Clinical and Radiological Features of Korean Patients With Anti-HMGCR Myopathy

Background@#and Purpose To understand the characteristics of Korean patients with anti-3-hydroxy-3-methylglutaryl-coenxyme A reductase (HMGCR) myopathy, we measured antiHMGCR antibodies and analyzed the clinical, radiological, and pathological features of patients with anti-HMGCR myopathy. @*Methods@#We measured titers of anti-HMGCR antibodies in the sera of 99 patients with inflammatory myopathy, 36 patients with genetic myopathy, and 63 healthy subjects using an enzyme-linked immunosorbent assay. We tested 16 myositis-specific autoantibodies (MSAs) in all patients with anti-HMGCR myopathy. @*Results@#Positivity for the anti-HMGCR antibody was observed in 17 (4 males and 13 females) of 99 patients with inflammatory myopathy. The median age at symptom onset was 60 years.Ten (59%) of the patients with anti-HMGCR positivity had taken statins. The titer of antiHMGCR antibodies was significantly higher in the statin-naïve group (median=230 U/mL, interquartile range=170–443 U/mL) than in the statin-exposed group (median=178 U/mL, interquartile range=105–210 U/mL, p=0.045). The most common symptom was proximal muscle weakness in 15 patients (88%), followed by myalgia in 9 (53%), neck weakness in 4 (24%), dysphagia in 3 (18%), and skin lesions in 2 (12%). The median titer of anti-HMGCR antibody was 202 U/mL. We found eight different MSAs in nine (53%) patients. The median disease duration from symptom onset to diagnosis was significantly shorter in the MSA-positive group than in the MSA-negative group (p=0.027). @*Conclusions@#Our study was the first to measure anti-HMGCR antibodies in inflammatory myopathy. It has provided new findings, including the suggestion of the coexistence of other MSAs in Korean patients.

Artificial Intelligence and Deep Learning in Musculoskeletal Magnetic Resonance Imaging

The application of artificial intelligence (AI) and deep learning (DL) in radiology is rapidly evolving. AI in healthcare has benefits for image recognition, classification, and radiological workflows from a clinical perspective. Additionally, clinical triage AI can be applied to triage systems. This review aims to introduce the concept of DL and discuss its applications in the interpretation of magnetic resonance (MR) images and the DL-based reconstruction of accelerated MR images, with an emphasis on musculoskeletal radiology. The most recent developments and future directions are also discussed briefly.

Artificial intelligence in musculoskeletal ultrasound imaging

Ultrasonography (US) is noninvasive and offers real-time, low-cost, and portable imaging that facilitates the rapid and dynamic assessment of musculoskeletal components. Significant technological improvements have contributed to the increasing adoption of US for musculoskeletal assessments, as artificial intelligence (AI)-based computer-aided detection and computer-aided diagnosis are being utilized to improve the quality, efficiency, and cost of US imaging. This review provides an overview of classical machine learning techniques and modern deep learning approaches for musculoskeletal US, with a focus on the key categories of detection and diagnosis of musculoskeletal disorders, predictive analysis with classification and regression, and automated image segmentation. Moreover, we outline challenges and a range of opportunities for AI in musculoskeletal US practice.

Ossification of the Transverse Ligament of the Atlas on CT: Frequency and Associated Findings

Purpose@#To determine the frequency of ossification of the transverse ligament of the atlas (OTLA) and to investigate the associated findings on cervical spine CT and plain radiography. @*Materials and Methods@#We reviewed 5201 CT scans of the cervical spine of 3975 consecutive patients over an 11-year period for the presence of OTLA and compared them with those of ageand sex-matched controls. The frequency and associated findings of OTLA were investigated and statistically correlated. @*Results@#The overall frequency of OTLA was 1.1% (45 of 3975 patients) and increased with age (p < 0.005). The frequency of OTLA in patients over 80 years was 12%. The space available for the spinal cord (SAC) was smaller in patients with OTLA (p < 0.005). Mineralization of the complex of the anterior atlantooccipital membrane and Barkow ligament, ossification of the ligamentum flavum, and kyphosis of the cervical spine positively correlated to the presence of OTLA (p < 0.005). @*Conclusion@#OTLA was associated with age, SAC narrowing, cervical kyphosis, and ossification of other cervical ligaments and may be associated with degenerative spondylosis, systemic hyperostotic status, or mechanical stress or instability.

