Impact of iterative reconstruction on image quality and radiation dose in multidetector CT of large body size adults

Objective

To compare image quality and radiation dose using Adaptive Statistical Iterative Reconstruction (ASiR) and Filtered Back Projection (FBP) in patients weighing ≥91?kg.

Methods

In this Institution Review Board-approved retrospective study, single-phase contrast-enhanced abdominopelvic CT examinations of 100 adults weighing ≥91?kg (mean body weight: 107.6?±?17.4?kg range: 91–181.9?kg) with (1) ASiR and (2) FBP were reviewed by two readers in a blinded fashion for subjective measures of image quality (using a subjective standardized numerical scale and objective noise) and for radiation exposure. Imaging parameters and radiation dose results of the two techniques were compared within weight and BMI sub-categories.

Results

All examinations were found to be of adequate quality. Both subjective (mean?=?1.4?±?0.5 vs. 1.6?±?0.6, P?P?P?Conclusion In obese individuals, abdominal CT images reconstructed using ASiR provide diagnostic images with reduced image noise at lower radiation dose.

Key Points

? CT images in obese adults are noisy, even with high radiation dose. ? Newer iterative reconstruction techniques have theoretical advantages in obese patients. ? Adaptive statistical iterative reconstruction should reduce image noise and radiation dose. ? This has been proven in abdominopelvic CT images of obese patients.     

Multidetector CT and histological features of benign mesenchymoma of the infratemporal space: a rare case report

Benign mesenchymoma is a soft tissue neoplasm composed of an admixture of two or more benign mesenchymal components in addition to fibrous tissue. A rare case of benign mesenchymoma of the infratemporal space in a 14-year-old boy is presented. In this case report we discuss the salient imaging and histopathological features of this rare entity.     

Nationwide,Longitudinal Trends in CT Colonography Utilization: Cross-Sectional Survey Results From the 2010 and 2015 National Health Interview Survey

PurposeColon cancer screening reduces deaths from colorectal cancer. Screening rates have plateaued; however, studies have found that giving patients a choice between different screening tests improves adherence. CT colonography is a minimally invasive screening test with high sensitivity for colonic polyps (>1 cm). With increasing insurance coverage of CT colonography nationwide, there are limited estimates of CT colonography utilization over time. Our purpose was to estimate CT colonography utilization over time using nationally representative cross-sectional survey data.MethodsWe utilized 2010 and 2015 National Health Interview Survey cross-sectional data. Participants between ages 50 and 75 without colorectal cancer history were included. Accounting for complex survey design elements, logistic regression analyses evaluated changes in CT colonography utilization over time, adjusted for potential confounders, and stratified by insurance and age.ResultsOverall, 21,686 respondents were included (8,965 in 2010, 12,721 in 2015). Reported CT colonography utilization decreased from 1.2% to 0.9% (odds ratio [OR] 0.92, 95% confidence interval [CI] 0.86-0.98). Stratified analyses revealed no changes in utilization in patients with private insurance (P = .35) and in patients younger than 65 (P = .07). Overall awareness of CT colonography decreased from 20.5% to 15.9% (OR 0.93, 95% CI 0.91-0.95). Reported optical colonoscopy utilization increased from 57.9% to 63.6% (OR 1.03, 95% CI 1.02-1.05).ConclusionDespite increasing self-reported utilization of optical colonoscopy from 2010 to 2015, survey results suggest that CT colonography awareness (～16%) and utilization (～1%) remain low. Improved public awareness and coverage expansion to Medicare-aged populations will promote improved CT colonography utilization and overall colorectal cancer screening rates.     

Surgical placement of biologic mesh spacers prior to external beam radiation for retroperitoneal and pelvic tumors

PurposeTo determine the feasibility of surgical placement of biologic mesh spacers to displace bowel and other radiation-sensitive organs prior to external beam radiation for difficult retroperitoneal and pelvic tumors.Methods and MaterialsTumors were resected if possible, and intraoperative electron radiation therapy (IOERT) was directed to the tumor or tumor bed in selected patients. Biologic mesh spacers comprised of cadaveric human skin treated to remove cells and preserve extracellular matrix (Alloderm; Lifecell, Branchburg, NJ) were then placed around the tumor or tumor bed. External radiation techniques included proton beam radiation therapy (PBRT) and intensity modulated radiation therapy (IMRT).ResultsPatients had primary sarcomas (n = 2), radiation-associated sarcomas (n = 1), or isolated metastases (n = 2) in the retroperitoneum or pelvis. One patient received preoperative radiation. Three tumors were marginally resected (R1 resection) while 2 tumors were left in situ, and 3 patients received IOERT (10-17 Gy) to the tumor or tumor bed. Up to 4 sheets of biologic mesh were used as spacers around the tumor or tumor bed to displace small bowel, colon, ureter, bladder, or pancreas. The average distance of the 4 closest organs prior to mesh placement was 1.3-9 mm and after mesh placement was 8.0-23.5 mm. Preoperative or postoperative radiation 36-76 Gy was delivered by IMRT or PBRT. There were no early complications from mesh placement and late complications possibly related to radiation included 1 vertebral body compression fracture and 1 deep vein thrombosis. There were no mesh-related infections and none of the meshes required removal. All 5 patients currently remain free of disease progression after 3-38 months.ConclusionsBiologic mesh spacers can be placed around tumors or tumor beds to displace radiation-sensitive organs and may allow for safer delivery of external beam radiation.     

Impact of low-energy CT imaging on selection of positive oral contrast media concentration

Abdominal Radiology - To determine to what extent low-energy CT imaging affects attenuation of gastrointestinal tract (GIT) opacified with positive oral contrast media (OCM). Second, to establish...     

Gallbladder Lesions Identified on Ultrasound. Lessons from the Last 10?Years

Background

Possible mass lesions identified on ultrasound (US) of the gallbladder may prompt an aggressive surgical intervention due to the possibility of a malignant neoplasm.

Aim

This study aims to utilize a large modern series of patients with gallbladder lesions identified on US to evaluate imaging characteristics consistent with malignancy.

Methods

A retrospective review was conducted of gallbladder ultrasound reports and clinicopathologic data of patients with a mass identified on US.

Results

Approximately 59,271 abdominal ultrasounds and 9,117 cholecystectomies were performed between February 2000 and February 2010. We identified 213 patients with a questionable gallbladder neoplasm on ultrasonography who underwent surgical exploration. Median age was 52?years (range?=?11?C87?years) and 147 (69%) were females. Final pathology demonstrated no neoplasm in 130 patients (61%), while 32 patients (15%) had a wall adenomyoma, 36 (17%) had a polyp (five of which were malignant), 14 (7%) had an adenocarcinoma not arising from a polyp, and one patient had a cystic papillary neoplasm. The smaller the lesion, the more likely it was to be a pseudo-mass. For lesions measuring <5?mm on US, 83% had no lesion found on final pathology. Significant predictors of malignancy were age >52?years (p?p?=?0.004), size >9?mm (p?p?5?mm (p?Conclusions Despite improvements in imaging, most apparent lesions measuring <5?mm on US are not identified in the surgical specimen. US size >9?mm, age >52?years, US suggestion of invasion at the liver interface, and wall thickening >5?mm, especially in the presence of gallstones, should raise the suspicion of malignancy.     

Orthopedic metallic hardware in routine abdomino-pelvic CT scans: occurrence and clinical significance

Abdominal Radiology - To study the occurrence of orthopedic metallic hardware in routine abdomen/pelvic computed tomography (CT) scans and their impact on image quality (IQ) and diagnostic...