MRI in Cirrhotic Patients at High Risk for Hepatocellular Carcinoma

Kim at al reported in JAMA Oncology their experience regarding the accuracy of MRI with liver specific contrast versus ultrasonography in the surveillance of patients with cirrhosis who are at high risk in developing hepatocellular carcinoma.

Ultrasonography (US) is considered the study of choice for screening patients with cirrhosis at risk of hepatocellular carcinoma.  The current recommendation is for US to be performed every 6 months.

Liver MRI was performed on a 1.5Tesla scanner and Gadoxetic acid (Primovist) was administered at a dose of 0.025 mmol/kg.  Axial T1 weighted images of the arterial, portal, delayed and hepatobilliary phases at 4-mm thickness sections were obtained.   

The authors conducted a prospective study of 407 cirrhotic patients who underwent semi-annual US and MRI studies.  The patients were followed with dynamic computed tomography 6 months after the screening imaging studies.

A total of 407 patients received 1100 screenings with both MRI and US.  Hepatocellular carcinomas were diagnosed in 43 patients.  Ultrasound diagnosed only one HCC, MRI detected 26, 11 by both, and 5 were missed by both.

The HCC detection rate of the MRI was 86%, higher than the 27.9% of US.  MRI showed significantly lower false-positive findings than US, 3% versus 5.6% of US.  Of the 43 patients with HCC 32 had a single less than 2 cm nodule and received curative treatments.  The 3-year survival of the patients with HCC (86%) was at par to those without HCC.

The 5-year survival rate of HCC is lower than 20%, and early diagnosis is essential for the possibility of a cure.  The current recommendation for patients at high risk of developing HCC is US needs to be reviewed as the  accuracy of US is low.

The authors conclude that screening of patients with cirrhosis with MRI and liver specific contrast resulted in higher HCC detection rate and fewer false positive findings when compared with US.

JAMA Oncology, Online First, September 22, 2016

Low-Dose Digital Mammography May Be Accurate

Research by Chen et al suggests that low-dose techniques for digital mammography may be feasible, as results are not substantially affected by variations in radiation dose. Their study was published in Radiology.

The researchers analyzed retrospectively a cohort of women from the American College of Radiology Imaging Network Pennsylvania 4006 trial. All patients underwent breast screening with a combination of dose protocols, including standard full-field digital mammography, low-dose digital mammography, and digital breast tomosynthesis. A total of 5832 images from 486 women were analyzed with fully automated software for quantitative estimation of density.

Clinical Breast Imaging Reporting and Data System (BI-RADS) density assessment results were also available from the trial reports. The influence of image acquisition radiation dose on quantitative breast density estimation was investigated with analysis of variance and linear regression.

Radiation dose of image acquisition did not significantly affect quantitative density measurements, with percent density demonstrating a high overall correlation between protocols. However, differences in breast percent density were observed within high BI-RADS density categories, although they were significantly correlated across the different acquisition dose levels.

The authors concluded that reproducibility of automated breast density measurements with digital mammography are not affected by variations in radiation dose; thus, the use of low-dose techniques for the purpose of density estimation may be attainable.

Tailoring Screening Mammography

Research by Trentham-Dietz et al published in the Annals of Internal Medicine recommends that frequency of screening for breast cancer should be based on well-recognized risk factors.

The researchers who were breast-cancer epidemiologists and cancer modelers combined data-collection and conducted simulation modeling using national data for incidence, breast density, and screening performance.

It is an accepted fact that screening benefits and overdiagnosis increase with breast density and relative risk (RR) while false-positive mammograms and benign results on biopsy decrease with increasing risk.

Among women with fatty breasts and an RR of 1.0 or 1.3, breast cancer deaths averted were similar for triennial versus biennial screening for both age groups (50 to 74 years, median of 3.4 to 5.1 vs. 4.1 to 6.5 deaths averted; 65 to 74 years, median of 1.5 to 2.1 vs. 1.8 to 2.6 deaths averted).

Breast cancer deaths averted increased with annual versus biennial screening for women aged 50 to 74 years at all levels of breast density and an RR of 4.0, and those aged 65 to 74 years with heterogeneously or extremely dense breasts and an RR of 4.0. However, harms were almost 2-fold higher.

Triennial screening for the average-risk subgroup and annual screening for the highest-risk subgroup cost less than $100 000 per quality-adjusted life year (QALY) gained which is a value for money of medical interventions.

The authors concluded that average-risk women older than 50 without dense breasts should undergo triennial screening while higher-risk women with very dense breasts should receive annual mammograms.  Such frequency and tailoring of screening mammography will maintain a similar or better balance of benefits and harms than average-risk women receiving annual or biennial screening.

Breast density assessment varies among radiologists

Sprangue et al published in Annals of Internal Medicine the findings of their study that suggests that radiologists often do not agree on what qualifies as dense breast.

The investigators looked at 216,783 mammograms from 145,123 women aged 40 to 89 years that were interpreted by 83 radiologists in 30 radiology facilities in 4 States.

Overall, 36.9% of mammograms were rated as showing dense breasts. Across radiologists, this percentage ranged from 6.3% to 84.5% (median, 38.7%). Examination of patient subgroups revealed that variation in density assessment across radiologists was pervasive in all but the most extreme patient age and BMI combinations. Among women who had consecutive mammograms interpreted by different radiologists, 17.2% (5909 of 34 271) of them suggested different density rating on the two tests.

The authors concluded because there is wide variation in density assessment across radiologists it is a fact should be carefully considered by providers and policymakers when considering supplemental screening strategies.

Colonoscopy vs. CT-Colonography for Detection of High-Risk Polyps

IJspeert et al published in the American Journal of Gastroenterology findings from a randomized trial in which computed tomography colonography (CTC) and colonoscopy were compared for the detection of high-risk sessile serrated polyps (SSP) in average-risk individuals.

Sessile serrated polyps (SSPs) are considered to be the precursors of 15–30% of all colorectal cancers (CRCs). Therefore, CRC screening modalities should be designed to detect high-risk SSPs.

The authors invited 8,844 individuals to join in the trial, of which 1,276 colonoscopy and 982 CTC invitees participated in the study. In the colonoscopy arm, 4.3% of individuals were diagnosed with ≥1 high-risk SSPs, compared with 0.8% in the CTC arm. In total, 3.1% of individuals in the colonoscopy arm were diagnosed with high-risk SSPs as most advanced lesion, compared with 0.4% in the CTC arm.  The current CTC strategy showed a marked lower detection for especially flat high-risk SSPs (17 vs. 0), high-risk SSP located in the proximal colon (32 vs. 1), and SSPs with dysplasia (30 vs. 1).

As sessile serrated polyps are considered precursors of colorectal cancers screening modalities should detect them with high rate of accuracy.  Findings from this trial suggest that the detection rate of high-risk SSPs was significantly higher with colonoscopy than computed tomographic colonography.