MR Diffusion Anisotropy Imaging of Spinal Cord Mechanical Compression and Injury on the Rat Model. In Vivo.

The aim of this study was the application of magnetic resonance diffusion anisotropy imaging (MR DAI) for assessment of spinal cord compression (SCC) and injury (SCI) in rats depending on the time course from the moment of injury. Twenty rats were used, divided into three groups (five with no surgical operation, five with laminectomy only and ten with SCI produced using a dynamic weight - drop model). MR DAI was performed four times (1, 24, 48 and 168 hours after surgery) at 4.7 T with diffusion gradients applied parallel and perpendicular to the spine. Diffusion parameters (lADC, tADC and AI) were calculated for defined regions of white and gray matter. Epidural hematoma which appeared after laminectomy compressed spinal cord and caused a decrease of apparent diffusion coefficient (ADC) values in GM and WM. SCI in WM produced a decrease of lADC and increase in tADC. In GM an increase in both lADC and tADC values after SCI was observed. MR DAI will disclose dynamic changes in water diffusion during the first days after spinal cord contusion.

Hydration study of homopolypeptides by (2)H NMR.

Deuteron T(1) and T(2) was studied as a function of hydration in homopolyglycine (PG) and homopolyproline (PP). Water deuteron relaxation rates in PG conform to a hydration model involving two types of primary hydration sites where water is directly bonded to the polymer. Once these sites are filled, additional water only bonds to water molecules at the primary sites and in so doing affect their dynamics. PP exhibits an anomalous T(1) and T(2) hydration dependence which has been interpreted in terms of a cooperative water molecule-PP molecule helical conformational rearrangement which occurs once a certain hydration level is reached. The proposal of a water-PP structure is tested using molecular dynamics simulations.

Analysis of the diffusion weighted MR microscopy data of excised spinal cord of a rat on the basis of the model of restricted diffusion.

Anisotropic diffusion in the excised rat spinal cord saturated with 0.9% saline was investigated using MR microimaging with b-values up to 8000 s/mm2 for different diffusion times. Non-exponential transversal diffusion decay found in white matter (WM) and gray matter (GM) was fitted with 2 components (the "fast" and the "slow"). Significantly smaller non-exponential dependence was found for the longitudinal diffusion in the WM. Obtained results corresponding to restricted diffusion in the range from approximately 2 to approximately 7 microm were correlated with axon diameter distribution in the WM obtained from transmission electron micrographs. It was concluded that observed diffusion anisotropy in the spinal cord might be entirely explained by presence of the slow transversal component, arising from the restricted diffusion. The strict analytical description of the diffusion decay in nervous tissue requires taking into account continuous distribution of the space-scale of the restricting barriers. The simplified two-component analysis may be applicable for visualization of the nervous tissue in clinical practice.

Renal and ureteric trauma: diagnosis and management in Poland.

OBJECTIVE: To analyse retrospectively kidney and ureteric injuries (the former often associated with multiple-organ trauma) and thus optimize diagnostic and treatment methods. PATIENTS AND METHODS: The records and details of kidney and ureteric injures treated between 1995 and 1999 in 61 urological departments in Poland were analysed. RESULTS: In all, 887 kidney injuries were analysed; blunt trauma comprised 97%, with most injuries classified as renal contusion and minor parenchymal damage (687 cases). Intravenous urography was used in 80% of the patients and computed tomography in only 20%. In all, 234 patients (26%) underwent surgery; nephrectomy was the most common surgical treatment, in 170 patients (73% of those undergoing surgery). Complications occurred in 9% of patients after conservative treatment and in 5% after surgery. Of the 452 ureteric injuries, 340 (75%) were iatrogenic, 81 (18%) blunt injuries and 31 (7%) open injuries. Of the iatrogenic injuries 73% occurred during gynaecological procedures, 14% in general surgery and 14% in urological procedures. The most frequent diagnostic method was intravenous urography (244 cases), with retrograde pyelography (98) and ureteric catheterization in 125. The diagnosis was established immediately during surgery in 104 patients. The most frequent surgical treatment was uretero-neocystostomy (213, 47%), the others being a Boari flap (113, 25%), end-to-end anastomosis (92, 20%), reconstruction with an ileal loop (30, 7%) and autotransplantation (four, 1%). CONCLUSION: In Poland, patients with blunt kidney injuries often undergo surgery, with nephrectomy the most frequent procedure. Computed tomography with the intravenous administration of contrast medium should be considered the diagnostic method of choice for kidney injures. Catheterization of the ureters before surgery and an indigocarmine intravenous infusion (to stain the urine) when a ureteric injury is suspected may reduce the rate of iatrogenic injury and improve the rate of intraoperative diagnosis. We suggest catheterizing the ureters in any doubtful case to avoid injury, because prevention is better than treatment.

Treatment of posterior and anterior urethral trauma.

OBJECTIVE: To assess the occurrence and treatment of posterior urethral (most often caused by traffic accidents and comprising half of all cases of urinary tract traumas) and anterior urethral injury (usually iatrogenic during catheterization or cystoscopy, or caused by blunt trauma, e.g. straddle injury or penetrating trauma). PATIENTS AND METHODS: The records and details of patients with posterior and anterior urethral trauma were analysed from 61 urological departments in Poland between 1995 and 1999. RESULTS: During the 5-year period there were 268 cases of posterior and 255 of anterior urethral injury; for the former, most occurred during traffic accidents, and of the latter 206 were iatrogenic (during catheterization or cystoscopy), of which 48 were accompanied by perineal injury. The posterior injuries were isolated or involved many organs, mainly pelvic bones. Both types of injuries were diagnosed using ascending urethrography, voiding cysto-urethrography and urethroscopy/endoscopy. Treatment for posterior injuries included cystostomy alone or cystostomy with abdominal drainage or perineal drainage; some patients also had their urethra reconstructed. The treatment for anterior injuries was conservative in 193 patients and surgical in 62. CONCLUSION: The early detection and appropriate surgical treatment of posterior and anterior urethral injury is crucial for the recovery of urethral function, and avoids many complications.