Precise coordination between nutrient transporters ensures fertility in the malaria mosquito Anopheles gambiae.

Females from many mosquito species feed on blood to acquire nutrients for egg development. The oogenetic cycle has been characterized in the arboviral vector Aedes aegypti, where after a bloodmeal, the lipid transporter lipophorin (Lp) shuttles lipids from the midgut and fat body to the ovaries, and a yolk precursor protein, vitellogenin (Vg), is deposited into the oocyte by receptor-mediated endocytosis. Our understanding of how the roles of these two nutrient transporters are mutually coordinated is however limited in this and other mosquito species. Here, we demonstrate that in the malaria mosquito Anopheles gambiae, Lp and Vg are reciprocally regulated in a timely manner to optimize egg development and ensure fertility. Defective lipid transport via Lp knockdown triggers abortive ovarian follicle development, leading to misregulation of Vg and aberrant yolk granules. Conversely, depletion of Vg causes an upregulation of Lp in the fat body in a manner that appears to be at least partially dependent on target of rapamycin (TOR) signaling, resulting in excess lipid accumulation in the developing follicles. Embryos deposited by Vg-depleted mothers are completely inviable, and are arrested early during development, likely due to severely reduced amino acid levels and protein synthesis. Our findings demonstrate that the mutual regulation of these two nutrient transporters is essential to safeguard fertility by ensuring correct nutrient balance in the developing oocyte, and validate Vg and Lp as two potential candidates for mosquito control.

Interplay between nutrient transporters ensures fertility in the malaria mosquito Anopheles gambiae.

Females from many mosquito species feed on blood to acquire nutrients for egg development. The oogenetic cycle has been characterized in the arboviral vector Aedes aegypti, where after a bloodmeal, the lipid transporter lipophorin (Lp) shuttles lipids from the midgut and fat body to the ovaries, and a yolk precursor protein, vitellogenin (Vg), is deposited into the oocyte by receptor-mediated endocytosis. Our understanding of how the roles of these two nutrient transporters are mutually coordinated is however limited in this and other mosquito species. Here, we demonstrate that in the malaria mosquito Anopheles gambiae, Lp and Vg are reciprocally regulated in a timely manner to optimize egg development and ensure fertility. Defective lipid transport via Lp silencing triggers abortive ovarian follicle development, leading to misregulation of Vg and aberrant yolk granules. Conversely, depletion of Vg causes an upregulation of Lp in the fat body in a manner that appears to be at least partially dependent on target of rapamycin (TOR) signaling, resulting in excess lipid accumulation in the developing follicles. Embryos deposited by Vg-depleted mothers are completely infertile, and are arrested early during development, likely due to severely reduced amino acid levels and protein synthesis. Our findings demonstrate that the mutual regulation of these two nutrient transporters is essential to safeguard fertility by ensuring correct nutrient balance in the developing oocyte, and validate Vg and Lp as two potential candidates for mosquito control.

Selection for insecticide resistance can promote Plasmodium falciparum infection in Anopheles.

Insecticide resistance is under strong selective pressure in Anopheles mosquitoes due to widespread usage of insecticides in vector control strategies. Resistance mechanisms likely cause changes that profoundly affect mosquito physiology, yet it remains poorly understood how selective pressures imposed by insecticides may alter the ability of the mosquito to host and transmit a Plasmodium infection. From pyrethroid-resistant field-derived Anopheles gambiae s.l. mosquitoes, we established resistant (RES) and susceptible (SUS) colonies by either selection for, or loss of insecticide resistance. We show increased oocyst intensity and growth rate as well as increased sporozoite prevalence and intensity in RES compared to SUS females infected with Plasmodium falciparum. The increase in infection intensity in RES females was not associated with the presence of the kdrL1014F mutation and was not impacted by inhibition of Cytochrome P450s. The lipid transporter lipophorin (Lp), which was upregulated in RES compared to SUS, was at least partly implicated in the increased intensity of P. falciparum but not directly involved in the insecticide resistance phenotype. Interestingly, we observed that although P. falciparum infections were not affected when RES females were exposed to permethrin, these females had decreased lipid abundance in the fat body following exposure, pointing to a possible role for lipid mobilization in response to damage caused by insecticide challenge. The finding that selection for insecticide resistance can increase P. falciparum infection intensities and growth rate reinforces the need to assess the overall impact on malaria transmission dynamics caused by selective pressures mosquitoes experience during repeated insecticide challenge.