Optimization of MRI Protocol for the Musculoskeletal System

Magnetic resonance imaging (MRI) is an essential modality for the diagnosis of musculoskeletal system defects because of its higher soft-tissue contrast and spatial resolution. With the recent development of MRI-related technology, faster imaging and various image plane reconstructions are possible, enabling better assessment of three-dimensional musculoskeletal anatomy and lesions. Furthermore, the image quality, diagnostic accuracy, and acquisition time depend on the MRI protocol used. Moreover, the protocol affects the efficiency of the MRI scanner. Therefore, it is important for a radiologist to optimize the MRI protocol. In this review, we will provide guidance on patient positioning; selection of the radiofrequency coil, pulse sequences, and imaging planes; and control of MRI parameters to help optimize the MRI protocol for the six major joints of the musculoskeletal system.

Ultrasound Feature-Based Diagnostic Model Focusing on the “Submarine Sign” for Epidermal Cysts among Superficial Soft Tissue Lesions

OBJECTIVE: To develop a diagnostic model for superficial soft tissue lesions to differentiate epidermal cyst (EC) from other lesions based on ultrasound (US) features. MATERIALS AND METHODS: This retrospective study included 205 patients who had undergone US examinations for superficial soft tissue lesions and subsequent surgical excision. The study population was divided into the derivation set (n = 112) and validation set (n = 93) according to the imaging date. The following US features were analyzed to determine those that could discriminate EC from other lesions: more-than-half-depth involvement of the dermal layer, “submarine sign” (focal projection of the hypoechoic portion to the epidermis), posterior acoustic enhancement, posterior wall enhancement, morphology, shape, echogenicity, vascularity, and perilesional fat change. Using multivariable logistic regression, a diagnostic model was constructed and visualized as a nomogram. The performance of the diagnostic model was assessed by calculating the area under the curve (AUC) of the receiver operating characteristic curve and calibration plot in both the derivation and validation sets. RESULTS: More-than-half-depth involvement of the dermal layer (odds ratio [OR] = 3.35; p = 0.051), “submarine sign” (OR = 12.2; p < 0.001), and morphology (OR = 5.44; p = 0.002) were features that outweighed the others when diagnosing EC. The diagnostic model based on these features showed good discrimination ability in both the derivation set (AUC = 0.888, 95% confidence interval [95% CI] = 0.825–0.950) and validation set (AUC = 0.902, 95% CI = 0.832–0.972). CONCLUSION: More-than-half-depth of involvement of the dermal layer, “submarine sign,” and morphology are relatively better US features than the others for diagnosing EC.

Experiences of localization and removal of non-palpable subdermal contraceptive implants with ultrasound

OBJECTIVE: The aim of this study was to present experiences in localization and removal of non-palpable subdermal contraceptive implants with ultrasonography. METHODS: Medical records from January 1, 2016, to April 30, 2018, were retrospectively reviewed for 21 patients who were referred to a single institution and had an impalpable implant despite following the removal instruction. In all the cases, more than one attempt was made to remove the implant before referral. The rod was detected using radiography and ultrasonography. In all the cases, localization of the single implant was achieved with ultrasonography. The distal depth of the rod was measured, and skin marking was made following the echogenicity. The implants were subsequently removed under anesthesia. RESULTS: In 18 cases, the rods were localized using ultrasonography and successfully removed under local anesthesia. In the other three cases, removal with local anesthesia failed. Although the rod was detected successful with ultrasonography, the implants were removed under general anesthesia in the operating room. The depth from skin to rod, measured with ultrasonography, was >12.0 mm in all the cases and located deep in the muscular layer in the failure cases. The depth of the implants positively correlated with the time spent for removal (r=0.525; P=0.015). CONCLUSION: High frequency ultrasonography is a highly accurate tool for localization and measurement of the skin-to-rod depth. It is also useful for removing non-palpable implants. If the depth of the implant is >12.0 mm, removal of the implant in the operating room under general anesthesia is recommended.

