MR signal intensity characteristics in Legg-Calvé-Perthes disease. Value of fat-suppressed (STIR) images and contrast-enhanced T1-weighted images

PURPOSE: To evaluate the MR signal intensity characteristics in Legg-Calvé-Perthes disease on fat-suppressed (STIR) images and contrast-enhanced T1-weighted spin-echo images, and to develop criteria for the administration of contrast material. MATERIAL AND METHODS: Twenty children with Legg-Calvé-Perthes disease underwent conventional radiography and MR imaging of the hip utilizing fat-suppressed (STIR) sequences and T1-weighted spin-echo sequences before and after i.v. contrast administration. The signal intensity characteristics of the femoral head and the proximal femoral metaphysis were assessed retrospectively by two pediatric radiologists. RESULTS: Evaluation of the MR images revealed six different signal patterns within the femoral head: 1) isointense signal on all images; 2) complete signal void on all images; 3) hyperintense signal on STIR images with; or 4) without contrast enhancement on T1-weighted spin-echo images; 5) isointense signal on STIR images with; or 6) without contrast enhancement on T1-weighted images. Within the metaphysis three different signal patterns were differentiated. CONCLUSION: Combination of fat-suppressed (STIR) sequences and T1-weighted pre- and post-contrast sequences allows an accurate evaluation of Legg-Calvé-Perthes disease. In patients without signal alterations or complete signal loss on fat-suppressed and T1-weighted spin-echo images, administration of i.v. contrast is not necessary. In case of bone marrow edema on fat-supressed images, contrast-enhanced T1-weighted images are required to identify viable osseous fragments.     

放疗后脊柱MRI表现

探讨放疗后脊柱骨髓ＭＲＩ的特征。材料与方法；本组５５例脊柱放疗后患者，放疗剂量２１００－７５００ｃＧｙ，各病例开始放疗后ＭＲ检查之间的间隔时间不等，最短的是７周，最长的是２０年。结果：ＭＲＩ表现为：Ｔ１ＷＩ像椎体呈明显高信号改变，且信号均匀，与非照射野的脊柱分界清晰；Ｇ２ＷＩ像呈均匀的稍高信号；ＳＴＩＲ或Ｔ１ＷＩ抑脂成像显示椎体呈明显低信号改变。     

Bone marrow edema pattern in osteoarthritic knees: correlation between MR imaging and histologic findings

PURPOSE: To correlate magnetic resonance (MR) images of a bone marrow edema pattern with histologic findings in osteoarthritic knees. MATERIALS AND METHODS: Sixteen consecutive patients (age range, 43-79 years; mean, 67 years) referred for total knee replacement were examined with sagittal short inversion time inversion-recovery (STIR) and T1- and T2-weighted turbo spin-echo MR imaging 1-4 days before surgery. Tibial plateau abnormalities on MR images were compared quantitatively with those on histologic maps. RESULTS: The bone marrow edema pattern zone (ill-defined and hyperintense on STIR images and hypointense on T1-weighted MR images) mainly consisted of normal tissue (53% of the area was fatty marrow, 16% was intact trabeculae, and 2% was blood vessels) and a smaller proportion of several abnormalities (bone marrow necrosis [11% of area], abnormal [necrotic or remodeled] trabeculae [8%], bone marrow fibrosis [4%], bone marrow edema [4%], and bone marrow bleeding [2%]). The bone marrow edema pattern zone and the zone with a normal MR imaging appearance differed significantly in the presence of bone marrow necrosis (P =.021), bone marrow fibrosis (P =.014), and abnormal trabeculae (P =.011) but not in the prevalence of bone marrow edema (P =.069). Bone marrow edema also was found in zones with an unremarkable MR appearance (perifocal zone, 5% edema; control zone, 2% edema). CONCLUSION: A bone marrow edema pattern in osteoarthritic knees represents a number of noncharacteristic histologic abnormalities. Edema is not a major constituent of MR imaging signal intensity abnormalities in such knees.     

