MP18-19: Utility of Low Dose Computed Tomography in Obese Patients with Urolithiasis
Friday, May 3, 2024 3:30 PM to 5:30 PM · 2 hr. (US/Central)
302B
Abstract
Information
Full Abstract and Figures
Author Block
Akin S. Amasyali*, Joshua D. Belle, Gabriel E. Martin, Jason Smith, Ala'a Farkouh, D. Duane Baldwin, Loma Linda, CA
Introduction
Obesity is a significant risk factor for both stone formation and recurrence. Obese (BMI >30 kg/m2) patients receiving conventional CT scans are exposed to greater radiation than patients with BMI <30, placing them at increased risk for radiation related complications. Although low dose CT would potentially reduce radiation exposure, it is not commonly utilized in obese patients due to concerns for decreased sensitivity. The purpose of this study was to evaluate the clinical utility of low dose CT scan in obese patients with nephrolithiasis.
Methods
A retrospective review of patients undergoing CT scan for kidney or ureteral stones at a single institution was conducted. Patients were included if their BMI was >30 and they had both a conventional and low dose (LD) CT within 3 months of each other. LD was defined as dose-length product (DLP) <266 mGy*cm (<4 mSv). Those with interval treatment or documented stone passage were excluded. All scans were de-identified and reviewed in a randomized blinded fashion by a board-certified radiologist. Data were collected on radiation exposure, stone presence, location, size, and Hounsfield Units (HU). Paired comparisons were conducted using Wilcoxon signed rank test, with p<0.05 considered significant.
Results
Twenty-six patients met inclusion criteria with BMI ranging from 30.5 to 63.8 kg/m2 (mean 37.3). When compared to conventional CT, 49/55 stones (89% sensitivity) were seen on LD CT (Figure 1). All 6 stones (4 patients) missed on LD CT were =2 mm in size. The mean BMI in these patients where stones were missed on LD CT was 40.2 kg/m2. One false positive or newly formed 2.1 mm stone was identified on a LD CT done 36 days after conventional CT. Stone size on conventional CT ranged from 1 to 26 mm (mean 7.5 mm) with 29 =5 mm and 21 >5 mm. Median difference in stone size between conventional and LD CT was 0.2 mm (p=0.1). The sensitivity for clinically significant stones (>2 mm) was 100%. None of the false negatives or the false positive on LD CT would have altered management.
Conclusions
In our study, low dose CT in patients with BMI >30 kg/m2 accurately identified clinically significant stones while reducing risks associated with radiation exposure. These data suggest that LD CT scan can be considered in non-infected patients with obesity and BMI <40 kg/m2.
Source Of Funding
None
Author Block
Akin S. Amasyali*, Joshua D. Belle, Gabriel E. Martin, Jason Smith, Ala'a Farkouh, D. Duane Baldwin, Loma Linda, CA
Introduction
Obesity is a significant risk factor for both stone formation and recurrence. Obese (BMI >30 kg/m2) patients receiving conventional CT scans are exposed to greater radiation than patients with BMI <30, placing them at increased risk for radiation related complications. Although low dose CT would potentially reduce radiation exposure, it is not commonly utilized in obese patients due to concerns for decreased sensitivity. The purpose of this study was to evaluate the clinical utility of low dose CT scan in obese patients with nephrolithiasis.
Methods
A retrospective review of patients undergoing CT scan for kidney or ureteral stones at a single institution was conducted. Patients were included if their BMI was >30 and they had both a conventional and low dose (LD) CT within 3 months of each other. LD was defined as dose-length product (DLP) <266 mGy*cm (<4 mSv). Those with interval treatment or documented stone passage were excluded. All scans were de-identified and reviewed in a randomized blinded fashion by a board-certified radiologist. Data were collected on radiation exposure, stone presence, location, size, and Hounsfield Units (HU). Paired comparisons were conducted using Wilcoxon signed rank test, with p<0.05 considered significant.
Results
Twenty-six patients met inclusion criteria with BMI ranging from 30.5 to 63.8 kg/m2 (mean 37.3). When compared to conventional CT, 49/55 stones (89% sensitivity) were seen on LD CT (Figure 1). All 6 stones (4 patients) missed on LD CT were =2 mm in size. The mean BMI in these patients where stones were missed on LD CT was 40.2 kg/m2. One false positive or newly formed 2.1 mm stone was identified on a LD CT done 36 days after conventional CT. Stone size on conventional CT ranged from 1 to 26 mm (mean 7.5 mm) with 29 =5 mm and 21 >5 mm. Median difference in stone size between conventional and LD CT was 0.2 mm (p=0.1). The sensitivity for clinically significant stones (>2 mm) was 100%. None of the false negatives or the false positive on LD CT would have altered management.
Conclusions
In our study, low dose CT in patients with BMI >30 kg/m2 accurately identified clinically significant stones while reducing risks associated with radiation exposure. These data suggest that LD CT scan can be considered in non-infected patients with obesity and BMI <40 kg/m2.
Source Of Funding
None
Sessions
MP18: Imaging/Uroradiology I
302B