Gelatinous Transformation of Bone Marrow Mimicking Malignant Marrow-Replacing Lesion on Magnetic Resonance Imaging in a Patient without Underlying Devastating Disease

Gelatinous transformation of bone marrow is characterized by hypoplasia of fat cells with focal loss of hematopoietic cells and deposition of extracellular gelatinous substances. It is known to be associated with devastating underlying diseases that starve bone marrow. Here, we present a case of a patient whose magnetic resonance (MR) imaging findings of vertebral column were interpreted as metastasis or hematologic malignancy, however, the final diagnosis revealed a gelatinous transformation of bone marrow. This is the first report of gelatinous transformation of bone marrow without evidence of underlying devastating disease.

Status of Interchange of Medical Imaging in Korea: A Questionnaire Survey of Physicians

The purpose of this study was to summarize the results of a survey for physicians with specialties other than radiology about imaging studies of patients referred from other institutions. The survey was promoted through individual contacts or social network service and physicians who voluntarily responded to the survey were the subjects of the study. The questionnaire consisted of 11 questions about basic information and referrals about medical imaging. A total of 160 physicians from 30 specialties participated in the survey and 95.6% of the respondents worked in tertiary care center or general hospital. Patients were frequently referred with outside medical images. The most frequently referred imaging modalities were computed tomography and magnetic resonance imaging. However, radiological reports from outside institutions were rarely referred. Most physicians thought that reinterpretation for outside imaging is necessary to acquire a secondary opinion. In conclusion, considering that outside radiological reports are frequently missing and there are high demands on reinterpretation for outside imaging, guidelines for referral of radiological reports with medical imaging, basic elements of radiological reports, and reinterpretation need to be developed.

Suggested Protocol for Efficient Medical Image Information Exchange in Korea: Breast MRI

PURPOSE@#Establishment of an appropriate protocol for breast magnetic resonance imaging (MRI) in the study of image quality standards to enhance the effectiveness of medical image information exchange, which is part of the construction and activation of clinical information exchange for healthcare informatization.@*MATERIALS AND METHODS@#The recommended protocols of breast and MRI scans were reviewed and the questionnaire was prepared by a responsible researcher. Then, a panel of 9 breast dedicated radiologists was set up in Korea. The expert panel conducted a total of three Delphi agreements to draw up a consensus on the breast MRI protocol.@*RESULTS@#The agreed breast MRI recommendation protocol is a 1.5 Tesla or higher device that acquires images with prone position using a breast dedicated coil and includes T2-weighted and pre-contrast T1-weighted images. Contrast enhancement images are acquired at least two times, and include 60–120 seconds between images and after 4 minutes. The contrast enhancement T1-weighted image should be less than 3 mm in thickness, less than 120 seconds in temporal resolution, and less than 1.5 mm² in-plane pixel resolution.@*CONCLUSION@#The Delphi agreement of the domestic breast imaging specialist group has established the recommendation protocol of the effective breast MRI.

