumors are characterized by extremely high signal intensity on T2-weighted images. Recently, some distinctive MR features of cartilaginous bone tumors were reported in small series. Low signal intensity septa surrounding high signal intensity cartilage lobules were seen on T2-weighted images in low-grade chondrosarcomas. On spin-echo T1-weighted images after Gd contrast injection, marked ‘septal’ or ‘ring-and-arc’ enhancement was observed in low-grade chondrosarcomas and enchondromas. The purpose of this study was to determine sensitivity and specificity of these MR findings in diagnosis of cartilaginous tumors, and to assess the value of MR in diagnostic workup of these lesions. Materials and methods: Retrospective evaluation of MR findings in 79 cartilaginous tumors and in 79 non-cartilaginous tumors. All lesions were biopsy proven. Each MR examination was independently reviewed by two experienced radiologists without knowledge of clinical data, radiographic and/or CT findings, or histological diagnosis. All lesions were evaluated for morphology (lobular or non-lobular), presence of a high signal intensity mass on T2-weighted images, presence of low signal intensity septa separating high signal intensity lobules on T2-weighted images, and evidence of septal (‘ring-and-arc’) enhancement.Results: None of the reviewed parameters is useful in diagnosing osteochondromas. Since osteochondromas have a characteristic appearance on plain radiography, the value of MR imaging in the workup of these lesions remains limited. MR findings in enchondromas have a low specificity and a low sensitivity. Low-grade chondrosarcomas, often hard to diagnose on plain radiography and difficult to differentiate from enchondromas, are characterized by the MR tandem of ‘low signal intensity septa on T2-weighted images’ together with ‘septal or ring-and-arc enhancement’ (sensitivity 92.3%, specificity 76.5%). High-grade chondrosarcomas are easily recognized on plain radiography. Conclusions: In differentiating cartilaginous from non-cartilaginous tumors, MR features are highly specific but lack sensitivity. Grading potentials of MR parameters are promising due to the high accuracy in diagnosing low-grade chondrosarcomas.     

Magnetic resonance imaging in coccidioidal arthritis

 Objective. The authors assessed the MRI findings of appendicular coccidioidal arthritis. Design. T1- and T2-weighted MR images of affected joints, both with and without intravenous gadopentetate dimeglumine, were performed in nine adult patients (ten studies) and evaluated by three masted readers, using a four-point certainty scale for: synovial abnormality, articular cartilage loss, subarticular bone loss, abnormal marrow signal, enhancement of osseous and articular structures, and assessment of disease activity. Findings were correlated with biopsy results or clinical course. Results. Eight patients had active and one had inactive arthritis, involving the knee (five patients), ankle (two patients), and elbow (one patient). Synovial complex was the most common finding in active arthritis (P<0.025). Cartilage and subarticular bone loss were seen 56% and 89% of patients with active disease, respectively. Abnormal marrow signal was uncommon (two patients). All cases showed synovial and/or osseus enhancement. Conclusions. MRI findings in coccidiodal arthritis are described. Enhancement of thickened synovium and erosions was seen after intravenous gadopentetate.     

MRI of bone tumors: Fast STIR imaging as a substitute for T1-weighted contrast-enhanced fat-suppressed spin-echo imaging

PURPOSE: To compare the usefulness of short inversion recovery (STIR) and T1-weighted, contrast-enhanced, fat-suppressed (T1W-CEFS) sequences for the evaluation of bone tumors. MATERIALS AND METHODS: Eighteen patients with 19 bone tumors who underwent both STIR and T1W-CEFS imaging were evaluated. The tumors were categorized in pairs as follows: bone marrow and soft-tissue components, benign and malignant tumors, and tumors with and without mineralization. The signal difference-to-noise ratio (SDNR), signal-to-noise ratio (SNR), and tumor volume were calculated in each group. An additional qualitative analysis was performed by means of the ratings of imaging contrast. RESULTS: The mean SDNRs of all bone marrow components and bone marrow components without mineralization were significantly higher on fast STIR images than on T1W-CEFS images (P < 0.05). There was no significant difference in the mean SDNR and SNR of the other group (surrounding soft tissue components, bone marrow components with mineralization, benign and malignant lesions) between fast STIR images and T1W-CEFS images. The mean volume of the tumors was significantly higher with STIR than with the T1W-CEFS sequence (P < 0.05). CONCLUSION: The STIR sequence should be used instead of T1W-CEFS imaging for the evaluation of bone tumors.     

