Automatic image registration of three-dimensional images of the head of cats and dogs by use of maximization of mutual information

Effect of ventral slot procedure on spinal cord compression in dogs with single static intervertebral disc disease: preliminary findings while evaluating a semiquantitative computed tomographic myelographic score of spinal cord compression

OBJECTIVE

To (1) evaluate pre- and postoperative cervical spinal cord compression (SCC) in the context of uncomplicated ventral slot (VS) decompression using computed tomographic (CT) myelography and (2) report reliability of a semiquantitative SCC score using CT myelography.

STUDY DESIGN

Prospective and retrospective, clinical pilot study.

ANIMALS

Dogs (n = 17) with single static intervertebral disc disease.

METHODS

On matched pre- and postoperative transverse CT myelographic images, degree and lateralization of extradural SCC were scored by 4 blinded independent observers, followed by consensus finding. Inter- and intraobserver variability was quantified using intraclass correlation (ICC). Nonparametric tests were performed comparing pre- and postoperative SCC, correlation with neurologic status and significance of lateralization.

RESULTS

Because of invisible contrast agent, only 13 dogs could be fully evaluated. After VS, SCC was significantly reduced whereas neurologic function significantly improved. Ten dogs had residual compression, not affecting neurologic long-term outcome. Only preoperative compression score and neurologic status 3-7 weeks postoperatively were inversely correlated. Lateralization of SCC preoperatively did not affect postsurgical compression scores. Interobserver ICC was 0.848 and intraobserver ICC was 0.984.

CONCLUSIONS

VS improves neurologic function but often fails at completely resolving extradural SCC. The proposed CT myelographic score is highly reliable, assuring consistency among and within observers.

Taxotere chemosensitivity evaluation in mice prostate tumor: validation and diagnostic accuracy of quantitative measurement of tumor characteristics by MRI, PET, and histology of mice tumor

Increased PET and MRI image intensities of mouse prostate tumors were correlated with histostaining tumor characteristics. The hypothesis was that increased intracellular sodium microMRI signal intensities and flouro-2-deoxy-glucose utilization by microPET in apoptosis rich regions in tumors were positively correlated as chemosensitivity assay of Taxotere. The PC-3 cancer cell line induced prostate tumor MRI and PET images and histology slices were digitally captured and compared in pre- and post-Taxotere treated tumors. The optimization of inversion recovery MRI parameters was done to generate sodium images of phantom. The (18)FDG biotransformation was optimized to measure PET image intensities. A criterion was developed to evaluate malignancy by histology. For correlation, regression analysis was done using imaging, histology, and immunostaining data from PC3 tumor after 24 and 48 hours post-Taxotere treatment. Apoptosis indices were calculated by histostaining and ss-DNA antibody assay. Sodium MRI and PET signal intensity distributions were comparable at specific locations relatively and measured in tumor tissue regions. In tumors, Taxotere induced an increase in intracellular sodium MRI signal 30% (p<0.001) with decreased tumor size (20%; p<0.001) and micro-PET showed FDG uptake increase 15% (p<0.001) with decreased tumor size (10%; p<0.001) than that of control tumors after 24 hours. Histological features indicated tumor risk (high 'intracellular/extracellular ratio', high mitotic index, and apoptotic index), decreased tumor viability (reduced mitotic figures, reduced diploidy or aneuploidy, and proliferation index) after Taxotere treatment. These features in co-registered intracellular sodium, microPET hypermetabolic, and monoclonal antibody (ss-DNA) sensitive regions showed (% difference > 6%). Apoptosis rich regions showed characteristic nuclei with S phase DNA histogram, appearing brighter on IC-Na images and mild active on PET images (sensitivity=65%; specificity=70%). In conclusion, MRI and PET multimodal imaging may be rapid non-invasive chemosensitivity assay to monitor the drug anticancer effect.

Application of Coregistration for Imaging of Animal Models of Epilepsy

The past decade has seen a surge in the utilization of small animal imaging for epilepsy research. In vivo imaging studies have the potential to provide important insights into the structural and functional correlates of the development and progression of epilepsy in these models. However, the small size of the rodent brain means that anatomic resolution is often relatively poor for many imaging modalities, particularly those providing functional information such as positron emission tomography. Coregistration of these images with those of higher structural resolution, such as MRI, provides an attractive approach to this problem, and also allows correlations between structural and functional imaging data. Image coregistration is commonly utilized in clinical research and practice. However, its application for small animal images has been, to date, relatively under utilized and largely unvalidated. The current review aims to provide an overview of image coregistration methods, particularly for MRI and PET, and their application to imaging of small animal models of epilepsy. Methodological advantages and potential traps are highlighted.

Densitometric analysis of the human first tarsometatarsal joint

The first tarsometatarsal (TMT) joint has a complex role in regulating joint pressure in the midfoot. Despite its importance, there have been only a few studies of the functional morphology and biomechanical function of this joint. Here we report about the densitometric pattern of the subchondral bone layer of the articulating elements of the human first TMT joint. We studied dry bones of the first metatarsal and medial cuneiform bones in 64 human cadavers to establish the pattern of the density distribution and to correlate it with the biomechanical function of the joint. The articular surfaces of both the bones were analyzed planimetrically. Half of the specimens (n=32) were sectioned in the sagittal plane and the other 32 articulations were in the transverse plane. In all the sections, the subchondral bone density of the first TMT joint was measured. We found that in sagittal slices the dorsal area of the lateral parts and intermediate parts in females and the dorsal area of the lateral parts, the medial parts and intermediate parts in males were denser than the plantar area and that its density decreased towards the plantar area. The dorsal parts of transverse slices in males were the densest and its density decreased towards the plantar part. In the dorsal, middle and plantar parts in females in transverse slices, the lateral and intermediate areas were denser than the medial areas (P<0.05). There was no significant difference between the bone densities of females and males.