Utility of False Profile View for Screening of Ischiofemoral Impingement / 대한고관절학회지

PURPOSE: Ischiofemoral impingement (IFI)-primarily diagnosed by magnetic resonance imaging (MRI)-is an easily overlooked disease due to its low incidence. The purpose of this study was to evaluate the usefulness of false profile view as a screening test for IFI. MATERIALS AND METHODS: Fifty-eight patients diagnosed with IFI between June 2013 and July 2017 were enrolled in this retrospective study. A control group (n=58) with matching propensity scores (age, gender, and body mass index) were also included. Ischiofemoral space (IFS) was measured as the shortest distance between the lateral cortex of the ischium and the medial cortex of lesser trochanter in weight bearing hip anteroposterior (AP) view and false profile view. MRI was used to measure IFS and quadratus femoris space (QFS). The receiver operating characteristics (ROC), area under the ROC curve (AUC) and cutoff point of the IFS were measured by false profile images, and the correlation between the IFS and QFS was analyzed using the MRI scans. RESULTS: In the false profile view and hip AP view, patients with IFI had significantly decreased IFS (P < 0.01). In the false profile view, ROC AUC (0.967) was higher than in the hip AP view (0.841). Cutoff value for differential diagnosis of IFI in the false profile view was 10.3 mm (sensitivity, 88.2%; specificity, 88.4%). IFS correlated with IFS (r=0.744) QFS (0.740) in MRI and IFS (0.621) in hip AP view (P < 0.01). CONCLUSION: IFS on false profile view can be used as a screening tool for potential IFI.

Rapid, Objective and Non-invasive Diagnosis of Sudomotor Dysfunction in Patients With Lower Extremity Dysesthesia: A Cross-Sectional Study

OBJECTIVE: To determine whether patients with lumbosacral (LS) radiculopathy and peripheral polyneuropathy (PPNP) exhibit sudomotor abnormalities and whether SUDOSCAN (Impeto Medical, Paris, France) can complement nerve conduction study (NCS) and electromyography (EMG). METHODS: Outpatients with lower extremity dysesthesia underwent electrophysiologic studies and SUDOSCAN. They were classified as normal (group A), LS radiculopathy (group B), or PPNP (group C). Pain severity was measured by the Michigan Neuropathy Screening Instrument (MNSI) and visual analogue scale (VAS). Demographic features, electrochemical skin conductance (ESC) values on hands and feet, and SUDOSCAN-risk scores were analyzed. RESULTS: There were no statistical differences in MNSI and VAS among the three groups. Feet-ESC and hands-ESC values in group C were lower than group A and B. SUDOSCAN-risk score in group B and C was higher than group A. With a cut-off at 48 microSiemens of feet-ESC, PPNP was detected with 57.1% sensitivity and 94.2% specificity (area under the curve [AUC]=0.780; 95% confidence interval [CI], 0646–0.915). With a SUDOSCAN-risk score cut-off at 29%, NCS and EMG abnormalities related to LS radiculopathy and PPNP were detected with 64.1% sensitivity and 84.2% specificity (AUC=0.750; 95% CI, 0.674–0.886). CONCLUSION: SUDOSCAN can discriminate outpatients with abnormal electrophysiological findings and sudomotor dysfunction. This technology may be a complementary tool to NCS and EMG in outpatients with lower extremity dysesthesia.

Interobserver and Test-Retest Reproducibility of T1ρ and T2 Measurements of Lumbar Intervertebral Discs by 3T Magnetic Resonance Imaging