Ferumoxtran-10-enhanced MR imaging of the bone marrow before and after conditioning therapy in patients with non-Hodgkin lymphomas

To quantify permeability changes of the “blood–bone marrow barrier” (BMB) and to detect malignant bone marrow infiltrations before and after conditioning therapy for subsequent leukapheresis using ferumoxtran-10-enhanced magnetic resonance (MR) imaging. Twenty-two patients with malignant non-Hodgkin lymphomas (NHL), including 9 patients (group A) before and 13 patients (group B) after conditioning therapy, underwent MR of the spine before and after infusion of ferumoxtran-10 (0.045 mmol Fe/kg BW). Pulse sequences comprised dynamic T1-GE and pre- and post-contrast T1-SE and STIR sequences. Dynamic ΔSI-data were correlated with the quantity of mobilized CD34+ cells. In addition, the number of focal bone marrow lesions was compared before and after ferumoxtran-10 administration. Dynamic ΔSI-data were higher in group B than in group A, indicating an increased BMB permeability after conditioning therapy. However, ΔSI-data did not correlate with the quantity of mobilized CD34+ cells. Ferumoxtran-10-enhanced STIR images demonstrated a significant signal decline of the normal, non-neoplastic bone marrow and a significantly increased detection of focal neoplastic lesions compared to pre-contrast images (P<0.05). Ferumoxtran-10 depicted the bone marrow response to conditioning therapy by an increase in BMB-permeability, which, however, did not correlate with the number of mobilized CD34+ cells. Ferumoxtran-10 improved the detection of focal bone marrow lesions significantly (P<0.05).     

Comparison of STIR and spin-echo MR imaging at 1.5 T in 45 suspected extremity tumors: lesion conspicuity and extent

Short inversion time inversion recovery (STIR) imaging and a double-echo spin-echo (SE) sequence at 1.5 T in 45 sequential patients with suspected extremity tumors were compared to assess the number of lesions detected, subjective conspicuity of lesions, approximate volume of abnormality detected in each lesion, and identification of peritumoral brightening in tissues adjacent to each lesion. STIR sequences enabled detection of all 45 lesions; 44 were detected with the SE sequence. Tumor appeared most conspicuous on STIR images in 35 patients (78%) and was most conspicuous on SE images in 10 patients (22%). Peritumoral brightening, which indicated either peritumoral edema or microscopic tumor infiltration, was detected in 20 patients but was detected only with STIR sequences in nine patients. It is concluded that, although STIR and SE sequences are comparable for lesion detection in the extremities, most lesions appear more conspicuous with STIR. STIR may enable detection of a greater volume of abnormality than SE sequences and may therefore have important implications for local staging and surgical and radiation therapy planning.     

Comparison of diffusion-weighted images using short inversion time inversion recovery or chemical shift selective pulse as fat suppression in patients with breast cancer

Purpose  Fat suppression is essential for diffusion-weighted imaging (DWI) in the body. However, the chemical shift selective (CHESS) pulse often fails to suppress fat signals in the breast. The purpose of this study was to compare DWI using CHESS and DWI using short inversion time inversion recovery (STIR) in terms of fat suppression and the apparent diffusion coefficient (ADC) value. Materials and methods  DWI using STIR, DWI using CHESS, and contrast-enhanced T1-weighted images were obtained in 32 patients with breast carcinoma. Uniformity of fat suppression, ADC, signal intensity, and visualization of the breast tumors were evaluated. Results  In 44% (14/32) of patients there was insufficient fat suppression in the breasts on DWI using CHESS, whereas 0% was observed on DWI using STIR (P < 0.0001). The ADCs obtained for DWI using STIR were 4.3% lower than those obtained for DWI using CHESS (P < 0.02); there was a strong correlation of the ADC measurement (r = 0.93, P < 0.001). Conclusion  DWI using STIR may be excellent for fat suppression; and the ADC obtained in this sequence was well correlated with that obtained with DWI using CHESS. DWI using STIR may be useful when the fat suppression technique in DWI using CHESS does not work well.     

