The Cervical Spinal Canal Tapers Differently in Patients with Chiari I with and without Syringomyelia.

BACKGROUND AND PURPOSE: The cause of syringomyelia in patients with Chiari I remains uncertain. Cervical spine anatomy modifies CSF velocities, flow patterns, and pressure gradients, which may affect the spinal cord. We tested the hypothesis that cervical spinal anatomy differs between Chiari I patients with and without syringomyelia. MATERIALS AND METHODS: We identified consecutive patients with Chiari I at 3 institutions and divided them into groups with and without syringomyelia. Five readers measured anteroposterior cervical spinal diameters, tonsillar herniation, and syrinx dimensions on cervical MR images. Taper ratios for C1-C7, C1-C4, and C4-C7 spinal segments were calculated by linear least squares fitting to the appropriate spinal canal diameters. Mean taper ratios and tonsillar herniation for groups were compared and tested for statistical significance with a Kruskal-Wallis test. Inter- and intrareader agreement and correlations in the data were measured. RESULTS: One hundred fifty patients were included, of which 49 had syringomyelia. C1-C7 taper ratios were smaller and C4-C7 taper ratios greater for patients with syringomyelia than for those without it. C1-C4 taper ratios did not differ significantly between groups. Patients with syringomyelia had, on average, greater tonsillar herniation than those without a syrinx. However, C4-C7 taper ratios were steeper, for all degrees of tonsil herniation, in patients with syringomyelia. Differences among readers did not exceed differences among patient groups. CONCLUSIONS: The tapering of the lower cervical spine may contribute to the development of syringomyelia in patients with Chiari I.

Effect of IV contrast on lumbar trabecular attenuation at routine abdominal CT: correlation with DXA and implications for opportunistic osteoporosis screening.

UNLABELLED: Osteoporosis remains under-diagnosed. Routine abdominal CT can provide opportunistic screening, but the effect of IV contrast is largely unknown. The overall performance for predicting osteoporosis was similar between enhanced and unenhanced scans. Therefore, both non-contrast and contrast-enhanced abdominal CT scans can be employed for opportunistic osteoporosis screening. INTRODUCTION: Osteoporosis is an important yet under-diagnosed public health concern. Lumbar attenuation measurement at routine abdominal CT can provide a simple opportunistic initial screen, but the effect of IV contrast has not been fully evaluated. METHODS: Mean trabecular CT attenuation values (in Hounsfield units, HU) at the L1 vertebral level were measured by oval region-of-interest (ROI) on both the unenhanced and IV-contrast-enhanced CT series in 157 adults (mean age, 62.0). All patients underwent correlative central DXA within 6 months of CT. Based on DXA BMD of the lumbar spine, femoral neck, and total proximal femur: osteoporosis, osteopenia, and normal BMD was present in 33, 77, and 47, respectively. Statistical analysis included Bland-Altman plots and receiver operating characteristic (ROC) curves. RESULTS: Mean difference (±SD) in L1 trabecular attenuation between enhanced and unenhanced CT series was +11.2 HU (±19.2) (95 % CI, 8.16-14.22 HU), an 8 % difference. Intra-patient variation was substantial, but no overall trend in the HU difference was seen according to underlying BMD. ROC area under the curve (AUC) for unenhanced and enhanced CT for diagnosing osteoporosis were similar at 0.818 and 0.830, respectively (p = 0.632). Thresholds for maintaining 90 % specificity for osteoporosis were 90 HU for unenhanced and 102 HU for enhanced CT. Thresholds for maintaining 90 % sensitivity for osteoporosis were 139 HU for unenhanced and 144 HU for enhanced CT. Similar diagnostic performance was seen for diagnosing low BMD (osteoporosis or osteopenia) using higher HU cut-offs. CONCLUSION: Contrast-enhanced CT shows an average increase of 11 HU over the unenhanced series for L1 trabecular attenuation. The overall performance for predicting osteoporosis is similar between the enhanced and unenhanced scans, thus either can be employed for initial opportunistic screening.

Changes in shear wave speed pre- and post-induction of labor: a feasibility study.