Targeted Next-Generation Sequencing Analysis of a Pendred Syndrome-Associated Thyroid Carcinoma.

Pendred syndrome is an autosomal recessive disorder characterized by hearing loss and goiter and is caused by bi-allelic mutations (homozygous or compound heterozygous) of the PDS (SLC26A4) gene. The incidence of Pendred syndrome is 7.5-10/100,000 in the general population, and it carries a 1 % risk of developing thyroid carcinoma. Herein, we report a case of a patient with Pendred syndrome who developed a follicular variant of papillary thyroid carcinoma (FVPTC)-that is approximately at an odd of 1/1,000,000. Targeted next-generation sequencing with ThyroSeq v2 was performed on the tumor, and only a TP53 mutation (TP53 p.R175H) was identified. The mutation was limited to the tumor nodule of FVPTC as shown by immunohistochemistry. This report represents the first extensive molecular study of a Pendred syndrome-associated thyroid carcinoma. The evidences support that thyroid carcinomas arising from dyshormonogenetic goiter require additional genetic alteration in addition to the purported thyroid-stimulating hormone (TSH) overstimulation. It is intrigue to note that the mutant p53 is involved in the development of a low-grade malignant thyroid tumor as FVPTC in this patient.

Drug cost implications for antibiotic prophylaxis for dental procedures.

OBJECTIVE: To determine the potential economic impact from the practice of antibiotic prophylaxis for dental procedures. STUDY DESIGN: We estimated the prevalence of patients in the United States with 15 medical conditions and devices. We multiplied the prevalence for each patient population by the percentage of specialists recommending prophylaxis, then by the estimated number of dental office visits per year, and then by an average pharmacy cost to arrive at a total estimated range of annual cost for this practice. RESULTS: The 15 medical conditions and devices included in the present study involve upward of 20 million people and an estimated annual cost between $19,880,279 and $143,685,823. The actual cost may be far greater because of an underestimation of these prevalence figures and the use of antibiotic prophylaxis for additional patient populations. CONCLUSIONS: Our data suggest a significant cost for antibiotic prophylaxis in the dental practice setting and the need for evidence-based recommendations concerning this practice.

Hypoglycemia with intensive insulin therapy after cardiac surgery: predisposing factors and association with mortality.

BACKGROUND: Intensive insulin therapy has become a major therapeutic target in cardiac surgery patients. It has been associated, however, with an increased risk of hypoglycemia compared with conventional insulin therapy. Our study sought to identify the factors predisposing to hypoglycemia with intensive insulin therapy and investigate its effect on early clinical outcomes after cardiac surgery. METHODS: A concurrent cohort study of 2,538 consecutive patients undergoing cardiac surgery (coronary artery bypass grafting, valve, or bypass grafting and valve surgery) from January 2005 to March 2010 was carried out. Multivariable logistic regression analysis and propensity score matching were used (1) to identify the risk factors for developing hypoglycemia (blood glucose < 60 mg/dL) after cardiac surgery and (2) to compare major morbidity, operative mortality, and actuarial survival between patients in whom hypoglycemia developed (n = 77) and those in whom it did not (n = 2461). The propensity score-adjusted sample included 61 patients in whom hypoglycemia developed and 305 patients in whom it did not (1 to 5 matching). RESULTS: Risk factors for hypoglycemia included female gender (odds ratio [OR] = 2.3, 95% confidence intervals [CI] = 1.4-3.7; P < .001), diabetes (OR = 2.8, CI = 1.7-4.5; P < .001), hemodialysis (OR = 3.0, CI = 1.3-6.8; P = .009), intraoperative blood product transfusion (OR = 2.0, CI = 1.2-3.4; P = .010), and earlier date of surgery (years of surgery, 2005-2007; OR = 2.1, CI = 1.2-3.7; P = .007) . Hypoglycemia increased the risk for operative mortality in univariate (hypoglycemic 10% vs normoglycemic patients 2%; P < .001) but not in propensity score- adjusted analysis (OR= 2.5, 0.9-6.7; P = .11). The propensity score-adjusted analysis demonstrated a significant increase in hemorrhage-related reexploration (P = .048), pneumonia (P < .001), reintubation (P < .001), prolonged ventilatory support (P < .001), hospital length of stay (P < .001), and intensive care unit length of stay (P < .001) for the hypoglycemic compared with normoglycemic patients. Five-year actuarial survival was similar in the compared patient groups (hypoglycemic 75% vs normoglycemic 75%; P = .22). CONCLUSIONS: Hypoglycemia with intensive insulin therapy is independently associated with increased risk for respiratory complications and prolonged hospital and intensive care unit lengths of stay after cardiac surgery. In our study, hypoglycemia was not independently associated with increased risk of death.