Magnetic resonance imaging features of fractures using the short tau inversion recovery (STIR) sequence: correlation with radiographic findings

The MRI characteristics of fractures have been described on the basis of spin echo (SE) images emphasizing T1 and T2 contrast. These previous studies were carried out for injuries in which radiographic proof was often lacking. In comparison with SE images, short tau inversion recovery (STIR) images have been shown to provide superior contrast between normal and abnormal marrow. To determine the MRI characteristics of fracture using STIR pulse sequences, we reviewed 28 patients who had radiographic evidence of fracture and were examined with T1-weighted SE and STIR sequences. MRI marrow signal abnormalities were demonstrated at all fracture sites ranging in age from less than 24 h to 8 weeks. The extent of marrow signal abnormalities exceeded the size of corresponding radiographic findings of fracture in all cases. The MRI features of fractures on T1-weighted SE images consisted of irregular intramedullary zones of hypointensity. On STIR images a corresponding zone of hyperintensity extended to the outer cortical margin. Intramedullary lines of hypointensity extending to the inner cortical margin were identified within the hyperintense marrow abnormality on STIR images in 64% of the fractures. The results of this study show that MRI using T1-weighted SE and STIR sequences can consistently demonstrate prominent signal abnormalities at fracture sites including those in which radiographic signs are subtle.     

Enchondroma vs. chondrosarcoma: A simple,easy-to-use,new magnetic resonance sign

Introduction

There is no clear radiologic or pathologic agreement on the differences between enchondroma and conventional chondrosarcoma, which has huge therapeutic consequences. Microscopically, an enchondroma is composed of “islands of intramedullary hyaline cartilage surrounded by marrow fat”, and a chondrosarcoma a “diffuse cartilaginous replacement (invasion) of the marrow which leads to complete ‘trapping’ of host lamellar bone trabeculae.” The marrow around islands of cartilage should be detectable on magnetic resonance imaging (MR). Enchondroma may be the precursor of chondrosarcoma; benign cartilaginous islands are often seen microscopically at the periphery of chondrosarcoma. We attempted to detect these islands at the periphery of chondrosarcomas on MR and correlate them microscopically.

Materials and methods

We examined our database for all patients with a chondrosarcoma of the long and flat bones between 1990 and 2007. Only those with a preoperative MR who underwent an en bloc resection were included, yielding 32 patients. We looked for low-signal islands surrounded by high (fat) signal on T1-weighted images, and high-signal islands surrounded by low signal on T2-weighted fat saturated images at the periphery of the main tumour mass. Microscopic correlation was performed in all cases.

Results

On microscopy, there were 23 conventional chondrosarcomas, nine dedifferentiated. Peripheral islands surrounded by fat were detected on MR in 19 cases, corresponding to benign cartilage in 18 cases and to the benign scar of a needle biopsy tract in one. There were no peripheral islands detected radiographically or microscopically in 13 cases.

Conclusion

Cartilaginous islands microscopically detected at the periphery of some chondrosarcomas are easily and reliably diagnosed on MR.     

Early and late bone-marrow changes after irradiation: MR evaluation

Knowledge of the chronologic evolution of bone-marrow changes during and after radiation therapy is essential in differentiating normal postradiation changes from other marrow abnormalities. The appearance of the lumbar vertebral bone marrow was studied on 55 serial spin-echo and short-T1 inversion-recovery (STIR) MR images obtained in 14 patients receiving radiation therapy for Hodgkin disease, seminoma, or prostate carcinoma. Images were obtained before, at weekly intervals during, and at various monthly intervals up to 14 months after a 3- to 6-week course of fractionated paravertebral lymph-node irradiation of 1500-5000 rad (15-50 Gy). During the first 2 weeks of therapy, there was no definite change in the appearance of the marrow on spin-echo images; however, there was an increase in signal intensity on the STIR images, apparently reflecting early marrow edema and necrosis. Between weeks 3 and 6, the marrow showed an increasingly heterogenous signal and prominence of the signal from central marrow fat, shown best on T1-weighted images. Late marrow patterns (6 weeks to 14 months after therapy) varied and consisted of either homogenous fatty replacement or a band pattern of peripheral intermediate signal intensity, possibly representing hematopoietic marrow surrounding the central marrow fat. No focal marrow lesions or soft-tissue edema were identified during the course of radiation therapy; their presence should raise the possibility of the presence of a pathologic process other than radiation change. These data suggest that MR can detect radiation-induced marrow changes as early as 2 weeks after starting therapy, and that there are at least two distinct types of late marrow MR patterns.     