OBJECTIVE: To explore the feasibility of using shear wave speed (SWS) estimates to detect differences in cervical softening pre- and post-ripening in women undergoing induction of labor. METHODS: Subjects at 37-41 weeks' gestation undergoing cervical ripening before induction of labor were recruited (n = 20). Examinations, performed prior to administration of misoprostol and 4 h later included Bishop score, transvaginal ultrasound measurement of cervical length, and 10 replicate SWS measurements using an ultrasound system equipped with a prototype transducer (128 element, 3 mm diameter, 14 mm aperture) attached to the clinician's hand. Subjects were divided into two groups, 'not-in-labor' and 'marked-progression', based on cervical evaluation at the second examination. Measurements were compared via individual paired hypotheses tests and using a linear mixed model, with the latter also used to compare groups. Spearman's rank correlation coefficient was used to compare SWS with Bishop score. The linear mixed model can take into account clustered data and accommodate multiple predictors simultaneously. RESULTS: The Wilcoxon signed-rank paired test established a significant difference in pre- and post-ripening SWS, with mean SWS estimates of 2.53 ± 0.75 and 1.54 ± 0.31 m/s, respectively (P < 0.001) in the not-in-labor group (decrease in stiffness) and 1.58 ± 0.33 and 2.35 ± 0.65 m/s for the marked-progression group (increase in stiffness). The linear mixed model corroborated significant differences in pre- and post-ripening measurements in individual subjects (P < 0.001) as well as between groups (P < 0.0001). SWS estimates were significantly correlated with digitally-assessed cervical softness and marginally correlated with Bishop score as assessed by Spearman's rank correlation coefficient. CONCLUSIONS: In-vivo SWS estimates detected stiffness differences before and after misoprostol-induced softening in term pregnancies. This ultrasonic shear elasticity imaging technique shows promise for assessing cervical softness.

Intra-individual comparison of magnesium citrate and sodium phosphate for bowel preparation at CT colonography: automated volumetric analysis of residual fluid for quality assessment.

AIM: To perform an objective, intra-individual comparison of residual colonic fluid volume and attenuation associated with the current front-line laxative magnesium citrate (MgC) versus the former front-line laxative sodium phosphate (NaP) at CT colonography (CTC). MATERIALS AND METHODS: This retrospective Health Insurance and Portability and Accountability Act-compliant study had institutional review board approval; informed consent was waived. The study cohort included 250 asymptomatic adults (mean age at index 56.1 years; 124 male/126 female) who underwent CTC screening twice over a 5 year interval. Colon catharsis at initial and follow-up screening employed single-dose NaP and double-dose MgC, respectively, allowing for intra-patient comparison. Automated volumetric analysis of residual colonic fluid volume and attenuation was performed on all 500 CTC studies. Colonic fluid volume <200 ml and mean attenuation between 300-900 HU were considered optimal. Paired t-test and McNemar's test were used to compare differences. RESULTS: Residual fluid volumes <200 ml were recorded in 192 examinations (76.8%) following MgC and in 204 examinations (81.6%) following NaP (p = 0.23). The mean total residual fluid volume was 155 ± 114 ml for MgC and 143 ± 100 ml for NaP (p = 0.01). The attenuation range of 300-900 HU was significantly more frequent for MgC (n = 220, 88%) than for NaP (n = 127, 50.8%; p < 0.001). Mean fluid attenuation was significantly lower for MgC (700 ± 165 HU) than for NaP (878 ± 155 HU; p < 0.001). Concomitant presence of both optimal fluid volume and attenuation was significantly more frequent for MgC 65.2% than for NaP (38%; p < 0.001). CONCLUSIONS: Objective intra-individual comparison using automated volumetric analysis suggests that the replacement of NaP by MgC as the front-line laxative for CTC has not compromised overall examination quality.

Estimation of shear wave speed in the human uterine cervix.

OBJECTIVES: To explore spatial variability within the cervix and the sensitivity of shear wave speed (SWS) to assess softness/stiffness differences in ripened (softened) vs unripened tissue. METHODS: We obtained SWS estimates from hysterectomy specimens (n = 22), a subset of which were ripened (n = 13). Multiple measurements were made longitudinally along the cervical canal on both the anterior and posterior sides of the cervix. Statistical tests of differences in the proximal vs distal, anterior vs posterior and ripened vs unripened cervix were performed with individual two-sample t-tests and a linear mixed model. RESULTS: Estimates of SWS increase monotonically from distal to proximal longitudinally along the cervix, they vary in the anterior compared to the posterior cervix and they are significantly different in ripened vs unripened cervical tissue. Specifically, the mid position SWS estimates for the unripened group were 3.45 ± 0.95 m/s (anterior; mean ± SD) and 3.56 ± 0.92 m/s (posterior), and 2.11 ± 0.45 m/s (anterior) and 2.68 ± 0.57 m/s (posterior) for the ripened group (P < 0.001). CONCLUSIONS: We propose that SWS estimation may be a valuable research and, ultimately, diagnostic tool for objective quantification of cervical stiffness/softness.

Tapering of the cervical spinal canal in patients with Chiari I malformations.

