Determining the factors influencing the symptoms related to naviculo-medial cuneiform coalition.

PURPOSE: We aimed to determine the factors that influence the symptoms of naviculo-cuneiform (NC) coalition using radiography and computed tomography (CT). METHODS: We retrospectively reviewed the radiographic and CT findings of 37 NC coalition cases. The existence of a large pit (depth >3 mm), irregular articular surface, joint space narrowing, dorsal bony spur, subchondral sclerosis, multiple subchondral bony cysts, and intra-articular loose body were evaluated on radiographs or CT. The size of the largest subchondral bony cyst was also measured using CT. All cases were divided into two subgroups according to the symptoms. Fisher's exact test was used to distinguish the factors influencing the symptoms. RESULTS: Twenty-three and fourteen feet were enrolled into the symptomatic and asymptomatic groups, respectively. The rates of the large pit on either radiograph (47.83 vs. 21.43%) or CT (65.22 vs. 28.57%) were significantly different between both groups ( p = 0.001). The mean size of the largest subchondral bony cyst on CT was also significantly greater in the symptomatic group (4.25 vs. 1.53 mm, p = 0.005). CONCLUSION: A large deep pit and huge subchondral bony cyst on the radiograph or CT can be related to symptoms for the patient with NC coalition. A CT is highly recommended for a more accurate evaluation in patients with NC coalition.

Breast-specific gamma imaging of invasive breast cancer: Clinicopathologic factors affecting detectability and correlation with mammographic findings.

PURPOSE: To investigate the factors affecting detectability of invasive breast cancers on BSGI. MATERIAL AND METHODS: We evaluated BSGI, mammography and pathologic reports of 89 patients with invasive breast cancers. RESULTS: 87.6% were visible on BSGI. Cancer in old or postmenopausal women were more visible on BSGI (p = 0.003, 0.046). Cancers ≥ 1.0 cm in size were significantly more visible on BSGI than those <1 cm in size (p = 0.002). Cancers in fatty breasts were more visible than those in dense breasts (p = 0.042). CONCLUSION: Invasive cancers in older, postmenopausal patients, cancers with size ≥1.0 cm, and those with fatty breast are better visualized by BSGI, than those in younger, premenopausal patients, with size <1.0 cm and dense breast.

Beta-amyloid imaging in dementia.

Alzheimer's disease (AD) is a neurodegenerative disorder associated with extracellular plaques, composed of amyloid-beta (Aß), in the brain. Although the precise mechanism underlying the neurotoxicity of Aß has not been established, Aß accumulation is the primary event in a cascade of events that lead to neurofibrillary degeneration and dementia. In particular, the Aß burden, as assessed by neuroimaging, has proved to be an excellent predictive biomarker. Positron emission tomography, using ligands such as 11C-labeled Pittsburgh Compound B or 18F-labeled tracers, such as 18F-florbetaben, 18F-florbetapir, and 18F-flutemetamol, which bind to Aß deposits in the brain, has been a valuable technique for visualizing and quantifying the deposition of Aß throughout the brain in living subjects. Aß imaging has very high sensitivity for detecting AD pathology. In addition, it can predict the progression from mild cognitive impairment to AD, and contribute to the development of disease-specific therapies.

Quantitative assessment of simultaneous F-18 FDG PET/MRI in patients with various types of hepatic tumors: Correlation between glucose metabolism and apparent diffusion coefficient.