Diagnosis of osteomyelitis by MR imaging

Bone scans are highly sensitive for the diagnosis of acute osteomyelitis, but the difficulty of separating bone-marrow processes from soft-tissue disease limits the specificity and accuracy. A diagnostic technique capable of distinguishing bone-marrow processes from soft-tissue disease would improve the diagnostic accuracy of osteomyelitis. To evaluate the use of MR in the diagnosis of osteomyelitis, MR examinations were performed in 35 patients with suspected acute osteomyelitis. Twelve of these were proved to have osteomyelitis either by surgery (nine patients) or by clinical follow-up (three patients). In the other 23, osteomyelitis was excluded by surgery (12 patients) or by the clinical course (11 patients). Evidence of osteomyelitis on MR consisted of abnormalities of the bone marrow with decreased signal intensity on the T1-weighted images and increased signal intensity on the T2-weighted or short-T1 inversion recovery (STIR) images. MR and bone scintigraphy were interpreted by two radiologists who were given no clinical information other than to rule out osteomyelitis. The sensitivities of MR and static bone scan were 100% for bone-marrow abnormality. Because bone-marrow abnormality in osteomyelitis associated with healing fractures was incorrectly diagnosed by MR (one case) and bone scintigraphy (two cases), the sensitivities of MR and scintigraphy for the diagnosis of osteomyelitis were 92% and 82%, respectively. The specificities of MR and scintigraphy were 96% and 65%, respectively (p less than .05). The overall accuracy for the diagnosis of osteomyelitis was 94% for MR and 71% for bone scan (p less than .05). Because of its ability to separate soft-tissue disease from underlying bone marrow, MR may be used to evaluate patients with positive bone scintigraphy to improve the specificity and accuracy of diagnosis for osteomyelitis.     

Initial experience with FSE STIR whole-body MR imaging for staging lymphoma in children

Our objective was to compare fast spin-echo (FSE) short inversion time inversion recovery (STIR) whole-body MR imaging with standard procedures in staging children with lymphoma. Eight children (age range, 2–16 years) underwent multi-station FSE STIR whole-body MR at initial staging (n=5) or for restaging following completion of therapy (n=5). Whole-body MR and conventional staging procedures, including CT (n=10), gallium-67 scintigraphy (n=9), bone scintigraphy (n=3) and bone marrow biopsy (n=7) were retrospectively compared for detection of sites involved by lymphoma and for the assigned stage. FSE STIR whole-body MR detected more sites of possible lymphomatous involvement at initial staging (87/88) and at restaging (5/5) than did conventional imaging (74/88, 3/5). MR was more sensitive than conventional imaging in detecting bone marrow involvement at initial staging. Following treatment, however, residual and therapy-induced bone marrow signal abnormalities could not be differentiated from lymphomatous involvement. Detection of nodal and visceral involvement correlated well. Our results suggest that FSE STIR whole-body MR imaging is a sensitive technique for evaluating lymphomatous involvement of bone marrow as well as non-marrow sites. Larger prospective trials are needed to determine if FSE STIR whole-body MR can replace standard radiographic procedures for initial staging and contribute in the follow-up of lymphoma in children.     