BACKGROUND AND PURPOSE: Upper cervical spinal canal dimension may have a role in abnormal CSF dynamics in patients with Chiari I malformation. We attempted to measure spinal canal tapering from anteroposterior spinal canal dimensions in patients with Chiari I. MATERIALS AND METHODS: Twenty-one patients with Chiari I malformation, including 12 with syringomyelia and 7 patients with IS were identified from a local registry. Age- and sex-matched control subjects with cervical spine MR imaging findings reported as normal were selected from the PACS. The anteroposterior diameter of the spinal canal was measured at C1-C7 on T2-weighted sagittal MR images. The taper ratio of the spinal canal was calculated with the regression line. Goodness of fit was calculated as R(2). Differences between patients with Chiari I and other patients were tested for significance with Kruskal-Wallis tests and multivariate analysis. RESULTS: Taper ratios averaged -0.6 ± 0.3 mm/level in the patients with Chiari and syrinx, -0.4 ± 0.2 mm/level (mean ± 1 SD) in the patients with Chiari without syrinx, and -0.3 ± 0.5 mm/level in the patients with IS; control groups had average taper ratios of -0.3 ± 0.2 mm/level. Mean R(2) equaled 0.43. Taper ratios in patients with Chiari and syringomyelia differed significantly from those in the control group (P = .003). Taper ratios in the patients with Chiari without syrinx and in patients with IS did not differ significantly from their matched control groups (P = .60 and 0.76, respectively). CONCLUSIONS: Patients with Chiari I and a syrinx have steeper tapering of the upper cervical spinal canal than matched controls.

Incidence of and risk factors for posttransplant diabetes mellitus after pancreas transplantation.

Posttransplant diabetes mellitus (PTDM) after pancreas transplantation (PTX) has not been extensively examined. This single center, retrospective analysis of 674 recipients from 1994 to 2005 examines the incidence of and risk factors for PTDM after PTX. PTDM was defined by fasting plasma glucose level > or =126 mg/dL, confirmed on a subsequent measurement or treatment with insulin or oral hypoglycemic agent for > or =30 days. The incidence of PTDM was 14%, 17% and 25% at 3, 5 and 10 years after PTX, respectively and was higher (p = 0.01) in solitary pancreas (PAN) versus simultaneous kidney pancreas (SPK) recipients (mean follow-up 6.5 years). In multivariate analysis, factors associated with PTDM were: older donor age (hazard ratio [HR] 1.04, 95% confidence interval [CI] 1.03-1.06, p < 0.001), higher recipient body mass index (HR 1.07,CI 1.01-1.13, p = 0.01), donor positive/recipient negative CMV status (HR 1.65,CI 1.03-2.6, p = 0.04), posttransplant weight gain (HR 4.7,CI 1.95-11.1, p < 0.001), pancreas rejection (HR 1.94.CI 1.3-2.9, p < 0.001) and 6 month fasting glucose (HR 1.01,CI 1.01-1.02, p < 0.001), hemoglobin A(1)c, (HR 1.12,CI 1.05-1.22, p = 0.002) and triglyceride to high-density lipoprotein (TG/HDL) ratio (HR 0.94,CI 0.91-0.96, p < 0.001). This study delineates the incidence and identifies risk factors for PTDM after PTX.

Kidney function after solitary pancreas transplantation.

Preserving kidney function in patients after solitary pancreas transplantation (SPTx) is an important consideration, yet various factors may negatively impact long-term function of the native kidneys or kidney allograft. To determine changes in kidney function over time in a series of patients receiving SPTx, we conducted a retrospective analysis and tracked changes in serum creatinine (SCr) and calculated glomerular filtration rate (GFR) from baseline to 6 months, 1 year, or 3 years after SPTx in a series of pancreas after kidney transplants PAK; (n = 61) and pancreas transplants alone PTA; (n = 27) performed at our institution. The mean follow-up for the PAK and PTA groups was 3.4 and 2.7 years, respectively. In this series, 8% of patients after SPTx developed significant kidney failure, defined by either initiation of dialysis or receiving a kidney transplant (PAK-6, PTA-1). Twenty seven percent of SPTx patients with a baseline GFR < 60 suffered either an elevated SCr > 2.2, dialysis, or kidney transplant, whereas no patients with a baseline GFR > 60 developed significant kidney dysfunction. In the PAK group, the GFR did not show significant deterioration over time. In contrast to relatively stable kidney function in PAK patients, PTA patients experienced overall significantly greater rates of decline over time. GFR in PTA patients decreased from 78 +/- 19 (40 to 114) mL/min/1.73 m2 at baseline to 65 +/- 20 at 1 year (P = .006), while SCr increased from 1.03 +/- 0.25 mg/dL to 1.28 +/- 0.43 over the same time period (P = .012). These data show that kidney function may deteriorate after SPTx and proper patient selection may reduce the frequency of this complication.