Magnetic resonance spectroscopy of the cervical cord in amyotrophic lateral sclerosis.

The objective of this study was to use magnetic resonance spectroscopy (MRS) to compare metabolite ratios in the cervical spinal cord of ALS patients to healthy controls. Fourteen ALS patients and 16 controls were scanned using a 3T scanner. A rectangular voxel (8 × 5 × 35 mm) was placed along the main axis of the cord with the lower limit at the inferior aspect of the C2 vertebral body. MRS was performed with a point-resolved spectroscopy (PRESS) sequence. Water signals were suppressed using a three-pulse chemical shift selective (CHESS) saturation sequence. Relative concentrations of choline (Cho), creatine (Cr), myo-inositol (Myo), and NAA were computed from metabolite peaks. Differences in metabolite ratios between ALS patients and controls were assessed with a Wilcoxon rank-sum test. The relationship of metabolite ratios to clinical measures (ALSFRS-R and FVC) was determined by Pearson correlation. The NAA/Cr and NAA/Myo ratios were reduced by 40% and 38%, respectively, in ALS patients. The reduction in NAA/Myo and NAA/Cho correlated significantly with FVC, with correlation coefficients of 0.66 and 0.60, respectively. In conclusion, MR spectra can reliably be obtained from the cervical spinal cord in ALS. MRS of the cervical cord may be a useful biomarker of disease progression.

Prospective study of cervical arthroplasty in 98 patients involved in 1 of 3 separate investigational device exemption studies from a single investigational site with a minimum 2-year follow-up. Clinical article.

OBJECT: Cervical total disc replacement (TDR) was developed to address some of the shortcomings associated with anterior cervical discectomy and fusion (ACDF) by preserving motion at the treated level. To establish an evidence-based rationale for cervical TDR to serve as a viable alternative to ACDF, cervical arthroplasty must establish equivalent or superior clinical outcomes while maintaining motion. The authors report on 98 patients from a single investigational site involved in 3 separate prospective, randomized, controlled investigational device exemption multicenter trials comparing cervical arthroplasty to ACDF with a 2-6-year follow-up. METHODS: Patients with 1- and 2-level cervical disc disease producing radiculopathy and/or myelopathy were randomized prospectively under 3 separate investigational device exemption pivotal trials to undergo ACDF with plate or artificial disc placement. The 3 arthroplasty systems evaluated were the Bryan cervical disc, Kineflex/C disc, and Discover cervical disc. The patients were evaluated with pre- and postoperative serial neurological examinations, radiographs, and clinical outcome indices at 1, 3, 6, 12, 24, 36, 48, and 60 months. RESULTS: Ninety-eight patients were treated at the authors' single investigational site. Fifty-seven of these patients underwent cervical arthroplasty and 41 underwent ACDF. A minimum 24-month follow-up was available for 90 patients (92%; 53 in the combined arthroplasty group and 37 in the combined ACDF group) with a follow-up duration ranging from 24 to 67 months (mean 38 months). Clinical success, defined as a composite measure consisting of 5 separate components, was significantly higher in the combined arthroplasty group (85%) compared with the combined ACDF group (70%; p = 0.035). The Neck Disability Index and visual analog scale patient self-report measures were evaluated at 3-24-months follow-up, and all groups showed excellent clinical outcomes. All groups (Bryan, Kineflex/C, Discover, and ACDF) showed statistically significant improvement from the preoperative period to a minimum 2-year follow-up (p < 0.0001). Overall, angular motion was improved by 0.91° in the combined arthroplasty group and reduced by 7.8° in the combined ACDF group (p < 0.0001). In the ACDF group there was a fusion rate of 97% (36 of 37 cases). In the arthroplasty group there was a 5.6% incidence of bridging heterotopic ossification (3 cases). There were a total of 4 reoperations (7.5%) in the combined arthroplasty group with 1 (1.9%) at the adjacent level. There were 3 reoperations (8.1%) in the ACDF group, all at the adjacent level. CONCLUSIONS: The prospective, intermediate-term (average follow-up > 3 years) results of cervical TDR at the authors' site are encouraging. Patients treated with the artificial discs showed significantly better clinical results, maintained motion at the treated level, and trended toward less adjacent-level disease.