PURPOSE: Metabolism and water diffusion may have a relationship or an effect on each other in the same tumor. Knowledge of their relationship could expand the understanding of tumor biology and serve the field of oncologic imaging. This study aimed to evaluate the relationship between metabolism and water diffusivity in hepatic tumors using a simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) system with F-18 fluorodeoxyglucose (FDG) and to reveal the metabolic and diffusional characteristics of each type of hepatic tumor. METHODS: Forty-one patients (mean age 63 ± 13 years, 31 male) with hepatic tumors (18 hepatocellular carcinoma [HCC], six cholangiocarcinoma [CCC], 10 metastatic tumors, one neuroendocrine malignancy, and six benign lesions) underwent FDG PET/MRI before treatment. Maximum standard uptake (SUVmax) values from FDG PET and the apparent diffusion coefficient (ADC) from the diffusion-weighted images were obtained for the tumor and their relationships were examined. We also investigated the difference in SUVmax and ADC for each type of tumor. RESULTS: SUVmax showed a negative correlation with ADC (r = -0.404, p = 0.009). The median of SUVmax was 3.22 in HCC, 6.99 in CCC, 6.30 in metastatic tumors, and 1.82 in benign lesions. The median of ADC was 1.039 × 10-3 mm/s2 in HCC, 1.148 × 10-3 mm/s2 in CCC, 0.876 × 10-3 mm/s2 in metastatic tumors, and 1.323 × 10-3 mm/s2 in benign lesions. SUVmax was higher in metastatic tumors than in benign lesions (p = 0.023). Metastatic tumors had a lower ADC than CCC (p = 0.039) and benign lesions (p = 0.004). HCC had a lower ADC than benign lesions, with a suggestive trend (p = 0.06). CONCLUSION: Our results indicate that SUVmax is negatively correlated with ADC in hepatic tumors, and each group of tumors has different metabolic and water diffusivity characteristics. Evaluation of hepatic tumors by PET/MRI could be helpful in understanding tumor characteristics.

Prognostic value of preoperative 18F-FDG PET/CT in papillary thyroid cancer patients with a high metastatic lymph node ratio: a multicenter retrospective cohort study.

OBJECTIVE: Metastatic lymph node ratio (MLNR) is a known significant predictor of disease-free survival in differentiated thyroid cancer. The authors investigated the ability of preoperative fluorine-18 fluorodeoxyglucose (F-FDG) PET/CT to predict recurrence after surgery with radioactive iodine therapy considering MLNR. PATIENTS AND METHODS: A total of 274 patients who underwent preoperative PET/CT and surgery with radioactive iodine therapy were enrolled. The tumor-to-liver uptake ratio on PET/CT was calculated by dividing the maximum standardized uptake value of a primary lesion by the mean standardized uptake value of the normal liver. High F-FDG uptake was defined as tumor-to-liver uptake ratio more than the median cutoff value (2.1). MLNR was calculated by dividing the number of metastatic lymph nodes (LNs) by the number of cervical LNs removed. A high MLNR was also defined as one more than a threshold value (0.4), identified by plotting Kaplan-Meier survival curves and comparing them using the log-rank test. The prognostic significances of clinicopathologic variables were analyzed. RESULTS: Fifteen (5.5%) patients developed recurrence in the thyroid bed or in cervical LNs. Cox regression analysis showed that a high MLNR was significantly associated with a worse disease-free survival (odds ratio 6.95; 95% confidence interval: 2.36-20.47; P<0.001). A subgroup analysis of 70 patients with a high MLNR showed that only high F-FDG uptake was significantly associated with a worse disease-free survival (odds ratio 5.77; 95% confidence interval: 1.22-27.16; P=0.027). CONCLUSION: High F-FDG uptake of primary lesion on preoperative PET/CT has selective prognostic value according to the extent of metastatic LNs (MLNR>0.4).

Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Findings of Post Traumatic Lymphangioma in a Young Adult Male.

The authors report the case of a 34-year-old male, who underwent a fluorine-18 fluoro deoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scan 7 years after trauma for the evaluation of multifocal masses in the right iliac and right inguinal areas. CT findings showed multifocal low density masses and 18F-FDG PET revealed slightly increased uptake (maximum standardized uptake value [SUVmax] 3.1). These findings did not exclude the possibility of a benign or malignant lesion. To achieve differential diagnosis, partial surgical excision was performed and a pathologic examination subsequently revealed lymphangioma. Here, the authors describe the 18F-FDG PET/CT findings of a rare case of lymphangioma resulting from trauma.

Correlation Between Apparent Diffusion Coefficients and Standardized Uptake Values in Hybrid (18)F-FDG PET/MR: Preliminary Results in Rectal Cancer.