Diffusion-weighted MR imaging of metastatic disease of the spine: assessment of response to therapy

BACKGROUND AND PURPOSE: In cases of metastatic disease of the spine, monitoring the response to medical therapy with plain radiography, bone scanning, and conventional spin-echo sequence MR imaging is unsatisfactory because of the insensitivity or nonspecific findings of these imaging modalities. The purpose of this study was to investigate signal intensity changes of bone marrow after therapy by using diffusion-weighted MR imaging to monitor the response to medical therapy in cases of metastatic disease of the spine. METHODS: Twenty-four patients with metastatic disease of the spine were examined with MR imaging. Diffusion-weighted MR imaging and spin-echo MR imaging were performed in all patients before and after radiation therapy. Follow-up diffusion-weighted MR imaging and spin-echo MR imaging were performed for comparison purposes in nine cases at 1 month, in seven cases at 2 months, in seven cases at 3 months, and in three cases at 6 months after therapy. The diffusion-weighted MR imaging sequences were based on a steady-state free precession with a low b value (165 s/mm(2)) and a single shot stimulated echo-acquisition mode with a high b value (650 s/mm(2)). Apparent diffusion coefficient maps were obtained using two different b values incorporated in a diffusion-weighted single shot stimulated echo-acquisition mode sequence. Apparent diffusion coefficient maps were obtained in three cases. Signal intensity changes of the metastatic disease of the vertebral bone marrow before and after therapy on conventional spin-echo sequence and diffusion-weighted MR images were evaluated. RESULTS: As shown by diffusion-weighted MR imaging, metastatic disease of the vertebral bone marrow included in our study before therapy was hyperintense to normal vertebral bodies. In 23 patients with clinical improvement, metastatic disease of the spine after therapy was hypointense relative to normal vertebral bodies on the follow-up diffusion-weighted MR images. In one patient with hepatocellular carcinoma, the clinical symptoms did not improve and follow-up bone scanning performed 6 months after therapy showed increased uptake. Persistent hyperintense bone marrow after therapy was also noted on diffusion-weighted MR images. Decreased signal intensity of the metastatic disease of the spine on diffusion-weighted MR images was observed >1 month after therapy. CONCLUSION: Diffusion-weighted MR imaging shows that, with successful therapy, there is decreased signal intensity of metastatic disease of the vertebral bone marrow.     

Detection of acute avascular necrosis of the femoral head in dogs: dynamic contrast-enhanced MR imaging vs spin-echo and STIR sequences.

OBJECTIVE. Spin-echo MR imaging has been shown to be highly sensitive in the detection of avascular necrosis. Very early avascular necrosis can, however, appear normal on MR images. We compared dynamic contrast-enhanced MR imaging with conventional spin-echo and short Tl inversion-recovery (STIR) sequences for detecting acute osteonecrosis in an animal model. MATERIALS AND METHODS. Avascular necrosis was induced unilaterally in the femoral heads of five dogs that were imaged with a 1.5-T system within 3 hr of devascularization. After standard T1-weighted, T2-weighted, and STIR images, gradient-recalled echo images, 28/5 (TR/TE) with a 45 degrees flip angle, were obtained at 6-sec intervals for 90 sec synchronous with the IV administration of 0.2 mmol of gadoteridol per kilogram of body weight at a rate of 2 ml/sec via an automated injector. Two animals were reimaged after 7 days. RESULTS. Spin-echo and STIR images did not show any acute changes in the ischemic femoral heads. In contrast, significant differences were present in the enhancement profiles of the marrow spaces in the normal and ischemic femoral heads (p = .005). Normal marrow was characterized by rapid enhancement, with an average signal intensity increase of 83% peaking at 36 sec; no measurable enhancement was seen in the marrow of the ischemic femoral head. Spin-echo images, obtained 7 days after devascularization (n = 2), showed changes characteristic of avascular necrosis. Dynamic contrast-enhanced MR images showed persistent lack of enhancement in the avascular marrow of the ischemic femoral head. A junctional zone, characterized by rapid contrast enhancement in excess of 120% without early washout, was identified at the interface between normal and avascular marrow. CONCLUSION. In this experimental model, dynamic contrast-enhanced MR imaging proved significantly more sensitive than conventional spin-echo and STIR imaging in the detection of acute avascular necrosis.     

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.     

MR assessment of brain maturation: comparison of sequences.