An optimal contrast dose indicator for the determination of hepatic enhancement in abdominal multidetector computed tomography: comparison of patient attenuation indicator with total body weight and body mass index.

PURPOSE: To evaluate a patient attenuation indicator (PAI) as compared with traditional patient-related factors of total body weight and body mass index (BMI) as a predictor of hepatic enhancement in contrast-enhanced abdominal multidetector computed tomography (MDCT). MATERIALS AND METHODS: Institutional review board approval was obtained, and the study was Health Insurance Portability and Accountability Act compliant. A total of 77 patients (mean age, 53 years; male-female ratio, 32:45) underwent routine contrast-enhanced abdominal CT on a 16-slice multidetector CT (LightSpeed 16; GE Medical Systems, Milwaukee, Wis). Contrast enhancement was achieved by administering a 120-mL iodine contrast medium (350-mg iodine per milliliter) at an injection rate of 3 mL/s followed by an injection of 40-mL saline at 3 mL/s. Computed tomographic attenuation values (Hounsfield units [HU]) of liver parenchyma, main portal vein, and abdominal aorta were measured in each patient. Statistical analysis was performed with linear regression to determine the correlation of PAI, total body weight, and BMI with abdominal organ enhancement. RESULTS: The mean of PAI, total body weight, and BMI were 28.0 (range, 22.1-34.2), 79.0 kg (range, 49.6-112.2 kg), and 27.5 kg/m (range, 16.8-43 kg/m), respectively. Mean hepatic enhancement was 128.2 HU (range, 73.6-175 HU), mean main portal vein enhancement was 214.2 HU (range, 118-327 HU), and mean abdominal aorta enhancement was 208.9 HU (range, 116-395 HU). Patient attenuation indicator, total body weight, and BMI showed a negative correlation with liver enhancement (r = -0.55, r = -0.4, and r = -0.3, respectively). Patient attenuation indicator exhibited a significantly higher correlation with hepatic enhancement than total body weight and BMI (P < 0.01, respectively). CONCLUSIONS: Patient attenuation indicator exhibits a moderately inverse correlation with liver enhancement that is greater than those of total body weight and BMI. Patient attenuation indicator may be reliable in predicting the hepatic enhancement degree for a given dose of contrast material and has a potential use in customizing individual patient contrast medium dose during contrast-enhanced abdominal CT.

Posterior bladder layering of excreted 18F-FDG on PET/CT.

PURPOSE: This study was carried out to determine the frequency, characteristics and possible causes and clinical significance of occasionally observed posterior layering of excreted 2-deoxy-2-[F]fluoro-D-glucose (F-FDG) in the bladder. PROCEDURES: A review of 567 consecutive patients referred for positron emission tomography/computerized tomography studies was performed. Urinary bladder size was measured in patients with and without layering. Urine samples from two patients with layering were imaged ex vivo. RESULTS: Twenty-four of 567 studies (4%) showed F-FDG posterior bladder layering. Mean volume+/-SD of the bladder was 175+/-161 ml in patients with layering and 93+/-83 ml in patients without layering. Urine samples collected from two randomly chosen patients with layering in vivo failed to show layering ex vivo. CONCLUSION: Posterior F-FDG layering occurs in 4% of positron emission tomography/computerized tomography cases and highly correlates with bladder volume. The mechanism is hypothesized to be because of slow F-FDG excretion in patients with a distended urinary bladder resulting in delayed mixing with urine, but needs to be further investigated with a more comprehensive study.

Diffusion tensor imaging reveals regional differences in the cervical spinal cord in amyotrophic lateral sclerosis.