PURPOSE: Fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWI) share the same role in clinical oncology and it is feasible to obtain the standardized uptake value (SUV) and apparent diffusion coefficient (ADC) simultaneously by emerging the hybrid positron emission tomography/magnetic resonance (PET/MR). This study investigated the correlation between the ADCs of rectal cancer lesions and their SUVs derived from hybrid PET/MR. METHODS: Nine patients with histologically proven rectal adenocarcinoma (5 men, 4 women; mean age, 70 ± 15.91 years) underwent torso (18)F-FDG PET/CT and regional hybrid (18)F-FDG PET/MR sequentially. A fixed threshold value of 40 % of maximum uptake was used to determine tumor volume of interest (VOI) on PET image; SUVmax, SUVpeak, and SUVmean were calculated automatically. A single freehand region of interest (ROI) was drawn on high b-value (b1000) DWI image and copied to corresponding ADC map to determine the ADCmean of rectal cancer lesion. Spearman's rank correlation coefficient (ρ) was calculated to determine the correlation between SUVs and ADC values. RESULTS: SUVmax, SUVpeak, and SUVmean derived by hybrid PET/MR were 12.35 ± 4.66 (mean ± standard deviation), 9.66 ± 3.15 and 7.41 ± 2.54, respectively. The ADCmean value of rectal cancer lesions was 1.02 ± 0.08 × 10(-3)mm(2)/s. ADCmean was significantly and inversely correlated with SUV values (SUVmax, ρ = -0.95, p < 0.001; SUVpeak, ρ = -0.93, p < 0.001; SUVmean, ρ = -0.91, p = 0.001). CONCLUSIONS: This preliminary hybrid PET/MR study demonstrates a significant inverse correlation exists between metabolic activity on (18)F-FDG PET and water diffusion on DWI in rectal cancer.

A new screening method for multidirectional shoulder instability on magnetic resonance arthrography: labro-capsular distance.

OBJECTIVE: To compare the capsular dimension as measured on magnetic resonance arthrography (MRA) between patients with multidirectional instability (MDI) of the shoulder and control subjects without instability. Ultimately, we aimed to develop an easy and reliable new screening method to assess MDI of the shoulder using MRA. MATERIALS AND METHODS: MRA images of patients with MDI of the shoulder (n = 25) during a 6-year period (February 2010 to May 2015) were retrospectively reviewed. A control group (n = 26) without instability was also identified. The capsular area was measured using a new screening method we termed labro-capsular (LC) distance. MRA images of the two groups were randomly mixed, and two orthopedic surgeon reviewers recorded anterior, posterior, and inferior LC distance measurements on axial and coronal images using a mid-glenoid cut. RESULTS: The inferior LC distance increased significantly in the patient group versus control group (P < 0.001), but there were no statistically significant differences in the anterior (P = 0.1165) and posterior (P = 0.5229) LC distances. An inferior LC distance >16.88 mm is most suggestive of MDI of the shoulder because of its high sensitivity (76 %) and specificity (96 %). CONCLUSION: The inferior LC distance can be easily and quickly measured and used as an effective clinical screening method for atraumatic MDI of the shoulder.

Late Onset Osteonecrosis of the Proximal Phalanx of the Great Toe in a Child.

Osteonecrosis, also known as avascular necrosis or osteochondrosis, refers to the death of bone tissue resulting from a to lack of blood supply. Osteonecrosis of the foot is most commonly seen in the talus and metatarsals and not as frequently in other bones. We report an extremely rare case of late-onset osteonecrosis of the proximal phalangeal head of the great toe in a 9-year-old male. Plain radiographs and computed tomography did not show any findings of osteonecrosis initially. However, because of persistent pain at the interphalangeal joint of the first toe and a decrease in the range of movement at the interphalangeal joint at 7 months after injury, the patient underwent additional examination with repeated radiographs and magnetic resonance imaging. We diagnosed late-onset osteonecrosis as a result of a subtle traumatic type I dislocation. Conservative treatment led to spontaneous recovery, leaving a bony fragment in the interphalangeal joint. To our knowledge, this is the first report of late-onset proximal phalangeal osteonecrosis after trauma in the great toe.