MRI findings of septic arthritis and associated osteomyelitis in adults

OBJECTIVE: The purpose of this study was to describe the soft-tissue, synovial, and osseous MRI findings of septic arthritis. MATERIALS AND METHODS: At 1.5 T (T1-weighted, T2-weighted or STIR, and contrast-enhanced images), 50 consecutive cases of septic arthritis were evaluated by two observers for synovial enhancement, perisynovial edema, joint effusion, fluid outpouching, fluid enhancement, and synovial thickening. The marrow was assessed for abnormal signal on T1- and T2-weighted images or after contrast enhancement. We noted whether the marrow signal was diffuse or abnormal in bare areas. MRI findings were compared with microbiologic, clinical, and surgical data and diagnoses. RESULTS: The frequency of MRI findings in septic joints was as follows: synovial enhancement (98%), perisynovial edema (84%), joint effusions (70%), fluid outpouching (53%), fluid enhancement (30%), and synovial thickening (22%). The marrow showed bare area changes (86%), abnormal T2 signal (84%), abnormal gadolinium enhancement (81%), and abnormal T1 signal (66%). Associated osteomyelitis more often showed T1 signal abnormalities and was diffuse. CONCLUSION: Synovial enhancement, perisynovial edema, and joint effusion had the highest correlation with the clinical diagnosis of a septic joint. However, almost a third of patients with septic arthritis lacked an effusion. Abnormal marrow signal-particularly if it was diffuse and seen on T1-weighted images-had the highest association with concomitant osteomyelitis.     

Bone marrow changes on STIR MR images of asymptomatic feet and ankles

The purpose of this study was to evaluate the prevalence, pattern and size of bone marrow changes on short-tau inversion recovery (STIR) magnetic resonance (MR) images of asymptomatic feet and ankles. In 78 asymptomatic volunteers (41 women, 37 men; median age 47 years; range 23–83 years) sagittal STIR MR images of hindfoot and midfoot were reviewed for various patterns of high signal changes in bone marrow. The size of these bone marrow changes was measured, and signal intensity was rated semi-quantitatively using a scale from 0 (=normal) to 10 (=fluid-like). Fifty percent (39/78) of all volunteers had at least one bone marrow change. Thirty-six percent (28/78) of all volunteers had edema-like changes, 26% (20/78) had necrosis-like changes, and 5% (4/78) had cyst-like changes. The long diameters of all changes varied between 4 mm and 16 mm (median 7.5 mm). The median signal intensity for all changes was 5.0 (range 1–10). Bone marrow changes on STIR MR images are commonly detected in asymptomatic feet and ankles. However, such changes tend to be small (<1 cm) or subtle.     

Glucocorticoid treatment of brain tumor patients: changes of apparent diffusion coefficient values measured by MR diffusion imaging

Glucocorticoids (GCC) generally are administered to patients with brain tumors to relieve neurological symptoms by decreasing the water content in a peritumoral zone of edema. We hypothesized that diffusion imaging and apparent diffusion coefficient (ADC) values could detect subtle changes of water content in brain tumors and in peritumoral edema after GCC therapy. The study consisted of 13 patients with intra-axial brain tumor, and ADC was measured in the tumor, within peritumoral edema, and in normal white matter remote from the tumor before and after GCC therapy. ADC also was measured in normal white matter in four control patients with no intracranial disease who were treated with GCC for other indications. Conventional MR images showed no visually evident interval change in tumor size or the extent of peritumoral edema in any subject after GCC therapy, which nonetheless resulted in a decrease in mean ADC of 7.0% in tumors (P<0.05), 1.8% in peritumoral edema (P>0.05, not significant) and 5.8% in normal white matter (P<0.05). In patients with no intracranial disease, GCC therapy decreased mean ADC in white matter by 5.4% (P<0.05). ADC measurement can demonstrate subtle changes in the brain after GCC therapy that cannot be observed by conventional MR imaging. Measurement of ADC proved to be a sensitive means of assessing the effect of GCC therapy, even in the absence of visually discernible changes in conventional MR images.     

Is there a need for contrast-enhanced T1-weighted MRI of the spine after inconspicuous short τ inversion recovery imaging?

