High-Resolution Cone-Beam Computed Tomography is a Fast and Promising Technique to Quantify Bone Microstructure and Mechanics of the Distal Radius.

Obtaining high-resolution scans of bones and joints for clinical applications is challenging. HR-pQCT is considered the best technology to acquire high-resolution images of the peripheral skeleton in vivo, but a breakthrough for widespread clinical applications is still lacking. Recently, we showed on trapezia that CBCT is a promising alternative providing a larger FOV at a shorter scanning time. The goals of this study were to evaluate the accuracy of CBCT in quantifying trabecular bone microstructural and predicted mechanical parameters of the distal radius, the most often investigated skeletal site with HR-pQCT, and to compare it with HR-pQCT. Nineteen radii were scanned with four scanners: (1) HR-pQCT (XtremeCT, Scanco Medical AG, @ (voxel size) 82 µm), (2) HR-pQCT (XtremeCT-II, Scanco, @60.7 µm), (3) CBCT (NewTom 5G, Cefla, @75 µm) reconstructed and segmented using in-house developed software and (4) microCT (VivaCT40, Scanco, @19 µm-gold standard). The following parameters were evaluated: predicted stiffness, strength, bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), separation (Tb.Sp) and number (Tb.N). The overall accuracy of CBCT with in-house optimized algorithms in quantifying bone microstructural parameters was comparable (R2 = 0.79) to XtremeCT (R2 = 0.76) and slightly worse than XtremeCT-II (R2 = 0.86) which were both processed with the standard manufacturer's technique. CBCT had higher accuracy for BV/TV and Tb.Th but lower for Tb.Sp and Tb.N compared to XtremeCT. Regarding the mechanical parameters, all scanners had high accuracy (R2 [Formula: see text] 0.96). While HR-pQCT is optimized for research, the fast scanning time and good accuracy renders CBCT a promising technique for high-resolution clinical scanning.

Trapeziometacarpal stabilization through dorsoradial ligament reconstruction: An early post-surgery in vivo biomechanical analyses.

Ligament reconstruction can provide pain relief in patients with a painful, unstable, pre-arthritic trapeziometacarpal (TMC) joint. Imbrication of the dorsoradial ligament (DRL) has been proposed as a minimal invasive stabilization technique. It requires less invasive surgery than an Eaton-Littler technique and shows promising long-term clinical outcome. We used dynamic CT to objectively review the effects of the imbrication. Four patients with pain and laxity at the TMC joint, but without radiographic signs of osteoarthritis, were recruited. Dynamic CT scans were made during active thumb abduction-adduction, flexion-extension, and two functional grip tasks using a radiolucent jig. Scans of the patients were acquired before and 3 to 6 months after DRL reconstruction. Motion of each bone in the articular chain of the thumb was quantified. In addition, we mapped changes in the contact patterns between the articular facets during the entire thumb motion. After DRL imbrication, we found no overall decrease in MC1 movement in three out of four patients. Furthermore, no increase in TMC joint congruency, defined as proximity area size, was found for three out of four patients. Pre- and post-operative differences in congruency across different tasks were patient-dependent and relatively small. We demonstrated that, from a biomechanical perspective, there is high variability in post-operative outcome between patients that undergo identical surgical procedures performed by the same surgeon. A post-operative decrease in range of motion, increase in joint congruency or decrease in proximity area shift during thumb motion is not omnipresent. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2851-2864, 2018.

Clinical evaluation of a medical high dynamic range display.

PURPOSE: Recent new medical displays do have higher contrast and higher luminance but do not have a High Dynamic Range (HDR). HDR implies a minimum luminance value close to zero. A medical HDR display prototype based on two Liquid Crystal layers has been developed. The goal of this study is to evaluate the potential clinical benefit of such display in comparison with a low dynamic range (LDR) display. METHODS: The study evaluated the clinical performance of the displays in a search and detection task. Eight radiologists read chest x-ray images some of which contained simulated lung nodules. The study used a JAFROC (Jacknife Free Receiver Operating Characteristic) approach for analyzing FROC data. The calculated figure of merit (FoM) is the probability that a lesion is rated higher than all rated nonlesions on all images. Time per case and accuracy for locating the center of the nodules were also compared. The nodules were simulated using Samei's model. 214 CR and DR images [half were "healthy images" (chest nodule-free) and half "diseased images"] were used resulting in a total number of nodules equal to 199 with 25 images with 1 nodule, 51 images with 2 nodules, and 24 images with 3 nodules. A dedicated software interface was designed for visualizing the images for each session. For the JAFROC1 statistical analysis, the study is done per nodule category: all nodules, difficult nodules, and very difficult nodules. RESULTS: For all nodules, the averaged FoMHDR is slightly higher than FoMLDR with 0.09% of difference. For the difficult nodules, the averaged FoMHDR is slightly higher than FoMLDR with 1.38% of difference. The averaged FoMHDR is slightly higher than FoMLDR with 0.71% of difference. For the true positive fraction (TPF), both displays (the HDR and the LDR ones) have similar TPF for all nodules, but looking at difficult and very difficult nodules, there are more TP for the HDR display. The true positive fraction has been also computed in function of the local average luminance around the nodules. For the lowest luminance range, there is more than 30% in favor of the HDR display. For the highest luminance range, there is less than 6% in favor of the LDR display. CONCLUSIONS: This study shows the potential benefit of using a HDR display in radiology.

