Exposure to ionizing radiation during liver transplantation evaluation, waitlist time, and in the postoperative period: a cause for concern

Radiation exposure from radiological procedures in liver transplant candidates with hepatocellular carcinoma

PURPOSE

Candidates for liver transplantation (LT) with hepatocellular carcinoma (HCC) undergo a large number of diagnostic and interventional radiology procedures. A significant proportion of such procedures involve ionizing radiation with increased lifetime risk of cancer. The objective of our study was to review LT candidates with HCC to quantify ionizing radiation doses from different radiology procedures performed at a single transplant center.

METHOD

We retrospectively reviewed 179 adult patients with HCC (median age 58.6 years [IQR, 55-62]; 155 [86.6%] males) who were accepted for LT between April 2010 and Dec 2018. Radiology procedures and radiation doses were retrieved and the total and median radiation effective dose in millisieverts (mSv) were calculated for different procedures. Exposure to ionizing radiation was categorized based on previously reported thresholds.

RESULTS

We assessed 9,986 radiology procedures for our cohort. Patients had a median effective dose prior to transplantation of 254 mSv (IQR, 130-421) with an annualized rate of 152 mSv (IQR, 92-266). Patient median dose increased to 316 mSv (IQR, 159-478) when including exposures post-LT within the study period. 85% of overall exposure was in the extremely high exposure category (>100 mSv). Interventional procedures represented 13% of procedures with substantial radiation and contributed to 45% of radiation exposure while abdominal CTs represented 39% of total procedures and contributed to 45% of radiation exposure.

CONCLUSIONS

Patients with HCC considered for LT undergo radiology procedures with significant cumulative radiation exposure. Attempts to reduce radiation exposure are suggested by minimizing unnecessary procedures and utilizing ones without ionizing radiation. Improving interventional techniques to reduce radiation doses is needed without compromising treatment delivery.

A nomogram as an indirect method to identify sarcopenia in patients with liver cirrhosis

INTRODUCTION AND OBJECTIVES

Sarcopenia is one of the most common complications of cirrhosis, associated with an increased risk of morbidity and mortality. It is therefore necessary to perform a proper nutritional evaluation in these patients. Although CT scans are the gold standard for diagnosing sarcopenia, they are not widely used in clinical practice. There is thus a need to find indirect methods for identifying sarcopenia in patients with cirrhosis.

MATERIAL AND METHODS

This is a cross-sectional study consecutively including all cirrhotic outpatients who underwent CT scans.

RESULTS

A total of 174 patients met all the inclusion criteria and none of exclusion criteria. Fifty-five patients (31.6%) showed sarcopenia on CT scans. Multivariate analysis revealed that the factors that were independently associated with the presence of sarcopenia on CT scans were: male sex (OR 11.27, 95% CI 3.53-35.95; p<0.001), lower body mass index (BMI) (OR 1.22, 95% CI 1.11-1.34; p<0.001) and lower phase angle by bioelectrical impedance analysis (OR 2.83, 95% CI 1.74-4.6; p<0.001). With the variables identified from the multivariate study we developed a nomogram that allows ruling out the presence of sarcopenia. Our model rules out sarcopenia with an area under the receiver operating characteristic curve value of 0.8. The cutoff point of the probability to rule out sarcopenia was 0.6 (sensitivity 85%, specificity 73%, Youden index 0.58, PPV 82.5% and NPV 91.3%).

CONCLUSION

Since CT scans involve exposure to radiation and their availability is limited, we propose using this nomogram as an indirect method to rule out sarcopenia in cirrhotic patients.

Increasing radiation exposure from computed tomography in liver transplant recipients over time

OBJECTIVES

To evaluate changes in radiation exposure from computed tomography (CT) among patients undergoing liver transplantation in our unit over a 10-year period.

METHODS

We evaluated 134 elective patients, without hepatocellular carcinoma or cholangiocarcinoma who underwent transplantation in 2007-2008 and 2017-2018. CT scans performed in our hospital up to 2 years pre transplant and 1 year post transplant were evaluated.

