Quantitative effects of using compressed sensing in dynamic contrast enhanced MRI

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) involves the acquisition of images before, during and after the injection of a contrast agent. In order to perform quantitative modeling on the resulting signal intensity time course, data must be acquired rapidly, which compromises spatial resolution, signal to noise and/or field of view. One approach that may allow for gains in temporal or spatial resolution or signal to noise of an individual image is to use compressed sensing (CS) MRI. In this study, we demonstrate the accuracy of extracted pharmacokinetic parameters from DCE-MRI data obtained as part of pre-clinical and clinical studies in which fully sampled acquisitions have been retrospectively undersampled by factors of 2, 3 and 4 in Fourier space and then reconstructed with CS. The mean voxel-level concordance correlation coefficient for K(trans) (i.e. the volume transfer constant) obtained from the 2× accelerated and the fully sampled data is 0.92 and 0.90 for mouse and human data, respectively; for 3×, the results are 0.79 and 0.79, respectively; for 4×, the results are 0.64 and 0.70, respectively. The mean error in the tumor mean K(trans) for the mouse and human data at 2× acceleration is 1.8% and -4.2%, respectively; at 3×, 3.6% and -10%, respectively; at 4×, 7.8% and -12%, respectively. These results suggest that CS combined with appropriate reduced acquisitions may be an effective approach to improving image quality in DCE-MRI.     

Paraplegia following the emergency surgical repair of a nonruptured symptomatic abdominal aortic aneurysm: Report of a case

This report presents an extremely rare case of paraplegia following emergency surgery for a nonruptured symptomatic abdominal aortic aneurysm. A 62-year-old man underwent an emergency surgical repair for a symptomatic nonruptured infrarenal abdominal aortic aneurysm. On postoperative day 2 paraplegia following spinal cord ischemia occurred at the T8 level. The site of the ischemia was situated too high for clamping to have caused this condition, unless the patient had a congenital anomaly in the blood supply to the spinal cord or it had been caused by the previously occluded great radicular artery, which was maintained by the collateral blood supply from the iliac circulation.     

Influence of activity level on the outcome of treatment of lateral ankle ligament rupture

Background  Few studies of treatment of lateral ankle ligament rupture have given careful consideration to the activity levels of patients. In the present study, we investigated whether a patient’s activity level influences the outcome of the treatment of lateral ankle ligament rupture and whether treatment should be determined according to activity level. Methods  A total of 115 consecutive patients with lateral ankle ligament rupture were treated with short-term cast immobilization followed by functional bracing. We divided preinjury activity levels and activity levels at follow-up into four classes according to the International Knee Documentation Committee standards. Follow-up examination 1 year after injury included clinical assessment (anterior drawer test, range of motion, maximum circumference of the calf, tenderness, swelling), reinjury assessment, and functional evaluation by means of the Karlsson scoring system. Results  We found significant differences in ankle stability and reinjuries between the four groups classified by their preinjury activity level. The number of patients with ankle instability and reinjury was significantly higher in the high-activity group than in the low-activity groups. We also found significant difference between groups classified by activity level at follow-up with regard to the Karlsson score. Conclusions  The outcome of treatment of lateral ankle ligament rupture is significantly influenced by the patient activity level, and treatment may need to be determined according to this activity level.     

Surgical simulation of circumferential osteotomy and correction of cervico-thoracic kyphoscoliosis for an irreducible old C6–C7 fracture dislocation

Background  Many different surgical procedures have been employed in the treatment of fracture dislocation at the middle to lower cervical spine. However, consistent protocols and procedures have not been fully established for the surgical correction of an irreducible old cervical fracture dislocation associated with spinal deformity. Methods  We report a case of irreducible cervical fracture dislocation and kyphoscoliosis, in which surgical simulation using a three-dimensional full-scale model was useful for circumferential corrective osteotomy at the C6–C7 level. A 56-year-old man was diagnosed with an irreducible fracture dislocation at the C6–C7 level 2 months after a motor vehicle accident. He showed torticollis, and complained of severe pain in his neck and left upper arm. Radiographic examinations revealed that the C6 vertebra was translated anteriorly and laterally to the C7 vertebra. A bony union had progressed at the fracture site, showing rigid cervico-thoracic kyphoscoliosis. To assist in the preoperative planning, we created a three-dimensional, full-scale model from the patient's computed tomography data. Using the model, we performed a simulation of the planned circumferential corrective osteotomy at the C6–C7 level. Results  Through the simulation, we could evaluate the deformed bony structures around the vertebral arteries at the C6–C7 level accurately. At the time of the actual surgery, corrective osteotomy combined with spinal fusion (C5–T2) with a pedicle screw-rod system was accomplished successfully without any neurovascular complications. After surgery, the patient experienced relief from pain, and his neck posture became normal. Conclusions  Surgical simulation using a three-dimensional, full-scale model was useful for improving the accuracy and safety of circumferential corrective osteotomy of the cervical spine.     