PURPOSETo evaluate the role of short-inversion-time inversion-recovery (STIR) sequences in assessment of brain maturation.METHODSTwenty-seven infants and young children with normal neurologic development were examined by 1.5-T MR using a circularly polarized head coil. Axial T1-weighted and T2-weighted and spin-echo and STIR images were obtained. Signal intensity of different anatomic structures at individual sequences was classified relatively to reference sites and temporal sequence of signal intensity was observed.RESULTSSignal intensity changes on T1-weighted and T2-weighted spin-echo sequences occurred at ages described in various previous publications. On STIR images intensity changes became apparent at a time between T1-weighted and T2-weighted images. The advantages of the STIR sequence were improved assessment of myelination of subcortical cerebral white matter from 6 to 14 months and good contrast between white matter lesions and cerebrospinal fluid.CONCLUSIONOur results suggest that from 0 to 6 months myelination can be assessed best using a combination of T1-weighted and T2-weighted images; from 6 to 14 months a combination of T2-weighted and STIR images seems to be advantageous; after 14 months the use of only T2-weighted sequences is sufficient. After 14 months STIR images may be useful in detecting small periventricular white matter lesions or in cases with retarded myelination and isointensity between gray matter and white matter.     

Low-field-strength MR imaging of failed hip arthroplasty: association of femoral periprosthetic signal intensity with radiographic, surgical, and pathologic findings

PURPOSE: To investigate the association between periprosthetic signal intensity at low-field-strength magnetic resonance (MR) imaging after failed hip arthroplasty and radiographic, surgical, and pathologic findings. MATERIALS AND METHODS: The study group comprised 22 consecutive women who underwent hip arthroplasty (mean age, 62 years; age range, 35-74 years). All patients underwent MR imaging prior to revision surgery. Coronal fast short inversion time inversion-recovery (STIR) images and spin-echo T1-weighted images were obtained with a 0.5-T MR imaging unit before and after administration of contrast material. The periprosthetic region was divided into the seven femoral Gruen zones. Two observers retrospectively analyzed signal intensity patterns. Association of signal intensity patterns with radiographic, surgical, and pathologic findings was determined with chi2 analysis and generalized estimating equations. RESULTS: Diagnostic-quality images were obtained for 150 zones. Periprosthetic signal intensity was greater than that of bone marrow in the distal femur on the fast STIR images, and no contrast enhancement was seen on the T1-weighted images (type I signal intensity pattern) in 11 zones. Signal intensity was greater than that of bone marrow on the fast STIR images, and contrast enhancement was seen on the T1-weighted images (type II signal intensity pattern) in 45 zones. Signal intensity was less than or equal to that of bone marrow on the fast STIR images, and no contrast enhancement was seen on the T1-weighted images (type III signal intensity pattern) in 94 zones. Type I and II patterns were associated with focal or nonfocal lucency, an unstable stem, and fibrosis or granuloma. A type III pattern was associated with a normal radiographic appearance, a stable stem, and normal bone tissue. Significant association was demonstrated between periprosthetic signal intensity and radiographic (P <.001, chi2 test and generalized estimating equations), surgical (P <.05, Mantel-Haenszel chi2 test and generalized estimating equations), and pathologic findings (P <.05, chi2 test). CONCLUSION: Low-field-strength MR imaging depicted periprosthetic tissue signal intensity that was significantly associated with radiographic, surgical, and pathologic findings.     

Magnetic resonance investigation of bone marrow following priming and stem cell mobilization

PURPOSE: To evaluate application of MRI and magnetic resonance spectroscopy (MRS) to monitor bone marrow cellularity during pretransplant priming with chemotherapy and hematopoietic growth factor (HGF) administration. MATERIALS AND METHODS: A total of 10 lymphoma and myeloma patients, in remission following induction therapy and considered eligible for high-dose therapy and autologous stem cell transplantation, were included in the study. MR investigation was scheduled four times: at study entry, and one, two, and four weeks following priming. Priming with cyclophosphamide and recombinant human granulocyte colony-stimulating factor (rhG-CSF) started the day after study entry. MR parameters studied in a region of interest were as follows: bone marrow intensity on short-time inversion-recovery (STIR) turbo spin-echo (TSE; thus STIRTSE) and on T1-weighted TSE (T1TSE) images, T2 value for fat component, T2 value for water component, water/fat ratio (W/F), T1 value for fat component, and T1 value for water component. RESULTS: The results did not support the hypothesis that hematopoietic expansion quantitated and monitored by MR correlates to the level of mobilized progenitor cells. CONCLUSION: The results indicate that release of stem cells is a more complex phenomenon than hematopoietic expansion and reduction of fat tissue in bone marrow.     

