Detection of Colorectal Hepatic Metastases Is Superior at Standard Radiation Dose CT versus Reduced Dose CT

Abstract

To evaluate colorectal cancer hepatic metastasis detection and characterization between reduced radiation dose (RD) and standard dose (SD) contrast material-enhanced CT of the abdomen and to qualitatively compare between filtered back projection (FBP) and iterative reconstruction algorithms. Materials and Methods:In this prospective study (from May 2017 through November 2017), 52 adults with biopsy-proven colorectal cancer and suspected hepatic metastases at baseline CT underwent two portal venous phase CT scans: SD and RD in the same breath hold. Three radiologists, blinded to examination details, performed detection and characterization of 2-15-mm lesions on the SD FBP and RD adaptive statistical iterative reconstruction (ASIR)-V 60% series images. Readers assessed overall image quality and lesions between SD FBP and seven different iterative reconstructions. Two nonblinded consensus reviewers established the reference standard using the picture archiving and communication system lesion marks of each reader, multiple comparison examinations, and clinical data.Results: RD CT resulted in a mean dose reduction of 54% compared with SD. Of the 260 lesions (233 metastatic, 27 benign), 212 (82%; 95% confidence interval [CI]: 76%, 86%) were detected with RD CT, whereas 252 (97%; 95% CI: 94%, 99%) were detected with SD (P , .001); per-lesion sensitivity was 79% (95% CI: 74%, 84%) and 94% (95% CI: 90%, 96%) (P , .001), respectively. Mean qualitative scores ranked SD images as higher quality than RD series images, and ASIR-V ranked higher than ASIR and Veo 3.0. Conclusion:CT evaluation of colorectal liver metastases is compromised with modest radiation dose reduction, and the use of iterative reconstructions could not maintain observer performance.

Third-generation iterative reconstruction on a dual-source, high-pitch, low-dose chest CT protocol with tin filter for spectral shaping at 100 kV: a study on a small series of COVID-19 patients

“…Baker et al found a significantly higher image quality but degraded detection of low-contrast liver lesions at lower doses and higher strength of IR (SAFIRE, Siemens Healthineers) [ 27 ]. Jensen et al confirmed a lower detection rate of small colorectal liver metastases in low-dose protocols and different IR (ASIR and ASIR-V, GE Healthcare) [ 28 ].…”

Evaluation of Lower-Dose Spiral Head CT for Detection of Intracranial Findings Causing Neurologic Deficits

“…Iterative reconstruction (IR) can provide noninferior performance for high-contrast detection tasks at lower doses; however, recent data in phantoms and abdominal CT suggest that the improvement in observer performance compared with filtered back-projection (FBP) may be limited. [8][9][10][11] Most studies examining lower-dose head CT with iterative reconstruction have relied on subjective comparisons of image quality or contrast-to-noise ratios rather than observer (ie, radiologist) performance. Practical considerations such as collecting cases with proven imaging findings, obtaining CT images at multiple doses, and correlating imaging findings between dose levels and reference standards make such research challenging.…”

“…Mileto et al 9 recently had 16 radiologists examine a low-contrast detectability phantom and found that radiation doses resulted in similar declines in observer performance for FBP and IR and that differences among radiologists were larger than across reconstruction algorithms. Jensen et al 11 found that an approximately 50% dose reduction with one iterative reconstruction approach did not preserve observer performance for the detection of hepatic metastases. Fletcher et al 8,12 found that FBP and IR performed similarly at lower doses in detecting hepatic metastases and that IR might only be needed to maintain observer performance at a certain threshold dose.…”

The eventual rejection of the linear no‐threshold theory will lead to a drastic reduction in the demand for diagnostic medical physics services

“…The race to push radiation doses lower and lower in x‐ray imaging is constant . Both our inboxes and the popular radiology press continually promote the latest “studies” that estimate and extrapolate cancer risks from medical imaging, and the pursuit of the sub‐mSv CT continues despite the demonstrated risks to the patient of using radiation doses that are too low . The rejection of the LNT will end then the need to constantly tweak protocols to reduce radiation doses in pursuit of this white whale.…”