To assess the use of contrast-enhanced T1-weighted images in comparison with short inversion recovery (STIR) images for the detection of vertebral bone marrow abnormalities. A total of 201 vertebral magnetic resonance (MR) examinations were included in a prospective trial. Examinations were performed on a 0.5-T MR scanner. The examination protocol included STIR, T2-weighted turbo spin-echo and T1-weighted spin-echo images before and after administration of gadopentetate dimeglumine. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of STIR images were calculated. In the case of abnormal STIR images the additional information from contrast-enhanced images was evaluated using Fishers exact test. The value of the combined evaluation of STIR and contrast-enhanced T1-weighted images was compared with that of the combined assessment of T2-weighted and contrast-enhanced T1-weighted images. The PPV and the NPV of STIR images for detection of vertebral bone marrow abnormalities were 99.3 and 95.9%. In the case of normal STIR images no relevant additional information was found with contrast-enhanced T1-weighted images, while in the case of abnormal STIR images significant supplementary information was obtained. There was no difference in the diagnostic value when comparing combined assessment of STIR and contrast-enhanced T1-weighted images with combined evaluation of T2-weighted and contrast-enhanced T1-weighted images. Normal STIR images allow contrast-enhanced T1-weighted images for detection of bone marrow abnormalities to be omitted, whereas further imaging is needed in case of abnormal STIR images.     

Magnetic resonance imaging of disseminated bone marrow disease in patients treated for malignancy

Magnetic resonance imaging (MRI) is a sensitive method for the diagnosis of bone marrow abnormalities, but its usefulness in detecting active disseminated cancer in this tissue in treated patients has not been determined. We therefore examined 14 children who had been treated for disseminated bone marrow involvement by neuroblastoma (n=6), lymphoma (n=3), Ewing's sarcoma (n=3), osteosarcoma (n=1), and leukemia (n= 1). MRI studies were performed at 21 marrow sites to evaluate residual or recurrent tumor and were correlated with histologic material from the same site. T₁- and T₂-weighted sequences were employed in 21 and 14 studies, respectively; short tau inversion recovery (STIR) in 18; and static gadolinium diethylene triamine pentaacetic acid (Gd-DPTA)-enhanced, T₁-weighted sequences in 13. All MRI studies showed an altered bone marrow signal. Technetium 99m methylene diphosphonate (^99mTc-MDP) bone scintigraphy was also performed (19 studies). On histologic examination, 7 marrow specimens contained tumor, and 14 did not. Of the 7 tumor-positive lesions, all T₁-weighted, 4 of 6 T₂-weighted, and all 6 STIR sequences showed abnormal signal; all 5 GdDTPA-enhanced, T₁-weighted sequences showed enhancement of the lesion. However, abnormal signals were also observed on all T₁-weighted, 6 of 8 T₂-weighted, 11 of 12 STIR, and 5 of 8 Gd-DTPA-enhanced, T₁-weighted images of the tumor-negative sites. In this clinical setting, MRI did not consistently differentiate changes associated with treatment from malignant disease.     

长骨孤立性浆细胞瘤的影像学表现

目的：探讨四肢长骨骨孤立性浆细胞瘤的影像学表现。方法：回顾性分析11例经手术或穿刺活检病理证实的四肢长骨骨孤立性浆细胞瘤的临床及影像学资料,分析其影像学征象。观察指标包括骨质破坏形态、骨皮质改变、骨膜反应、MRI信号特征、瘤周骨髓水肿、软组织改变以及MRI增强改变等。结果：11例肿瘤发生在肱骨4例,股骨7例。11例在X线片和CT上均呈溶骨性骨质破坏伴有轻度的膨胀,边界较清。10例骨皮质变薄,1例骨皮质增厚。9例可见骨皮质呈虫蚀样或锯齿状骨质破坏,未见骨膜反应。所有病例均未见瘤周骨髓水肿,且均可见软组织侵犯,3例可见明显的软组织肿块。与肌肉信号相比,10例T1WI表现为稍高信号,1例呈等信号,11例T2WI表现为高信号。MRI增强扫描,大部分病例表现为明显均匀性强化,仅1例中央可见无强化区。结论：四肢长骨骨孤立性浆细胞瘤的影像学表现具有一定的特征性,X线、CT和MRI综合评价有助于提高四肢长骨骨孤立性浆细胞瘤的诊断准确性。     