Computed tomographic analysis of the quality of trunk muscles in asymptomatic and symptomatic lumbar discectomy patients.

BACKGROUND: No consensus exists on how rehabilitation programs for lumbar discectomy patients with persistent complaints after surgery should be composed. A better understanding of normal and abnormal postoperative trunk muscle condition might help direct the treatment goals. METHODS: A three-dimensional CT scan of the lumbar spine was obtained in 18 symptomatic and 18 asymptomatic patients who had undergone a lumbar discectomy 42 months to 83 months (median 63 months) previously. The psoas muscle (PS), the paraspinal muscle mass (PA) and the multifidus muscle (MF) were outlined at the L3, L4 and L5 level. Of these muscles, fat free Cross Sectional Area (CSA) and fat CSA were determined. CSA of the lumbar erector spinae (LES = longissimus thoracis + iliocostalis lumborum) was calculated by subtracting MF CSA from PA CSA. Mean muscle CSA of the left and right sides was calculated at each level. To normalize the data for interpersonal comparison, the mean CSA was divided by the CSA of the L3 vertebral body (mCSA = normalized fat-free muscle CSA; fCSA = normalized fat CSA). Differences in CSA between the pain group and the pain free group were examined using a General Linear Model (GLM). Three levels were examined to investigate the possible role of the level of operation. RESULTS: In lumbar discectomy patients with pain, the mCSA of the MF was significantly smaller than in pain-free subjects (p = 0.009) independently of the level. The mCSA of the LES was significantly smaller in pain patients, but only on the L3 slice (p = 0.018). No significant difference in mCSA of the PS was found between pain patients and pain-free patients (p = 0.462). The fCSA of the MF (p = 0.186) and of the LES (p = 0.256) were not significantly different between both populations. However, the fCSA of the PS was significantly larger in pain patients than in pain-free patients. (p = 0.012).The level of operation was never a significant factor. CONCLUSIONS: CT comparison of MF, LES and PS muscle condition between lumbar discectomy patients without pain and patients with protracted postoperative pain showed a smaller fat-free muscle CSA of the MF at all levels examined, a smaller fat- free muscle CSA of the LES at the L3 level, and more fat in the PS in patients with pain. The level of operation was not found to be of importance. The present results suggest a general lumbar muscle dysfunction in the pain group, in particular of the deep stabilizing muscle system.

Moyamoya disease as a possible cause of neurological impairment following liver transplantation for Wilson's disease.

In Wilson's disease, liver transplantation can constitute the only option for patients presenting with fulminant hepatic failure or decompensated liver disease unresponsive to drug therapy. We report the case of a 29-year-old woman receiving a liver transplant for end-stage Wilson's disease who developed neurological complications after transplantation. After an accurate evaluation of possible differential causes of neurological complications developing as the result of liver transplantation, moyamoya disease was diagnosed. Moyamoya disease is a rare cerebrovascular disease of unknown etiology. However, data exist supporting a possible role for some immunosuppressive regimens in determining the peculiar vascular alterations observed in moyamoya disease. To the best of our knowledge, the association with post-transplantation state for Wilson's disease has not been previously described.

Accessory appendages of the left atrium as seen during 64-slice coronary CT angiography.

PURPOSE: To document the frequency and variations in number and anatomical shape of accessory appendages of the left atrium as seen on 64-slice cardiac CT. METHODS AND MATERIALS: Retrospective review of the anatomy of the left atrium as depicted by cardiac CT using the acquisition protocol designed for coronary CT Angiography and performed in 166 patients over a 6-month period with a 64-slice ECG-gated CT scanner (Siemens Medical Solutions). The local IRB provided a waiver of informed consent for this retrospective study. Structures less than 5 mm in shape were excluded, as well as large accessory pulmonary veins. RESULTS: Seventeen (17) of 166 patients (10%) had 18 accessory left atrial appendages (only one patient had two). Fifteen (15) accessory appendages were located along the right upper atrial wall and measured 0.9 x 0.6 x 0.5 cm(3) +/- 0.2 x 0.2 x 0.1 (Type 1). Three (3) were located along the left lower atrial wall, and were larger (0.9-2.5 cm cross-section) (Type 2). The right upper accessory appendages were mostly shaped like small diverticuli and the left lower ones were shaped like flat cauliflower expansions. CONCLUSIONS: Accessory left atrial appendages were visualized in 10% of 166 patients during 64-slice coronary CT angiography.

Caseous calcification of the mitral annulus imaged with 64-slice multidetector CT and magnetic resonance imaging.

Caseous calcification of the mitral annulus is a rare entity in cardiac imaging. We present CT and magnetic resonance imaging (MRI) in a patient evaluated for severe mitral valve regurgitation with such calcified cardiac mass in the thickened basal wall of the left ventricle. Despite good visualization of the mass both with 64-slice multidetector CT and MRI, the characterization of the lesion was difficult. The most critical finding was the presence of a hyperdense mass with an even denser peripheral rim on pre-contrast CT images. The mass did not enhance after X-ray contrast agent administration. We discuss the preoperative differential for calcified intramyocardial mass.