RESULTS

There was an increase in mean estimated effective radiation dose per patient in 2017-2018 compared to 2007-2008 (77.8 mSv ± 6.2 vs 56.7 mSv ± 5.9, p < 0.05). This change was mainly due to an increased number of pre-transplant CT scans per patient (2.9 ± 0.3 vs 1.4 ± 0.14, p = 0.0001). High radiation dose scan protocols were more frequently used in 2017-2018, with 4-phase liver CT accounting for a larger proportion of scans both pre-transplant (61% vs 43%, p = 0.004) and post-transplant (29% vs 13%, p = 0.002). A greater proportion of patients were exposed to > 100 mSv of ionising radiation in the 2017-2018 patients (29% vs 11%, p < 0.01). These figures are likely to be a significant under-estimate as they exclude other imaging modalities and CT scans performed at other institutions.

CONCLUSION

Radiation exposure from diagnostic imaging has increased among liver transplant recipients at our institution over the last decade. This appears to be due to an increase in the number of CT scans performed, and a shift towards higher dose scan protocols.

Burden of Ionizing Radiation in the Diagnosis and Management of Necrotizing Pancreatitis

INTRODUCTION

A step-up endoscopic or percutaneous approach improves outcomes in necrotizing pancreatitis (NP). However, these require multiple radiographic studies and fluoroscopic procedures, which use low-dose ionizing radiation. The cumulative radiation exposure for treatment of NP has not been well defined.

METHODS

We conducted a retrospective study of consecutive patients with NP admitted to University of California San Francisco Medical Center from January 2011 to June 2019. We calculated effective doses for fluoroscopic procedures using the dose area product and used the National Cancer Institute tool for computed tomography studies. The primary outcome was the cumulative effective dose (CED). Multivariable logistic regression was used to evaluate risk factors of high exposure (CED > 500 mSv).

RESULTS

One hundred seventy-one patients with NP (mean follow-up 40 ± 18 months) underwent a median of 7 (interquartile range [IQR] 5-11) computed tomography scans and 7 (IQR 5-12) fluoroscopic procedures. The median CED was 274 mSv (IQR 177-245) and 30% (51) of patients received high exposure. Risk factors of high exposure include multiorgan failure (aOR 3.47, 95%-CI: 1.53-9.88, P = 0.003), infected necrosis (adjusted odds ratio [aOR] 3.89 95%-CI:1.53-9.88, P = 0.005), and step-up endoscopic approach (aOR 1.86, 95%-CI: 1.41-1.84, P = 0.001) when compared with step-up percutaneous approach.

DISCUSSION

Patients with NP were exposed to a substantial amount of ionizing radiation (257 mSv) as a part of their treatment, and 30% received more than 500 mSv, which corresponds with a 5% increase in lifetime cancer risk. Severity of NP and a step-up endoscopic approach were associated with CED > 500 mSv. Further studies are needed to help develop low-radiation treatment protocols for NP, particularly in patients receiving endoscopic therapy.

CT and MR imaging evaluation of living liver donors

Preoperative cross-sectional imaging evaluation of potential living liver donors allows to exclude donors with an increased risk for morbidity and mortality, and to assure that a suitable graft for the recipient can be obtained, minimizing the risk of complications in both the donor and the recipient. CT is routinely performed to delineate the anatomy of the liver, relevant vasculature, and liver volumes in whole right or left lateral segment donation. MR imaging is the gold standard for the assessment of biliary anatomy and allows a better quantification of hepatic steatosis compared to CT. Knowledge of normal and variant vascular and biliary anatomy and their surgical relevance for liver transplantation is of paramount importance for the radiologist. The purpose of this review is to outline the current role of CT and MR imaging in the assessment of hepatic parenchyma, hepatic vascular anatomy, biliary anatomy, and hepatic volumetry in the potential living liver donor with short notes on acquisition protocols and the relevant reportable findings.

Effective dose for multiple and repeated radiation examinations in donors and recipients of adult-to-adult living donor liver transplants at a single center

PURPOSE

To evaluate the effective doses received by donors and recipients, identify effective dose contributions, and make risk assessments.