Case Reports on the Differentiation of Malignant and Benign Intratracheal Lesions by 18F-FDG PET/CT.

Malignant tracheal tumors (primary and secondary) are rare and benign tumors of the tracheobronchial tree are also rare. Few reports have been issued on the F-fluorodeoxyglucose (F-FDG) positron emission tomography (PET) findings of tracheal tumors or benign nontumorous tracheal lesions, which have been mainly studied by computed tomography (CT). The author reports 2 cases of intratracheal lesions with quite different F-FDG PET/CT findings. The first case was of a 73-year-old woman with colon cancer treated by hemicolectomy and subsequent adjuvant chemotherapy. Follow-up F-FDG PET/CT after 6 years revealed a hypermetabolic fungating mass (SUVmax: 5.8) in the distal trachea and biopsy confirmed intratracheal metastasis. The second case involved a 61-year-old man with tongue cancer who underwent mouth floor mass excision and right supraomohyoid neck dissection with submental flap reconstruction. Tracheal lesion was incidentally found during a F-FDG PET/CT follow-up study conducted 1 year later. A benign intratracheal condition with low FDG uptake (SUVmax: 1.2) and the lesion was not visualized by neck CT 4 months later. F-FDG PET/CT uptake was helpful in differentiating benign and malignant intratracheal lesions.

An Incidental Finding of Skull Hemangioma During 18F-FP CIT Brain PET/CT.

F-FP CIT has been well established and used for the differential diagnosis of atypical parkinsonian disorders, including idiopathic Parkinson disease. A 54-year-old woman with a history of left hand and leg tremor underwent F-FP CIT PET/CT for the differentiation of parkinsonism. The F-FP CIT PET/CT incidentally showed focal dopamine transporter uptake in the right frontal bone. Brain MRI scan showed heterogeneous high signal intensity with enhancement in right frontal bone diploic space without cortical disruption, suggestive of cavernous hemangioma. Besides the nigrostriatal dopaminergic system, F-FP CIT PET/CT showed a skull tumor.

Enchondroma of the Foot.

The present study is a review of 20 patients with enchondroma of the foot treated from January 2005 to March 2012. All patients were examined clinically, followed by an evaluation of their enchondroma of the foot radiographically and an assessment of the outcome of their surgical intervention. The patients' sex and age, enchondroma location, findings from imaging studies such as plain radiography, computed tomography, and magnetic resonance imaging, clinical findings, operative findings, and treatment outcomes were recorded. The average postoperative follow-up period was 24 months. Eighty percent of the tumors were located in the proximal phalanx and 14 (70%) patients presented with pathologic fracture. The plain radiographs and computed tomography findings revealed 13 (65%) cases of internal calcification and 11 (55%) with endosteal scalloping. A periosteal reaction was seen only in 4 (20%) cases. Magnetic resonance imaging of 11 (55%) patients showed low T1-weighted and high T2-weighted signal intensity in all cases. Internal septa and nodules with low T2-weighted signal intensity were observed in 9 (82%) out of 11 cases, and adjacent soft tissue edema was noted in 9 (82%). All patients underwent curettage of the tumor and bone grafting as their surgical treatment. No recurrence or postoperative complications were observed during the 24-month follow-up period. Enchondroma of the foot most frequently involves the proximal phalangeal bone and is often associated with pathologic fracture. The unique clinical signs and characteristic radiographic images are easily recognized, making this a relatively easy diagnosis. With appropriate treatment, a good surgical outcome can be expected.

Postoperative ultrasonography of the musculoskeletal system.