Therapeutic development in amyotrophic lateral sclerosis (ALS) is hampered by the lack of suitable biomarkers that might be sensitive to spatial and temporal patterns of neurodegeneration. Diffusion tensor imaging is a useful non-invasive tool that permits detection of microstructural tissue changes due, for example, to neurodegeneration. Even though the spinal cord bears the brunt of the disease process, diffusion tensor imaging has mainly been used to study white matter changes in the brain. The aim of this study was to examine the diffusion tensor imaging parameters of the cervical spinal cord (C1 through C6 segments) and brainstem (corticospinal tracts in the pyramids and pons) among ALS patients, to compare these to findings in age-matched healthy controls, and to correlate these differences with clinical measures of disease severity. Fractional anisotropy in the white matter of the cervical cord was 12% lower (p<0.01) in ALS patients (n=14) compared to age-matched healthy control subjects (n=15), and showed significant positive correlation with the average finger and foot tapping speed (r=0.61, p<0.05) in ALS patients. Radial diffusivity in the cervical cord was 15% higher (p<0.05) in ALS patients compared to healthy control subjects. Radial diffusivity in the white matter of the cervical cord was significantly correlated with clinical measures of disease severity such as forced vital capacity (FVC % predicted, r=-0.69, p<0.01), average finger and foot tapping speed from all four limbs (r=-0.59, p<0.05), and ALSFRS-R (r=-0.55, p<0.05) in ALS patients. There were no significant differences in mean diffusivity or axial diffusivity in the cervical spinal cord, or in any diffusion tensor imaging parameters measured in the brainstem. Analysis of diffusion tensor imaging parameters from individual cervical segments as well as profile plots along the length of the cervical cord showed larger differences in fractional anisotropy and radial diffusivity at more distal cervical segments, providing evidence that supports the "dying-back" hypothesis of neurodegeneration in ALS.

CT-guided liver biopsy: correlation of procedure time and radiation dose with patient size, weight, and lesion volume and depth.

PURPOSE: The purpose of this study was to retrospectively evaluate the effect of various factors, including overall patient size, weight, and individual lesion characteristics, on the radiation dose and procedure time required to successfully perform computed tomography (CT)-guided liver lesion biopsies. MATERIALS AND METHODS: This Institutional-Review-Board-approved study included 209 patients (average age, 59 years; range, 19-86 years; 105 males, 104 females) who underwent CT-guided liver lesion biopsy on a four-slice multidetector row CT scanner (LightSpeed Qx/i; GE Healthcare, Milwaukee, WI). Medical records and images were retrospectively reviewed to obtain the following data: (a) patient weight, (b) patient size, (c) lesion volume, (d) lesion depth, (e) CT dose index (CTDI) and effective radiation dose, and (f) procedure time. Statistical analysis was performed with multiple linear regression to assess the effect of various parameters on radiation dose and procedure time. RESULTS: CTDI was significantly correlated with patient weight (P<.01), size (P=.03), and lesion volume (P<.01). The total effective radiation dose was significantly correlated with patient size (P<.01) and lesion depth (P<.01). Total procedure time was significantly correlated with lesion volume (P<.01) and depth (P<.01). There was a positive correlation between procedure time and effective radiation dose (r(2)=.57). CONCLUSION: In the current study, CT-guided liver lesion biopsy patient radiation dose was associated with both overall patient-specific features (weight and size) and specific lesion characteristics; however, the procedure duration was determined by lesion characteristics (lesion volume and depth) alone.

The effectiveness of locoregional therapies versus supportive care in maintaining survival within the Milan criteria in patients with hepatocellular carcinoma.

PURPOSE: To compare survival after treatment with either locoregional therapy (LRT) or supportive care in patients with hepatocellular carcinoma (HCC) within the Milan criteria. MATERIALS AND METHODS: Patients with HCC who were classified within the Milan criteria (solitary HCC

Adaptive smoothing of high angular resolution diffusion-weighted imaging data by generalized cross-validation improves Q-ball orientation distribution function reconstruction.