宫颈癌放疗后盆腔正常组织的早期M RI变化

目的：分析宫颈癌放射治疗后盆腔正常组织器官的磁共振成像（MRI）变化。方法18例经病理确诊的宫颈癌患者在放疗前、后不同时间段接受盆腔MRI检查。在M RI观察盆腔软组织、器官在放疗前后的形态及信号变化。结果放疗后盆腔内多出现软组织、器官的异常MRI表现,其中直肠异常表现发生率最高（8/18,占44％）,表现为肠壁增厚T2 WI呈高或等信号,STIR呈高信号。结论磁共振成像可显示放射治疗所致的盆腔内组织器官的损伤情况。     

Repopulation of marrow after transplantation: MR imaging with pathologic correlation

Sixty-seven magnetic resonance (MR) studies of the lumbar spine were performed in 15 patients with bone marrow transplants, and the appearance of marrow regeneration on MR images was correlated with results of bone marrow biopsy and pathologic examination. After transplantation, T1-weighted MR images of vertebral marrow showed a characteristic band pattern consisting of a peripheral zone of intermediate signal intensity and a central zone of bright signal intensity. Reciprocal changes were identified on short inversion time inversion recovery images. At histologic examination the central zone corresponded to fatty marrow; the peripheral zone corresponded to a zone of regenerating hematopoietic cells. Posttransplantation T1 and T2 relaxation times of the entire vertebral marrow were calculated from the spin-echo images; no statistically significant trends in relaxation times were noted. Knowledge of the normal MR pattern of marrow regeneration after transplantation may be useful in screening for residual marrow disease, determining marrow engraftment, and differentiating marrow repopulation with normal versus malignant cells.     

MR features of tuberculous osteomyelitis

OBJECTIVE: To describe the MR imaging features of tuberculous osteomyelitis. DESIGN AND PATIENTS: MR imaging features of 11 patients (14-65 years) with proven extra-spinal tuberculous osteomyelitis were reviewed. Osseous and adjacent soft-tissue changes were analyzed. RESULTS: On the basis of the signal intensity characteristics compared with the normal marrow fat, two kinds of lesions were observed: (a) predominantly intermediate to low signal intensity lesions on T2-weighted images with low signal intensity on T1-weighted images, and (b) lesions which had a discrete peripheral zone of marginally higher signal intensity than the center on T1-weighted images and surrounding edema and lower signal intensity than the fatty bone marrow with variable signal intensity on T2-weighted images. Soft-tissue abscesses and marrow edema were each noted in eight cases. Soft-tissue edema was noted in most cases. CONCLUSION: An osseous lesion with intermediate to low signal intensity on T2-weighted images and associated soft-tissue abscess may be suggestive of tuberculous osteomyelitis. Lesions with a rim of mildly increased signal intensity on T1-weighted images, a non-specific indicator of an infective process, may also be seen.     

Musculoskeletal neoplasms after intraarterial chemotherapy: correlation of MR images with pathologic specimens

The most accurate prognostic indicator in patients with musculoskeletal sarcomas is the percentage of tumor necrosis after intraarterial chemotherapy. Magnetic resonance (MR) imaging was evaluated to determine its ability to indicate the percentage of necrosis in musculoskeletal neoplasms after treatment. Fourteen patients with musculoskeletal neoplasms underwent treatment protocols including intraarterial chemotherapy (n = 14), radiation therapy (n = 6), and systemic chemotherapy (n = 14). All patients underwent MR imaging before and after treatment, and all underwent either limb salvage surgery (n = 8) or amputation (n = 6) within 1 week of the last MR examination. Standard unehanced spin-echo T1-, spin-density-, and T2-weighted MR sequences were used. The MR images were compared with the pathologic specimens. On T2-weighted images, the signal intensities of viable tumor, tumor necrosis, edema, hemorrhage, and necrosis overlapped. With the unenhanced spin-echo technique, MR imaging cannot be used to predict the percentage of tumor necrosis in musculoskeletal neoplasms after intraarterial chemotherapy.     

