To compare quantitative and subjective image quality and radiation dose between standard computed tomographic (CT) pulmonary angiography (CTPA) and CTPA with a dual-energy technique with reduced iodine load.This prospective study was approved by the institutional review board and each participant provided informed consent. Ninety-four patients (59% male; mean age ± standard deviation, 62 years ± 15) were randomized to one of two protocols: standard CTPA (100-120 kVp) with standard contrast medium injection (n = 46) and dual-energy CTPA (image reconstruction at 50 keV) with the same injection volume as in the standard protocol but composed of contrast medium and saline in a 1:1 fashion, resulting in 50% reduction in iodine load (n = 48). Signal intensity and noise in three central and two segmental pulmonary arteries were measured; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. A five-point scale was used to subjectively evaluate vascular enhancement and image noise. The proportion of diagnostic (score, ≥ 3) studies and the interreader agreement regarding the dichotomized diagnostic versus nondiagnostic scale were compared between the two groups.Compared with standard CTPA, dual-energy CTPA demonstrated higher signal intensity in all pulmonary arteries (all P < .01), inferior noise only in segmental arteries (P < .05), higher SNR and CNR (both P < .05), and compatible effective dose (P > .05). The five-point score was higher in the standard CTPA protocol (P < .05). The interreader agreement regarding the dichotomized diagnostic versus nondiagnostic scale was similar (P > .05) between the two groups.Dual-energy CTPA with image reconstruction at 50 keV allows a significant reduction in iodine load while improving intravascular signal intensity, maintaining SNR and with comparable radiation dose.
The purpose of this study is to compare three CT image reconstruction algorithms for liver lesion detection and appearance, subjective lesion conspicuity, and measured noise.Thirty-six patients with known liver lesions were scanned with a routine clinical three-phase CT protocol using a weight-based noise index of 30 or 36. Image data from each phase were reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR). Randomized images were presented to two independent blinded reviewers to detect and categorize the appearance of lesions and to score lesion conspicuity. Lesion size, lesion density (in Hounsfield units), adjacent liver density (in Hounsfield units), and image noise were measured. Two different unblinded truth readers established the number, appearance, and location of lesions.Fifty-one focal lesions were detected by truth readers. For blinded reviewers compared with truth readers, there was no difference for lesion detection among the reconstruction algorithms. Lesion appearance was statistically the same among the three reconstructions. Although one reviewer scored lesions as being more conspicuous with MBIR, the other scored them the same. There was significantly less background noise in air with MBIR (mean [± SD], 2.1 ± 1.4 HU) than with ASIR (8.9 ± 1.9 HU; p < 0.001) or FBP (10.6 ± 2.6 HU; p < 0.001). Mean lesion contrast-to-noise ratio was statistically significantly higher for MBIR (34.4 ± 29.1) than for ASIR (6.5 ± 4.9; p < 0.001) or FBP (6.3 ± 6.0; p < 0.001).In routine-dose clinical CT of the liver, MBIR resulted in comparable lesion detection, lesion characterization, and subjective lesion conspicuity, but significantly lower background noise and higher contrast-to-noise ratio compared with ASIR or FBP. This finding suggests that further investigation of the use of MBIR to enable dose reduction in liver CT is warranted.
Cardiac angiosarcoma is the most common of the cardiac sarcomas. It can infiltrate into adjacent structures in addition to seeding distant metastases. Coronary artery encasement is a rare but potentially life-threatening complication of cardiac angiosarcoma. We report a case of cardiac angiosarcoma encasing the right coronary artery with subsequent pseudoaneurysm formation with mural thrombus. Magnetic resonance first-pass, contrast-enhanced images are very useful for defining the communication between such lesions and underlying cardiac chambers. In the presence of distant metastases, there are limited treatment options. No intervention was attempted for the pseudoaneurysm, and thus far (12 mo) it has been stable.
Dual-Energy CT Urography With 50% Reduced Iodine Dose Versus Single-Energy CT Urography With Standard Iodine DoseWilliam P. Shuman1, Achille Mileto1, Janet M. Busey1, Nitin Desai1 and Kent M. Koprowicz1Audio Available | Share
Radiologic detection of bone lesions from malignant melanoma is reported to be uncommon or infrequent. To ascertain the characteristics and frequency of detection of melanoma metastases to the axial skeleton by CT, we retrospectively reviewed 464 body CT studies of 125 consecutive melanoma patients for presence, appearance, and site of skeletal metastases. Results were correlated with patient's age, sex, clinical course, and both the Clark and Breslow classifications of the primary lesion. Of 98 patients with metastatic disease evident on their CT studies, 17 (17%) had bony metastases; two (12%) of these 17 patients had skeletal lesions as the only CT evidence of metastatic disease. Metastatic bony lesions were predominantly osteolytic, slightly expansile, and commonly located in the spine. Associated soft-tissue masses were frequent, but periosteal reaction and identifiable tumor matrix were not seen. Skeletal metastases were found only in those patients with thick or intermediate primary melanoma (Breslow) classified as Clark level III or greater, and the CT demonstration of osseous metastases was a poor prognostic sign. The data suggest that CT detection of skeletal melanoma metastases is not uncommon. When CT is performed to evaluate for metastatic melanoma, the axial skeleton should be carefully examined, especially in those patients with more advanced primary lesions.
The Japanese-American population of King County, Washington, is known to have a high prevalence of non-insulin-dependent diabetes mellitus (NIDDM). As part of a community-based study, we reexamined 146 second-generation Japanese-American men who had been initially classified as nondiabetic. At a mean follow-up period of 30 mo, 15 men had developed NIDDM, and 131 remained nondiabetic. The variables measured at the initial visit that distinguished the 15 diabetic men from the 131 nondiabetic men were older age, higher serum glucose level at 2 h after 75 g oral glucose, higher fasting plasma C-peptide level, and increased cross-sectional intra-abdominal fat area as determined by computed tomography. Both older age and higher 2-h glucose levels are variables that have been associated with the development of NIDDM, but the association of higher fasting C-peptide level and greater intra-abdominal fat area with subsequent development of NIDDM were new observations. The elevated fasting C-peptide level persisted after adjustment for fasting serum glucose. The elevated C-peptide level represents hypersecretion of insulin and was interpreted to reflect a compensatory response to an underlying insulin-resistant state that antedates the development of NIDDM. The fasting C-peptide level was correlated with the intra-abdominal fat area, suggesting that the intra-abdominal fat area may be associated with insulin resistance. Thus, in individuals who develop NIDDM, insulin resistance, increased insulin secretion, and increased intra-abdominal fat are present before diabetic glucose tolerance can be demonstrated.