OBJECTIVE: To investigate the interobserver and test-retest reproducibility of T1ρ and T2 measurements of lumbar intervertebral discs using 3T magnetic resonance imaging (MRI). MATERIALS AND METHODS: This study included a total of 51 volunteers (female, 26; male, 25; mean age, 54 ± 16.3 years) who underwent lumbar spine MRI with a 3.0 T scanner. Amongst these subjects, 40 underwent repeat T1ρ and T2 measurement acquisitions with identical image protocol. Two observers independently performed the region of interest measurements in the nuclei pulposi of the discs from L1–2 through L5–S1 levels. Statistical analysis was performed using intraclass correlation coefficient (ICC) with a two-way random model of absolute agreement. Comparison of the ICC values was done after acquisition of ICC values using Z test. Statistical significance was defined as p value < 0.05. RESULTS: The ICCs of interobserver reproducibility were 0.951 and 0.672 for T1ρ and T2 mapping, respectively. The ICCs of test-retest reproducibility (40 subjects) for T1ρ and T2 measurements were 0.922 and 0.617 for observer A and 0.914 and 0.628 for observer B, respectively. In the comparison of the aforementioned ICCs, ICCs of interobserver and test-retest reproducibility for T1ρ mapping were significantly higher than T2 mapping (p < 0.001). CONCLUSION: The interobserver and test-retest reproducibility of T1ρ mapping were significantly higher than those of T2 mapping for the quantitative assessment of nuclei pulposi of lumbar intervertebral discs.

Difference in Bone Mineral Density Change at the Lateral Femoral Cortices according to Administration of Different Bisphosphonate Agents

BACKGROUND: To retrospectively assess whether the response of subtrochanteric lateral cortex (STLC) is different according to the bisphosphonate agents in terms of bone mineral density (BMD) change. METHODS: A total of 149 subjects, who had 2- to 4-year interval follow-up of BMD using dual energy X-ray absorptiometry (DXA), were included in this retrospective study divided into following 3 groups: control group (no consumption of any anti-osteoporotic drugs, n=38), alendronate group (naïve alendronate users, n=48), risedronate group (naïve risedronate users, n=63). BMD was measured at the STLC and subtrochanteric medial cortex (STMC) in each patient by drawing rectangular ROIs at the bone cortices. The percent change of BMD at the STLC were compared between the aforementioned 3 groups by using analysis of covariance model to control five independent variables of age, body mass index, percent change of STMC, hip axis length, time interval between DXA examinations. RESULTS: The least square mean values±standard deviation of the percent change of BMD in the control, alendronate, and risedronate groups were 1.46±1.50, 2.23±1.26, and 6.96±1.11, respectively. The risedronate group showed significantly higher change of BMD percentage compared with the control (adjusted P=0.012) or alendronate (adjusted P=0.016) groups. CONCLUSIONS: The percent change of BMD at the STLC in the risedronate user group was greater than the alendronate and control groups. The implication of these changes needs to be further verified.

Comparison of Multi-Echo Dixon Methods with Volume Interpolated Breath-Hold Gradient Echo Magnetic Resonance Imaging in Fat-Signal Fraction Quantification of Paravertebral Muscle

OBJECTIVE: To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2* estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2*-corrected two-echo Dixon or T2*-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard. MATERIALS AND METHODS: Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2*-corrected Dixon technique with two (non-T2*-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences. RESULTS: A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 +/- 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (p < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (p < 0.001), as compared with two- or three-echo methods. CONCLUSION: T2*-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification.

Prevalence, Distribution, and Significance of Incidental Thoracic Ossification of the Ligamentum Flavum in Korean Patients with Back or Leg Pain : MR-Based Cross Sectional Study

OBJECTIVE: Thoracic ossification of the ligamentum flavum (OLF) is a relatively rare disease. Because of ambiguous clinical symptom, it is difficult for early diagnosis of OLF and subsequent treatment can be delayed or missed. Therefore, the purpose of this study is to comprehensively assess the prevalence and distribution of thoracic OLF by magnetic resonance imaging (MRI) and coexisting spinal disease in Korean patients with back pain or leg pain. METHODS: The sample included 2134 Korean patients who underwent MRI evaluation for back pain. The prevalence and distribution of thoracic OLF were assessed using lumbar MRI with whole spine sagittal images. Additionally, we examined the presence of coexisting lumbar and cervical diseases. The presence of thoracic OLF as well as clinical parameters such as age, sex, and surgery were retrospectively reviewed. RESULTS: The prevalence of thoracic OLF in total patients was 16.9% (360/2134). The prevalence tended to increase with aging and was higher in women than in men. The lower thoracic segment of T10-11 was the most frequently affected segment. Of the 360 patients with OLF, 31.9% had coexisting herniated thoracic discs at the same level. Approximately 74% of the patients with OLF had coexisting lumbar and cervical disease. Nine (2.5%) of 360 OLF patients underwent surgery for thoracic lesion. CONCLUSION: The prevalenceof thoracic OLF was relatively higher than those of previous reports. And coexisting lumbar and cervical disease were very frequent. Therefore, we should check coexisting spinal diseases and the exact diagnostic localization of ossification besides lumbar disease.