STIR MR imaging of the orbit

Fifteen patients with CT-documented orbital lesions were evaluated with MR imaging at 1.5 T with both conventional spin-echo (SE) and short inversion time inversion recovery (STIR) sequences. Fat signal was reliably nulled at inversion times of approximately 120-200 msec in all cases, thereby allowing clear detection of all retrobulbar lesions and normal structures on STIR images as markedly hyperintense relative to fat. All lesions were also clearly depicted on SE images; in fact, short repetition time/short echo time SE sequences were at least as useful as STIR images for illustrating anatomic structures and mass lesions, and in a much shorter scanning time. Separation of optic nerve from perioptic subarachnoid space was clear on SE images, but often difficult or impossible on STIR images owing to the relatively high intensity of normal optic nerves on STIR images. The synergism of relaxation prolongation with STIR actually resulted in loss of information, as any ability to separate the effects of T1 from T2 on signal intensity was impossible when STIR was the sole pulse sequence. We believe that more information is obtained with standard SE sequences than with STIR sequences, and therefore SE remains the method of choice for orbital MR imaging.     

STIR MR Imaging of the Orbit

Fifteen patients with CT-documented orbital lesions were evaluated with MR imaging at 1.5 T with both conventional spin-echo (SE) and short inversion time inversion recovery (STIR) sequences. Fat signal was reliably nulled at inversion times of approximately 120–200 msec in all cases, thereby allowing clear detection of all retrobulbar lesions and normal structures on STIR images as markedly hyperintense relative to fat. All lesions were also clearly depicted on SE images; in fact, short repetition time/short echo time SE sequences were at least as useful as STIR images for illustrating anatomic structures and mass lesions, and in a much shorter scanning time. Separation of optic nerve from perioptic subarachnoid space was clear on SE images, but often difficult or impossible on STIR images owing to the relatively high intensity of normal optic nerves on STIR images. The synergism of relaxation prolongation with STIR actually resulted in loss of information, as any ability to separate the effects of T1 from T2 on signal intensity was impossible when STIR was the sole pulse sequence.We believe that more information is obtained with standard SE sequences than with STIR sequences, and therefore SE remains the method of choice for orbital MR imaging.     

活体骨髓激发的MRI研究

目的探讨激发后骨髓的MRI变化情况。方法给经治疗缓解的11名淋巴瘤或多发性骨髓瘤成人患者注射rhG-CSF,然后分别于rhG-CSF注射前(0周)和注射后1周、2周、4周使用T1WI和STIR脂肪抑制观察患者L3椎体和髂骨骨髓的MRI和对比信噪比(CNR)。3位有经验的放射科医生分别阅片,取其平均结果。同时计算骨髓和皮下脂肪的CNR比值,并进行配对检验。结果与rhG-CSF激发前对比,激发后1周所有患者的骨髓MRI均未见明显改变,激发后2周有5例患者的骨髓MRI信号轻度升高,激发后4周所有患者的骨髓MRI信号均明显降低。激发后1、2、4周所有患者的骨髓CNR改变与激发前对比,均没有统计学差异。腰椎和髂骨骨髓的改变除1例在2周和1例在4周时骨髓改变不一致外,其余病例2个部位骨髓的改变一致。结论被rhG-CSF激发4周后,骨髓MRI信号明显减低。但骨髓CNR的改变没有统计学意义。     

Magnetic resonance imaging of bone marrow changes in Gaucher disease during enzyme replacement therapy: first German long-term results