MR imaging of epicondylitis

Objective. To systematically evaluate the MR findings in patients with epicondylitis compared with asymptomatic volunteers. Design and patients. We imaged 43 elbows: 24 with epicondylitis (22 lateral, 2 medial) diagnosed by clinical examination, and 19 in 16 normal volunteers. MRI was performed at 1.5 T using axial T1-weighted, axial fat-saturated FSE, and coronal or sagittal Fast STIR sequences. Two independent observers evaluated the images for intratendon signal, tendon thickening, periosteal reaction, fluid in the radial head bursa, and anconeus edema. Results. All 24 patients with epicondylitis had increased signal on fat-saturated FSE and Fast STIR images. Twenty-two of these patients had increased intratendon T1 signal, and 19 had tendon thickening. No patient demonstrated fluid in the radial head bursa or periosteal reaction. Only two patients had subtle anconeus edema, while three patients unexpectedly had increased T2 signal within the involved epicondyle. One asymptomatic volunteer (high-performance athlete) had increased T1 and T2 signal with tendon thickening. An additional two asymptomatic volunteers had increased T1 signal only. Conclusion. MRI of epicondylitis demonstrates tendon thickening with increased T1 and T2 signal, but these findings may be seen in a small minority of asymptomatic individuals. Anconeus edema, previously demonstrated on MRI in epicondylitis, was only rarely found, and distension of the radial head bursa, surgically described, was not seen. Increased marrow T2 signal within the involved epicondyle is occasionally seen.     

Fluid-fluid levels in bone neoplasms: variation of T1-weighted signal intensity of the superior to inferior layers—diagnostic significance on magnetic resonance imaging

The diagnostic relevance of the relative T1-weighted (T1W) and T2-weighted (T2W)/short tau inversion recovery (STIR) MRI signal intensity characteristics of the superior to inferior fluid layers within fluid-fluid levels (FFLs) found in bone tumours was investigated. A retrospective analysis was performed of MRI studies of 2,568 patients presenting with a suspected bone tumour over an 8-year period. Final diagnosis was made by biopsy/surgical resection or characteristic imaging/clinical findings. Subjects were divided by the absence/presence of FFLs and benign/malignant histology. Cases with FFLs were sub-categorised by the relative signal intensity of the superior/inferior layer as high/low or low/high on T1W and T2W/STIR sequences. Out of the total of 2,568 cases, 214 (8.3%, CI 7.3–9.5%) had FFLs and 2,354 (91.7%, CI 90.5–92.7%) had no FFLs. All 214 cases with FFLs had T2W/STIR sequences available, all demonstrating high/low signal intensity characteristics; 135/214 (63.1%, CI 56.2–69.6%) were benign and 79/214 (36.9%, CI 30.4–43.8%) were malignant. Out of the 214 patients, 151 had T1W sequences performed; 52 showed high/low signal intensity, of which 30 (57.7%, CI 34.2–71.3%) were benign and 22 (42.3%, CI 28.7–56.8%) were malignant (P = 0.06 compared with no FFL group); 50 showed low/high signal intensity, of which 40 (80%, CI 66.3–90.0%) were benign and ten (20%, CI 10.0–33.7%) were malignant (P = 0.0000, compared with the no FFL group). The low/high and high/low groups had a significantly greater proportion of benign and malignant lesions, respectively (P = 0.015). In conclusion, all FFLs showed high/low signal intensity characteristics on T2W/STIR sequences. Low/high signal on T1W was significantly associated with benign disease. Malignancy may occur slightly more frequently with high/low signal on T1W.     

MR prediction of benign and malignant vertebral compression fractures

We reviewed spinal MR images of 58 patients with 98 compressed vertebrae. Benign (47 vertebrae) or malignant (51 vertebrae) etiology was established by biopsy or radiologic follow-up. Compressed vertebrae were analyzed for presence and characteristics of signal abnormality, altered vertebral contour, Schmorl's nodes, pedicular involvement, and contrast uptake. Statistical analysis was performed. Diffuse and homogeneous decrease in signal intensity on T1-weighted images, convex vertebral contour, involvement of the pedicles, and a lumbar location were more frequently observed in malignant fractures (P < .01). A thoracic location, lack of signal change, or a band-like abnormality and absence of pedicular involvement or contour abnormality characterized benign fractures (P < .01). Schmorl's nodes and enhancement did not help establish a diagnosis. When a constellation of MR criteria are applied, the accuracy of the diagnosis of malignant and benign vertebral compression fractures may reach 94%.