Comparison of single CT scan assessment of bone mineral density, vascular calcification and fat mass with standard clinical measurements in renal transplant subjects: the ABC HeART study.

BACKGROUND: Despite limitations of routine methods, Clinical Practice Guidelines support the assessment of bone mineral density (BMD) and vascular calcification in renal transplant recipients. Changes in fat mass also occur post-transplantation, although they are traditionally difficult to measure accurately. We report the feasibility, convenience and accuracy of measuring the above 3 parameters using a novel CT protocol. METHODS: We conducted a cross-sectional study of 64 first renal allograft recipients (eGFR > 30 ml/min/1.73 m(2)). Quantitative CT (QCT) BMD analysis was conducted using CT lumbar spine (GE Medical Systems Lightspeed VCT & Mindways QCT Pro Bone Mineral Densitometry System Version 4.2.3) to calculate spinal volumetric BMD and compared with standard DXA calculated areal BMD at the spine, hip and distal forearm. Abdominal aortic calcification was assessed by semi-quantitative Aortic Calcification Index (ACI) method and compared with lateral lumbar x-ray Kappuila score and pulse wave velocity (PWV). Visceral and subcutaneous adipose tissue volume (Osirix 16 Ver 3.7.1) was compared with BMI. RESULTS: Participants were 61 % male, had a mean age of 47 years, median ESKD duration of 5.4 years and a mean eGFR of 54 ml/min. iDXA median T-score at proximal femur was -1.2 and at lumbar spine was -0.2. Median QCT Trabecular T-score at lumbar spine was -1.2. The percent of subjects with a T-score of < 2.5 by site and method was DXA Proximal Femur: 7 %, DXA distal radius: 17 %, DXA spine: 9 %, QCT (American College of Radiology cutoffs): 9 %. CT derived ACI correlated with PWV (r = 0.29, p = 0.02), pulse wave pressure (r = 0.51, p < 0.001), QCT Trabecular (-0.31, p = 0.01) and cortical volumetric BMD and history of cardiovascular events (Mann-Whitney U, p = 0.02). Both visceral and subcutaneous adipose tissue correlated with BMI (r = 0.63 & 0.64, p < 0.001). CONCLUSIONS: Single CT scan triple assessment of BMD, vascular calcification and body composition is an efficient, accurate and convenient method of risk factor monitoring post renal transplantation.

Diagnostic accuracy of computed tomography using lower doses of radiation for patients with Crohn's disease.

BACKGROUND & AIMS: Magnetic resonance and ultrasonography have increasing roles in the initial diagnosis of Crohn's disease, but computed tomography (CT) with positive oral contrast agents is most frequently used to identify those with acute extramural complications. However, CT involves exposure of patients to radiation. We prospectively compared the diagnostic accuracy of low-dose CT (at a dose comparable to that used to obtain an abdominal radiograph) with conventional-dose CT in patients with active Crohn's disease. METHODS: Low and conventional dose CT of the abdomen and pelvis were acquired from 50 patients with Crohn's disease, referred from an inflammatory bowel disease service (20 male; median age, 34 years). Acute complications of Crohn's disease were suspected. Iterative reconstruction was performed on all CT datasets to facilitate dose reduction. Three radiologists reviewed the low-dose CT images before the conventional-dose CT images. RESULTS: The median effective dose (interquartile range) of radiation for the low-dose CT was reduced by 72% from that of conventional CT: from 3.5 mSv (3-5.08 mSv) to 0.98 mSv (0.77-1.42 mSv) (P < .001). As expected, the quality indexes of the low-dose images were inferior to those of the conventional-dose images, but no clinically significant diagnostic findings were missed with low-dose imaging. Follow-up CT examinations were recommended for 5 patients; 1 had a cervical tumor, 1 had a pancreatic lesion, and 3 had intra-abdominal abscess. In each case, the image obtained by low-dose CT was considered sufficient for diagnosis. CONCLUSIONS: Although low-dose CT images are of lower quality than images obtained with conventional doses of radiation, no clinically significant diagnostic findings were missed from low-dose CT images of patients with Crohn's disease. The low-dose CT was obtained at a median effective dose equivalent to 1.4 abdominal radiographs.

Radiologic imaging in cystic fibrosis: cumulative effective dose and changing trends over 2 decades.

OBJECTIVE: With the increasing life expectancy for patients with cystic fibrosis (CF), and a known predisposition to certain cancers, cumulative radiation exposure from radiologic imaging is of increasing significance. This study explores the estimated cumulative effective radiation dose over a 17-year period from radiologic procedures and changing trends of imaging modalities over this period. METHODS: Estimated cumulative effective dose (CED) from all thoracic and extrathoracic imaging modalities and interventional radiology procedures for both adult and pediatric patients with CF, exclusively attending a nationally designated CF center between 1992-2009 for > 1 year, was determined. The study period was divided into three equal tertiles, and estimated CED attributable to all radiologic procedures was estimated for each tertile. RESULTS: Two hundred thirty patients met inclusion criteria (2,240 person-years of follow-up; 5,596 radiologic procedures). CED was > 75 mSv for one patient (0.43%), 36 patients (15.6%) had a CED between 20 and 75 mSv, 56 patients (24.3%) had a CED between 5 and 20 mSv, and in 138 patients (60%) the CED was estimated to be between 0 and 5 mSv over the study period. The mean annual CED per patient increased consecutively from 0.39 mSv/y to 0.47 mSv/y to 1.67 mSv/y over the tertiles one to three of the study period, respectively (P < .001). Thoracic imaging accounted for 46.9% of the total CED and abdominopelvic imaging accounted for 42.9% of the CED, respectively. There was an associated 5.9-fold increase in the use of all CT scanning per patient (P < .001). CONCLUSIONS: This study highlights the increasing exposure to ionizing radiation to patients with CF as a result of diagnostic imaging, primarily attributable to CT scanning. Increased awareness of CED and strategies to reduce this exposure are needed.