Objective: . Since 1991, enzyme replacement therapy (ERT) has been available for patients with Gaucher disease in Germany. The aim of this study was to analyse the MR pattern of bone marrow involvement and response to ERT in Gaucher disease type I. Patients and design: . Thirty patients with Gaucher disease type I had MRI examinations prior to initiation of ERT with alglucerase/imiglucerase and during follow-up. Median MR follow-up and duration of ERT were 36 months. Coronal T1- and T2-weighted spin-echo images of the lower extremities were obtained to evaluate changes in the appearance of yellow marrow. MR images were categorized as having either a homogeneous (type A) or non-homogeneous patchy (type B) appearance of bone involvement and response to ERT was assessed by two radiologists. Results: . Overall, 19 of 30 patients (63%) showed an increased signal intensity on T1- and T2-weighted images after 36 months of ERT, consistent with partial reconversion of fatty marrow during treatment. Focal bone lesions surrounded by a low signal intensity (SI) rim did not respond to ERT, suggesting bone infarcts. Of the 11 patients with bone infarcts (low SI rim lesion), 82% had the non-homogeneous type B pattern (P=0.0021). In 86% of patients with splenectomy, bone infarcts were seen (P<0.05). Conclusions: . MRI using T1- and T2-weighted spin-echo sequences is a valuable, non-invasive method for monitoring bone marrow response in patients receiving ERT. A non- homogeneous patchy signal intensity of bone marrow involvement correlates with the presence of bone infarcts (P=0.0021). Received: 27 July 2000 Revision requested: 26 October 2000 Revision received: 9 March 2001 Accepted: 12 March 2001     

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.     

The plantar fasciotomy: MR imaging findings in asymptomatic volunteers

Objective. To determine the postoperative appearance of the plantar fascia on MR imaging after a fasciotomy has been performed, and to compare the postsurgical appearance of the fascia after an open and endoscopic procedure.<@head-abs-p1.lf>Design and patients. Fifteen asymptomatic volunteers (12 women, 3 men; age range 22–49 years, mean age 33 years) with prior fasciotomies for treatment of longstanding plantar fasciitis were studied. Fourteen volunteers had a unilateral release and one volunteer had bilateral releases, allowing for assessment of 16 ankles. Eight fasciotomies were performed through an open incision and eight were performed endoscopically. The average time between surgery and imaging was 24 months (range 11–46 months). The site of surgery was established from the operative reports. Proton density (PD)-weighted and T2-weighted images in three orthogonal planes were obtained on a 1.5-T magnet. In eight studies, T1-weighted sagittal and STIR sagittal images were included. The fascia in each ankle was assessed for morphology and signal intensity. Perifascial soft tissues and bone marrow were assessed for edema. Preoperative MR studies were available in five volunteers.<@head-abs-p1.lf>Results. There was no apparent difference in the postoperative appearance of the ankle after an open or endoscopic procedure except for scar formation in the subcutaneous fat which was common after an open procedure (P<0.05). Three ankles had a gap in the fascia (one open, two endoscopic). The plantar fascia measured a mean of 7.0 mm (range 5–10 mm) at the fasciotomy, and 8.3 mm (range 6–12 mm) at the enthesis. At the fasciotomy, 11 of 13 ankles had an indistinct deep contour and 9 of 13 had an indistinct superficial contour. At the enthesis, 13 of 16 ankles had an indistinct deep contour and 6 of 16 had an indistinct superficial contour. Compared with preoperative MR studies there was an average reduction in the fascial thickness at the enthesis of 14% (range 9–20%), but the thickness at the fasciotomy nearly doubled. No edema was evident in the fascia, perifascial tissues, deep plantar muscles, or calcaneal bone marrow.<@head-abs-p1.lf>Conclusions. The average thickness of the plantar fascia in asymptomatic volunteers after surgery is nearly 2–3 times that of normal. While there is increased thickness at the site of surgery, the changes in morphology and signal intensity were most prominent at the enthesis. The key observation was absence of edema in the fascia and perifascial soft tissues. This baseline information may be of value when assessing MR studies of symptomatic patients. Received: 23 March 1999 Revision requested: 19 May 1999 Revision received: 4 June 1999 Accepted: 9 June 1999     

MR appearance of radiation hepatitis.

The histopathologic changes of radiation hepatitis have been well described. The magnetic resonance (MR) appearance, however, has been described only in two case reports. We obtained serial MR scans of patients undergoing therapeutic irradiation for Hodgkins lymphoma to determine the time course of changes in signal intensity of the liver. We found an increased signal intensity of the irradiated portion of the liver on T2-weighted images. Changes first detected at 4 weeks following 3600 cGy to the abdomen returned to normal signal intensity within 60 days following completion of radiation therapy. One patient demonstrated a subtle increase in signal intensity of the irradiated region as early as 7 days after receiving 2000 cGy. Our results suggest that MR imaging is a useful noninvasive means of tracing the course of radiation hepatitis.