Accuracy of Diffusion Tensor Imaging for Diagnosing Cervical Spondylotic Myelopathy in Patients Showing Spinal Cord Compression

OBJECTIVE: To assess the performance of diffusion tensor imaging (DTI) for the diagnosis of cervical spondylotic myelopathy (CSM) in patients with deformed spinal cord but otherwise unremarkable conventional magnetic resonance imaging (MRI) findings. MATERIALS AND METHODS: A total of 33 patients who underwent MRI of the cervical spine including DTI using two-dimensional single-shot interleaved multi-section inner volume diffusion-weighted echo-planar imaging and whose spinal cords were deformed but showed no signal changes on conventional MRI were the subjects of this study. Mean diffusivity (MD), longitudinal diffusivity (LD), radial diffusivity (RD), and fractional anisotropy (FA) were measured at the most stenotic level. The calculated performance of MD, FA, MD∩FA (considered positive when both the MD and FA results were positive), LD∩FA (considered positive when both the LD and FA results were positive), and RD∩FA (considered positive when both the RD and FA results were positive) in diagnosing CSM were compared with each other based on the estimated cut-off values of MD, LD, RD, and FA from receiver operating characteristic curve analysis with the clinical diagnosis of CSM from medical records as the reference standard. RESULTS: The MD, LD, and RD cut-off values were 1.079 × 10⁻³, 1.719 × 10⁻³, and 0.749 × 10⁻³ mm²/sec, respectively, and that of FA was 0.475. Sensitivity, specificity, positive predictive value and negative predictive value were: 100 (4/4), 44.8 (13/29), 20 (4/20), and 100 (13/13) for MD; 100 (4/4), 27.6 (8/29), 16 (4/25), and 100 (8/8) for FA; 100 (4/4), 58.6 (17/29), 25 (4/16), and 100 (17/17) for MD∩FA; 100 (4/4), 68.9 (20/29), 30.8 (4/13), and 100 (20/20) for LD∩FA; and 75 (3/4), 68.9 (20/29), 25 (3/12), and 95.2 (20/21) for RD∩FA in percentage value. Diagnostic performance comparisons revealed significant differences only in specificity between FA and MD∩FA (p = 0.003), FA and LD∩FA (p < 0.001), FA and RD∩FA (p < 0.001), MD and LD∩FA (p = 0.024) and MD and RD∩FA (p = 0.024). CONCLUSION: Fractional anisotropy combined with MD, RD, or LD is expected to be more useful than FA and MD for diagnosing CSM in patients who show deformed spinal cords without signal changes on MRI.

Dual-Energy Computed Tomography Arthrography of the Shoulder Joint Using Virtual Monochromatic Spectral Imaging: Optimal Dose of Contrast Agent and Monochromatic Energy Level

