A. Munoz del Rio

Estimation of shear wave speed in the human uterine cervix.

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.

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 ≥126 mg/dL, confirmed on a subsequent measurement or treatment with insulin or oral hypoglycemic agent for ≥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 A1c, (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.

CSF Flow through the Upper Cervical Spinal Canal in Chiari I Malformation

BACKGROUND AND PURPOSE: Previous studies have quantified CSF flow in patients with Chiari I at the foramen magnum with single-axial or single-sagittal PCMR. The goal of this study was to measure CSF velocities at multiple cervical spinal levels in patients with Chiari I malformation. MATERIALS AND METHODS: In a patient registry, consecutive patients without surgery who had PCMR flow images in 5–8 axial planes between the foramen magnum and C4 were identified. Four contiguous regions were defined from the foramen magnum to C4. In each region, the fastest positive flow (PSV) and fastest negative flow (PDV) were tabulated. Changes in peak velocity by cervical spinal level and age and sex were tested for significance with linear mixed-effects models. RESULTS: In 17 patients studied, PSV increased progressively and significantly from the foramen magnum to C4. PDVs increased slightly from the foramen magnum to C3. The changes in velocity over the 4 regions tended to be smaller in the 13 patients with tonsilar ectopia than in the 4 patients without it. Age and sex had an effect on peak velocities. CONCLUSIONS: Peak diastolic and systolic CSF velocities are significantly greater below than at the foramen magnum.

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

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.

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 R2. 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 R2 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.

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.

Tapering of the Cervical Spinal Canal in Patients with Scoliosis with and without the Chiari I Malformation

BACKGROUND: Cervical spinal canal tapering may increase CSF velocities and pressures. One report suggests that the cervical spinal canal tapers more steeply in patients with Chiari I than in healthy subjects. The goal of this study was to test the conclusion by measuring spinal canal tapering in another cohort of patients. MATERIALS AND METHODS: Consecutive patients with scoliosis and MR imaging were selected. The MR images were evaluated for tonsillar herniation and syringomyelia. On a midline T2-weighted MR image, the anteroposterior diameter of the spinal canal was measured at each cervical level, and a linear trend line was fit by least-squares regression. The slope of this line was recorded as the taper ratio in millimeters/level. Patients with >5 mm of tonsillar herniation (with or without syrinx) were compared with those without tonsillar herniation (with or without syrinx). Differences in taper ratios for the 2 groups were tested for significance by the Kruskal-Willis test with significance set at .05. RESULTS: Fifty-four patients with scoliosis were identified; 22 had a Chiari malformation and 32 did not. Syringomyelia was identified in 20 of the patients with Chiari and in 8 of the others. The taper ratios averaged −0.9 mm/level for the patients with a Chiari malformation (with or without a syrinx) and −0.4 mm/level for those without it, significant at P = .035. Syringomyelia did not substantially alter the taper ratio in either group. CONCLUSIONS: Patients with scoliosis with a Chiari malformation have more steeply tapering cervical spinal canals than those without it.

Pulmonary perfusion MRI using interleaved variable density sampling and HighlY constrained cartesian reconstruction (HYCR).

To demonstrate the feasibility of performing single breathhold, noncardiac gated, ultrafast, high spatial‐temporal resolution whole chest MR pulmonary perfusion imaging in humans.

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.

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 McNemars 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.