Sex Differences in WISC-III Profiles of Children with High-functioning Pervasive Developmental Disorders

Using the Japanese version of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III), 26 girls with high-functioning (IQ ≥ 70) pervasive developmental disorders (HFPDD) (mean age, 8.2 years) were compared with 116 boys with HFPDD (mean age, 9.0 years). Compared with the boys, the girls scored significantly higher on the Processing Speed index, Coding, and Symbol Search, but scored significantly lower on Block Design. Although both groups showed weakness on Comprehension in the verbal domain, the girls’ subtest profile in the performance domain was relatively even and significantly different from the boys’, which was characterized by a peak on Block Design. Such differences should be replicated, and possible behavioral, neurological, and genetic links to these sex differences should be clarified.     

Proteomics of tumor-specific proteins in cerebrospinal fluid of patients with astrocytoma: Usefulness of gelsolin protein

Changes in cerebrospinal fluid (CSF) composition have been shown to accurately reflect pathological processes in the CNS, and are potential indicators of abnormal CNS states, such as tumor growth. To detect biomarkers in high-grade astrocytomas, the differential expression of proteins in the cerebrospinal fluid was analyzed from two cases each of diffuse astrocytoma (grade II), and glioblastoma (grade IV) using agarose 2-D gel electrophoresis (2-DE). It was found that the expression of gelsolin protein decreased with histological grade. To examine whether gelsolin is a useful indicator of tumor aggressiveness or patient outcome, its expression was further studied on immunohistochemistry in 41 formalin-fixed and paraffin-embedded astrocytomas. The positive cell rate of gelsolin in tumors was 59.4% in grade II, 30.0% in grade III and 29.4% in grade IV, respectively. Gelsolin expression was significantly lower in high-grade astrocytomas (grade III or IV) than in low-grade astrocytomas (grade II; P < 0.05). Moreover, in astrocytomas the overall survival of patients in the low-expression group was significantly poorer than in the high expression group ( P < 0.05). These data suggest that gelsolin is a prognostic factor in astrocytoma.     

Automatic detection method of muscle fiber movement as revealed by ultrasound images

The objective of this study was to develop a method of muscle structure measurement based on the automatic analysis of muscle fibers, proximal fascias, and distal aponeurosis movements as revealed by a time-series of ultrasound images. This method was designed to detect changes in the length of muscle fiber movements, and its validity was demonstrated in a time-series of muscle movement, slow ankle dorsiflexion (10°/s), by comparison to manual measurement. The results showed that, when this method was used, the changes in the length of the muscle fiber under slow muscle movement were smaller than those in manual operations by novice individuals. However, with the proposed method, it was possible to obtain a sufficient degree of validity and reliability for the changes in the length of the muscle fiber length compared with those in manual operations, since the correlation coefficients exceeded 0.8 which was tested by the linear regression. The proposed method suggests that automation reduces the errors caused by manual operations and makes the processing of data possible in an acceptable amount of time.     

Low O2 metabolism of HepG2 cells cultured at high density in a 3D microstructured scaffold

Among the features of in vivo liver cells that are rarely mimicked in vitro, especially in microchips, is the very high cell density. In this study, we have cultured HepG2 in a plate-type PDMS scaffold with a three-dimensional ordered microstructure optimally designed to allow cells to attach at a density of 10⁸ cells/mL. After the first step of static open culture, the scaffold was sealed to simulate the in vivo oxygen supply, which is supplied only through the perfusion of medium. The oxygen consumption rate at various flow rates was measured. An average maximal cellular oxygen consumption rate of 3.4 × 10⁻¹⁷ mol/s/cell was found, which is much lower than previously reported values for hepatocytes. Nevertheless, the oxygen concentration in the bulk stream was not the limiting factor. It has been further confirmed by the reported numerical model that the mass transport resistance on the surface of a cell that limits the oxygen supply to the cell. These results further emphasize that access to a sufficient quantity of oxygen, especially through the diffusion-limited layer on the surface of a cell, is very important for the metabolism of hepatocytes at such a high density.