Ultrasonography of the postoperative musculoskeletal system plays an important role in the accurate diagnosis of abnormal lesions in the bone and soft tissues. Ultrasonography is a fast and reliable method with no harmful irradiation for the evaluation of postoperative musculoskeletal complications. In particular, it is not affected by the excessive metal artifacts that appear on computed tomography or magnetic resonance imaging. Another benefit of ultrasonography is its capability to dynamically assess the pathologic movement in joints, muscles, or tendons. This article discusses the frequent applications of musculoskeletal ultrasonography in various postoperative situations including those involving the soft tissues around the metal hardware, arthroplasty, postoperative tendons, recurrent soft tissue tumors, bone unions, and amputation surgery.

Initial experience of integrated PET/MR mammography in patients with invasive ductal carcinoma.

The purpose of this study was to evaluate the feasibility of integrated fluorine-18-fluorodeoxyglucose positron emission tomography/magnetic resonance ((18)F-FDG PET/MR) mammography in invasive ductal carcinoma (IDC) patients. From August 2012 to March 2013, we enrolled 42 consecutive breast cancer patients who received whole- body PET/MR and subsequent PET/MR mammography by an integrated PET/MR scanner and were scheduled for surgery within 2 weeks after the of scan. On the whole body PET/MR, 2-point Dixon VIBE, coronal T1w image, axial T2w image, and post-contrast T1 sequences were acquired with simultaneous PET acquisition. For PET/MR mammography, T1w, T2w, and dynamic contrast-enhancement (DCE) sequences were acquired using a breast coil during simultaneous PET acquisition. We compared the detectability of the lesions between whole-body PET/MR and PET/MR mammography. Forty-eight IDC (1.89±1.19cm of width) were diagnosed in 42 women. Lesion conspicuity in (18)F-FDG PET was equivalent between whole-body PET/MR and PET/MR mammography; both PET/MR images showed 38 hypermetabolic masses. In the analysis of 10 IDC with <1.0cm wide lesions, only 1 IDC showed (18)F-FDG uptake, and 4 IDC were noted on whole-body PET/MR; however, all 10 IDC showed a depictable mass on PET/MR mammography. In the analysis of 38 IDC >1.0cm wide, 37 IDC showed (18)F-FDG uptake, and 38 IDC were detected on both whole-body PET/MR and PET/MR mammography. The overall sensitivity was 79.2% (38/48) on PET, 87.5% (42/48) on whole-body PET/MR, and 100% on PET/MR mammography. The SUV between whole-body PET/MR and PET/MR mammography showed strong and highly significant correlation (r=0.987, P<0.001). In conclusion, our results, although in a limited number of cases show that integrated PET/MR mammography is feasible and has the advantage of combining high-resolution breast images with metabolic images. Furthermore, PET/MR mammography could provide an accurate diagnosis in case of IDC that are less than 1cm in size.

Evaluation of Dixon Sequence on Hybrid PET/MR Compared with Contrast-Enhanced PET/CT for PET-Positive Lesions.