Q-ball imaging (QBI) is a high angular resolution diffusion-weighted imaging (HARDI) technique for reconstructing the orientation distribution function (ODF). Some form of smoothing or regularization is typically required in the ODF reconstruction from low signal-to-noise ratio HARDI data. The amount of smoothing or regularization is usually set a priori at the discretion of the investigator. In this article, we apply an adaptive and objective means of smoothing the raw HARDI data using the smoothing splines on the sphere method with generalized cross-validation (GCV) to estimate the diffusivity profile in each voxel. Subsequently, we reconstruct the ODF, from the smoothed data, based on the Funk-Radon transform (FRT) used in QBI. The spline method was applied to both simulated data and in vivo human brain data. Simulated data show that the smoothing splines on the sphere method with GCV smoothing reduces the mean squared error in estimates of the ODF as compared with the standard analytical QBI approach. The human data demonstrate the utility of the method for estimating smooth ODFs.

Utility of axial and radial diffusivity from diffusion tensor MRI as markers of neurodegeneration in amyotrophic lateral sclerosis.

OBJECTIVE: To investigate changes in the diffusion tensor imaging measures, axial diffusivity and radial diffusivity, in addition to the more commonly used fractional anisotropy and mean diffusivity, in patients with amyotrophic lateral sclerosis (ALS) using the voxel-based statistical analysis tool, tract based spatial statistics. METHODS: We studied 12 patients with ALS and 19 normal controls using diffusion tensor imaging; tract based spatial statistics was applied to study changes in fractional anisotropy, mean diffusivity, axial diffusivity and radial diffusivity values in brain white matter tracts. ALS patients were evaluated using clinical examination, administration of the revised ALS functional rating scale and measurement of the forced vital capacity. RESULTS: In ALS patients, we found significant increases in axial diffusivity, radial diffusivity, and mean diffusivity and significant decreases in fractional anisotropy. Increases in axial diffusivity and radial diffusivity were more widespread and more prominent in the corticospinal tract than the decreases in fractional anisotropy. The decreases in fractional anisotropy were evident only in the corona radiata and genu of the corpus callosum. CONCLUSION: In ALS, axial diffusivity and radial diffusivity may be useful diffusion tensor imaging-derived indices to consider in addition to fractional anisotropy and mean diffusivity to aid in demonstrating neurodegenerative changes.

Decreased incidence of NSF in patients on dialysis after changing gadolinium contrast-enhanced MRI protocols.

PURPOSE: To retrospectively determine the incidence of nephrogenic systemic fibrosis (NSF) in patients on dialysis administered either a lower dose high-relaxivity linear gadolinium-chelate, gadobenate dimeglumine (MultiHance, MH), compared to a standard dose linear gadolinium chelate, gadodiamide (Omniscan, OM). MATERIALS AND METHODS: This study was Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board (IRB)-approved. As per institution standardized contrast-enhanced magnetic resonance imaging (MRI) protocols, patients on dialysis were imaged using either MH, between 2/2007 to 9/2008, or OM between 10/2003 and 1/2007. Rates of NSF were compared using 95% score-based confidence intervals (CI). The Wilcoxon rank sum test was used to test similarity/difference between contrast doses given to each patient group. RESULTS: Overall, 312 patients on dialysis received OM and eight (2.6%) developed NSF (95% CI: 1.30%-4.98%). In all, 784 patients on dialysis received MH at a mean cumulative dose of 0.11 mmol/kg (0.05-0.75 mmol/kg) and no cases of NSF were identified (upper 95% confidence bound of 0.45%). The mean cumulative dose of OM was 0.16 mmol/kg (0.1-0.9 mmol/kg) for all patients and 0.28 mmol/kg (0.1-0.8 mmol/kg) for the patients with NSF. The median OM dose was greater in patients who developed NSF (P = 0.03), and was greater than the median MH dose (P < 0.005). CONCLUSION: NSF incidence in at-risk patients receiving contrast-enhanced MRI can be reduced after changing contrast administration protocols that includes changing the type and dose of contrast agent.

Pancreatic adenocarcinoma tumor grade determination using contrast-enhanced magnetic resonance imaging.