OBJECTIVE: To optimize the dose of contrast agent and the level of energy for dual-energy computed tomography (DECT) arthrography of the shoulder joint and to evaluate the benefits of the optimized imaging protocol. MATERIALS AND METHODS: Dual-energy scans with monochromatic spectral imaging mode and conventional single energy scans were performed on a shoulder phantom with 10 concentrations from 0 to 210 mg/mL of iodinated contrast medium at intervals of 15 or 30 mg/mL. Image noise, tissue contrast, and beam hardening artifacts were assessed to determine the optimum dose of contrast agent and the level of monochromatic energy for DECT shoulder arthrography in terms of the lowest image noise and the least beam hardening artifacts while good tissue contrast was maintained. Material decomposition (MD) imaging for bone-iodine differentiation was qualitatively assessed. The optimized protocol was applied and evaluated in 23 patients. RESULTS: The optimal contrast dose and energy level were determined by the phantom study at 60 mg/mL and 72 keV, respectively. This optimized protocol for human study reduced the image noise and the beam-hardening artifacts by 35.9% and 44.5%, respectively. Bone-iodine differentiation by MD imaging was not affected by the iodine concentration or level of energy. CONCLUSION: Dual-energy scan with monochromatic spectral imaging mode results in reduced image noise and beam hardening artifacts.

Differentiation between Focal Malignant Marrow-Replacing Lesions and Benign Red Marrow Deposition of the Spine with T2*-Corrected Fat-Signal Fraction Map Using a Three-Echo Volume Interpolated Breath-Hold Gradient Echo Dixon Sequence

OBJECTIVE: To assess the feasibility of T2*-corrected fat-signal fraction (FF) map by using the three-echo volume interpolated breath-hold gradient echo (VIBE) Dixon sequence to differentiate between malignant marrow-replacing lesions and benign red marrow deposition of vertebrae. MATERIALS AND METHODS: We assessed 32 lesions from 32 patients who underwent magnetic resonance imaging after being referred for assessment of a known or possible vertebral marrow abnormality. The lesions were divided into 21 malignant marrow-replacing lesions and 11 benign red marrow depositions. Three sequences for the parameter measurements were obtained by using a 1.5-T MR imaging scanner as follows: three-echo VIBE Dixon sequence for FF; conventional T1-weighted imaging for the lesion-disc ratio (LDR); pre- and post-gadolinium enhanced fat-suppressed T1-weighted images for the contrast-enhancement ratio (CER). A region of interest was drawn for each lesion for parameter measurements. The areas under the curve (AUC) of the parameters and their sensitivities and specificities at the most ideal cutoff values from receiver operating characteristic curve analysis were obtained. AUC, sensitivity, and specificity were respectively compared between FF and CER. RESULTS: The AUCs of FF, LDR, and CER were 0.96, 0.80, and 0.72, respectively. In the comparison of diagnostic performance between the FF and CER, the FF showed a significantly larger AUC as compared to the CER (p = 0.030), although the difference of sensitivity (p = 0.157) and specificity (p = 0.157) were not significant. CONCLUSION: Fat-signal fraction measurement using T2*-corrected three-echo VIBE Dixon sequence is feasible and has a more accurate diagnostic performance, than the CER, in distinguishing benign red marrow deposition from malignant bone marrow-replacing lesions.

Four-Dimensional Real-Time Cine Images of Wrist Joint Kinematics Using Dual Source CT with Minimal Time Increment Scanning

PURPOSE: To validate the feasibility of real time kinematography with four-dimensional (4D) dynamic functional wrist joint imaging using dual source CT. MATERIALS AND METHODS: Two healthy volunteers performed radioulnar deviation and pronation-supination wrist motions for 10 s and 4 s per cycle in a dual source CT scanner. Scan and reconstruction protocols were set to optimize temporal resolution. Cine images of the reconstructed carpal bone of the moving wrist were recorded. The quality of the images and radiation dosage were evaluated. RESULTS: The 4D cine images obtained during 4 s and 10 s of radioulnar motion showed a smooth stream of movement with good quality and little noise or artifact. Images from the pronation-supination motion showed noise with a masked surface contour. The temporal resolution was optimized at 0.28 s. CONCLUSION: Using dual source CT, 4D cine images of in vivo kinematics of wrist joint movement were obtained and found to have a shorter scan time, improved temporal resolution and lower radiation dosages compared with those previously reported.