PURPOSE: Hybrid positron emission tomography and magnetic resonance (PET/MR) imaging performs a two-point Dixon MR sequence for attenuation correction. However, MR data in hybrid PET/MR should provide anatomic and morphologic information as well as an attenuation map. We evaluated the Dixon sequence of hybrid PET/MR for anatomic correlation of PET-positive lesions compared with contrast-enhanced PET/computed tomography (CT) in patients with oncologic diseases. METHODS: Twelve patients underwent a single injection, dual imaging protocol. PET/CT was performed with an intravenous contrast agent (85 ± 13 min after (18)F-FDG injection of 403 ± 45 MBq) and then (125 ± 19 min after injection) PET/MR was performed. Attenuation correction and anatomic allocation of PET were performed using contrast-enhanced CT for PET/CT and Dixon MR sequence for hybrid PET/MR. The Dixon MR sequence and contrast-enhanced CT were compared for anatomic correlation of PET-positive lesions (scoring scale ranging from 0 to 3 for visual ratings). Additionally, standardized uptake values (SUVs) for the detected lesions were assessed for quantitative comparison. RESULTS: Both hybrid PET/MR and contrast-enhanced PET/CT identified 55 lesions with increased FDG uptake in ten patients. In total, 28 lymph nodes, 11 bone lesions, 3 dermal nodules, 3 pleural thickening lesions, 2 thyroid nodules, 1 pancreas, 1 liver, 1 ovary, 1 uterus, 1 breast, 1 soft tissue and 2 lung lesions were present. The best performance was observed for anatomic correlation of PET findings by the contrast-enhanced CT scans (contrast-enhanced CT, 2.64 ± 0.70; in-phase, 1.29 ± 1.01; opposed-phase, 1.29 ± 1.15; water-weighted, 1.71 ± 1.07; fat weighted, 0.56 ± 1.03). A significant difference was observed between the scores obtained from the contrast-enhanced CT and all four coregistered Dixon MR images. Quantitative evaluation revealed a high correlation between the SUVs measured with hybrid PET/MR (SUVmean, 2.63 ± 1.62; SUVmax, 4.30 ± 2.88) and contrast-enhanced PET/CT (SUVmean, 3.88 ± 2.30; SUVmax, 6.53 ± 4.04) in PET-positive lesions (SUVmean, ρ = 0.93; SUVmax, ρ = 0.95), although hybrid PET/MR presented a decrease of SUVs compared with contrast-enhanced PET/CT (mean reduction; SUVmean, 32.44 ± 15.64 %; SUVmax, 35.16 ± 12.59 %). CONCLUSIONS: Despite different attenuation correction approaches, the SUV of PET-positive lesions correlated well between hybrid PET/MR and contrast-enhanced PET/CT. However Dixon MR images acquired for attenuation correction were insufficient to provide anatomic information of PET images because of low spatial resolution. Thus, additional MR sequence with fast and higher resolution may be necessary for anatomic information.

MR differentiation of low-grade chondrosarcoma from enchondroma.

PURPOSE: To evaluate magnetic resonance (MR) imaging for the discrimination between low-grade chondrosarcoma and enchondroma. MATERIALS AND METHODS: MR images of 34 patients who were confirmed with low-grade chondrosarcoma or enchondroma were retrospectively reviewed. After review of medical records, MR findings in 18 patients with low-grade chondrosarcoma and 16 patients with enchondroma were compared. MR images were retrospectively reviewed for the lesion location (central or eccentric; epiphysis, metaphysic, or diaphysis), margin, contour, mineralized matrix, endosteal scalloping, cortical expansion, cortical destruction, soft tissue mass formation, and periosteal reaction. Signal intensity, the patterns of contrast enhancement (unilocular or multilobular), soft tissue mass, and adjacent abnormal bone marrow and soft tissue signal were also reviewed. Statistical analysis was performed with chi-square test. RESULTS: The patients with low-grade chondrosarcoma had a significantly higher incidence of MR findings (P<.05): predominantly intermediate signal on T1-weighted images [72% (13/18) in low-grade chondrosarcoma vs. 25% (4/16) in enchondroma], multilocular appearance on contrast-enhanced T1-weighted images [83% (15/18) vs. 44% (7/16)], cortical destruction [33% (6/18) vs. 0% (0/16)], a soft tissue mass [28% (5/18) vs. 0% (0/16)], adjacent bone marrow and soft tissue abnormal signal [22% (4/18) vs. 0% (0/16)], and an involvement of the epiphysis or flat bone [56% (10/18) vs. 19% (3/16)]. CONCLUSION: MR imaging shows helpful features for differentiating low-grade chondrosarcoma from enchondroma.

Brain SPECT Analysis After Constraint-Induced Movement Therapy in Young Children with Hemiplegic Cerebral Palsy: Case Report.

Constraint-induced movement therapy (CIMT) was shown recently to be promising for improving upper-limb function in children with cerebral palsy (CP). This study investigated the changes in cerebral perfusion with single-photon emission computerized tomography (SPECT) after modified CIMT (child-friendly CIMT) in young hemiplegic girls. Two young children with left hemiplegic CP were studied with SPECT at rest before and after the CIMT period, and they also performed standardized upper motor function tests [Jebsen hand function test, quality of upper extremity skills test (QUEST), and dynamic electromyography (EMG)]. The cerebral perfusion SPECT revealed regional perfusion increase in the motor cortex area in the affected hemisphere, and the changes associated with functional gain. Our cases showed that intensive movement therapy appears to change local cerebral perfusion and SPECT could show these changes in children with hemiplegic CP.