OBJECTIVES: To determine whether the degree of enhancement of pancreatic adenocarcinoma visualized on arterial phase gadolinium-enhanced magnetic resonance imaging (MRI) correlates with the histopathological tumor grade. METHODS: Thirty-nine patients with pancreatic adenocarcinoma had MRI within 14 days before tumor resection. Gadolinium-chelate-enhanced (Gd) 3-dimensional gradient echo images were acquired including the arterial phase. Tumor imaging patterns on the arterial phase images were classified for low, moderate, or high degree of enhancement and compared against conventional histological grading. RESULTS: Based on histological grading, there were 12 poorly differentiated, 2 poorly to moderately differentiated, 22 moderately differentiated, and 3 well-differentiated adenocarcinomas. There was agreement between the MRI arterial enhancement pattern and histological grading in 30 of 39 cases. The mean size of tumors grouped by enhancement pattern or grade was not significantly different between groups. Although minor discordance was found in 9 of the 39 cases, statistical analysis showed agreement between the degree of arterial enhancement on MRI and histological tumor differentiation; the Cohen's kappa value was 0.64 with a 95% confidence interval of 0.46-0.83. CONCLUSIONS: Pancreatic adenocarcinoma arterial phase enhancement correlates with the histological grade of differentiation.

Comparison of low-pitch and respiratory-averaged CT protocols for attenuation correction of cardiac PET studies.

PET/CT perfusion studies suffer from artifacts caused by misalignment of transmission and emission data due to contractile cardiac and respiratory motion. This study investigates whether substantial differences exist between two respiration-averaging approaches for attenuation correction (AC): low-pitch helical (HCT) and time-averaged CT (ACT). Fifty-four consecutive patients received paired HCT (0.45 pitch, 120 kVp, 76 mA, 24 x 1.2 mm collimated slice width, 1 s gantry rotation time, 4.93 mGy CTDI) and ACT (sequence mode: 6.1 s acq/bed, 80 kVp, 13 mA, 24 x 1.2 mm collimated slice width, 5.53 mGy CTDI) AC scans under free-breathing prior to Rb-82 rest/adenosine stress. Mismatch between the emission and paired transmission data was compared by calculating the volume of myocardial uptake overlying the left CT lung field. Data were then reconstructed with the CT AC scans and normalized to injected dose and bodyweight. Paired rest and paired stress PET images were reoriented identically along the short axis and sampled into a 17-segment polar map for comparison. The ratio of HCT-PET and ACT-PET polar maps at rest and stress was calculated and grouped by segment for all patients. 95% confidence intervals were calculated to compare changes in the polar map ratios between the two AC methods. No significant difference was observed between the HCT and ACT overlying volume in the rest or stress emission data. 68% of the patients presented visual respiratory artifacts in the HCT images compared to 32% in the ACT. That 23% of the ACT images presented with photon starvation artifacts and increasing BMI was a significant indicator for the occurrence of photon starvation in the ACT AC scans (p < 0.001). The ratio of the reconstructed PET polar segment data showed good agreement between AC methods with 95% confidence intervals ranging from 0.92 to 1.07 in the rest data and 0.93 to 1.07 in the stress data segments. Bias, calculated by averaging the polar segment ratios, showed 1% higher values in the ACT-PET rest reconstructions compared to the HCT-PET rest reconstructions and no measurable bias in the stress reconstructions. This study shows good agreement and negligible bias between low-pitch HCT and ACT protocols for attenuation correction of cardiac PET data.

Lower extremities magnetic resonance angiography with blood pressure cuff compression: quantitative dynamic analysis.

PURPOSE: To quantitatively evaluate changes induced by the application of a femoral blood-pressure cuff (BPC) on run-off magnetic resonance angiography (MRA), which is a method generally previously proposed to reduce venous contamination in the leg. MATERIALS AND METHODS: This study was Health Insurance Portability and Accountability Act (HIPAA)- and Institutional Review Board (IRB)-compliant. We used time-resolved gradient-echo gadolinium (Gd)-enhanced MRA to measure BPC effects on arterial, venous, and soft-tissue enhancement. Seven healthy volunteers (six men) were studied with the BPC applied at the mid-femoral level unilaterally using a 1.5 T MR system after intravenous injection of Gd-BOPTA. Different statistical tools were used such as the Wilcoxon signed rank test and a cubic smoothing spline fit. RESULTS: We found that BPC application induces delayed venous filling (as previously described), but also induces significant decreases in arterial inflow, arterial enhancement, vascular-soft tissue contrast, and delayed peak enhancement (which have not been previously measured). CONCLUSION: The potential benefits from using a BPC for run-off MRA must be balanced against the potential pitfalls, elucidated by our findings.