Extracranial skeletal Langerhans cell histiocytosis: MR imaging features according to the radiologic evolutional phases.

PURPOSE: The purpose was to describe the magnetic resonance (MR) findings of extracranial skeletal Langerhans cell histiocytosis according to the radiologic evolutional phases. MATERIALS AND METHODS: Twenty-two patients with pathologically confirmed extracranial skeletal Langerhans cell histiocytosis were included. The lesions were classified as early, mid, and late phases according to the radiologic evolutional phases. MR images were retrospectively analyzed regarding signal intensity, internal hypointense band, fluid levels, periosteal reaction, adjacent bone marrow and soft tissue abnormal signal, and patterns of contrast enhancement in each phase. RESULTS: According to the radiologic evolutional phases, there were 4 patients with early phase, 16 with mid phase, and 2 with late phase. All cases showed hypointense to intermediate signal intensity on T1-weighted images. On T2-weighted images, 12 (55%) of the 22 lesions were hyperintense, and 10 (45%) showed intermediate signal. All lesions showed diffusely heterogeneous signal on T2-weighted images. Internal low-signal bands of the lesions were observed in 13 cases (59%). There were two cases with fluid levels in mid phase. Periosteal reaction was observed in 13 (59%) cases. Adjacent bone marrow or soft tissue abnormal signal was observed in 20 cases (91%), respectively. According to early, mid, and late phases, bone marrow and soft tissue abnormal signals were observed in 100%, 100%, and 0% cases, respectively. Soft tissue mass was seen in eight cases (36%). Ten (46%) lesions showed cortical destruction, including one patient with a pathologic fracture. Among 21 patients with contrast infusion, diffuse enhancement was observed in 19 patients (90%), and marginal and septal enhancement was seen in 2 patients (10%). CONCLUSION: MR imaging was helpful in the diagnosis of extracranial skeletal Langerhans cell histiocytosis, particularly in early and mid phases.

Freiberg's disease: quantitative assessment of osteonecrosis on three-dimensional CT.

BACKGROUND: The extent of necrosis is the main determining factor in the outcome of osteonecrosis. There is no method for measuring the extent of osteonecrosis of the metatarsal head in Freiberg's disease. The purpose of this study was to determine the reliability and prognostic ability of a new method for measurement of the extent of osteonecrosis in Freiberg's disease on three-dimensional computed tomography. METHODS: A retrospective review of 11 cases with symptomatic Freiberg's disease in ten patients (5 males and 5 females; mean age, 27 years) undergoing computed tomography between July 2005 and September 2007 was performed. Two investigators (K.A.C. and H.K.O.) used a new method to measure the necrotic extent of the metatarsal head: the necrotic angle ratio of necrotic arc angle to normal arc angle of the articular surface on the sagittal reconstruction image of computed tomography. The interobserver reliability was determined for computed tomography measurement. Correlation between the Smillie staging using radiographs and the necrotic angle ratio on computed tomography was also evaluated. RESULTS: One patient presented with stage I disease (Smillie staging), one with stage II, two with stage III, five with stage IV, and two with stage V, respectively. The necrotic angle ratio of the metatarsal head was 14% in stage I, 21% in stage II, 34% in stage III, 43% in stage IV, and 53% in stage V. The interobserver reliability for computed tomography measurement was high (Cronbach α=0.96). We found the increase of the necrotic extent in proportion to the Smillie stage. The Smillie staging using radiographs and the necrotic angle ratio on computed tomography were significantly correlated. (P<0.05) CONCLUSIONS: Three-dimensional computed tomography measurement of the necrotic extent of the metatarsal head is a reliable and useful method in evaluating the staging of Freiberg's disease and may eventually help to optimize treatment.