MATERIALS AND METHODS

It was a retrospective study. 100 Donors and 100 recipients were enrolled with an operative day from March 2016 to August 2017. The dose was analyzed for all radiation-related examinations over a period of 2 years, 1 year before and 1 year after the LDLT procedure. The effective doses of plain X-rays, CT, fluoroscopy, and nuclear medicine per patient were simulated by a Monte Carlo software, evaluated by the dose-length product conversion factors, evaluated by the dose-area product conversion factors, and evaluated by the activity conversion factors, respectively. The risks of radiation-induced cancer were assessed on the basis of the ICRP risk model.

RESULTS

The median effective doses were 71 (range: 30-186) mSv for donors and 147 (32-423) mSv for recipients. The radiation examinations were mainly performed in the last three months of preoperative period to first month of postoperative period for recipients and donors. The HCC recipients received a higher effective dose, 195 (64-423) mSv, than those with other indications. The median radiation-induced cancer risk was 0.38 % in male and 0.48 % in female donors and was 0.50 % in male and 0.58 % in female recipients.

CONCLUSION

Donors and recipients received a large effective dose, mainly from the CT scans. To reduce effective doses should be included in future challenges in some living donor liver transplants centers that often use CT examinations.

Value of Bone Scans in Work-up of Patients With Hepatocellular Carcinoma for Liver Transplant

Background

The purpose of this study was to review the value of bone scans (BS) in the assessment of bone metastases from early-stage hepatocellular carcinoma (HCC) in patients assessed or waiting for liver transplant (LTx).

Methods

We reviewed BS studies performed at our center for patients with early-stage HCC either being assessed for LTx, or on the waiting list for LTx, from January 2010 to May 2017. The BS findings were classified as positive, equivocal, or negative. Correlation with final outcome based on clinical and radiological follow-up was performed.

Results

There were 360 BS performed in 186 patients during the study period with a mean age of 58.7 years (range, 34.9-70.4 years) and most were male patients (161/186 [86.6%]). None of the BSs resulted in delisting of patients from the LTx waiting list. Three BSs were reported as positive for metastases. All 3 were proven to be false positives on follow-up. Fourteen studies reported equivocal findings, none of which were confirmed to be metastases on follow-up. There was 1 false-negative BS: a bone metastasis was detected incidentally on magnetic resonance imaging and proven on biopsy.

Conclusions

We have demonstrated that the diagnostic yield of BS in early HCC patients who are candidates for LTx is minimal, challenging the current inclusion of BS in guidelines for staging these HCC patients.

A Model to Identify Sarcopenia in Patients With Cirrhosis

BACKGROUND & AIMS

The severe depletion of muscle mass at the third lumbar vertebral level (sarcopenia) is a marker of malnutrition and is independently associated with mortality in patients with cirrhosis. Instead of monitoring sarcopenia by cross-sectional imaging, we investigated whether ultrasound-based measurements of peripheral muscle mass, measures of muscle function, along with nutritional factors, are associated with severe loss of muscle mass.

METHODS

We performed a prospective study of 159 outpatients with cirrhosis (56% male; mean age, 58 ± 10 years; mean model for end-stage liver disease score, 10 ± 3; 60% Child-Pugh class A) evaluated at the Cirrhosis Care Clinic at the University of Alberta Hospital from March 2011 through September 2012. Lumbar skeletal muscle indices were determined by computed tomography or magnetic resonance imaging. We collected clinical data and data on patients' body composition, nutrition, and thigh muscle thickness (using ultrasound analysis). We also measured mid-arm muscle circumference, mid-arm circumference, hand grip, body mass index, and serum level of albumin; patients were evaluated using the subjective global assessment scale. Findings from these analyses were compared with those from cross-sectional imaging, for each sex, using logistic regression analysis.

RESULTS

Based on cross-sectional imaging analysis, 43% of patients had sarcopenia (57% of men and 25% of women). Results from the subjective global assessment, serum level of albumin, and most nutritional factors were significantly associated with sarcopenia. We used multivariate analysis to develop a model to identify patients with sarcopenia, and developed a nomogram based on body mass index and thigh muscle thickness for patients of each sex. Our model identified men with sarcopenia with an area under the receiver operating characteristic curve value of 0.78 and women with sarcopenia with an area under the receiver operating characteristic curve value of 0.89.

CONCLUSIONS

In a prospective study of patients with cirrhosis, we found that the combination of body mass index and thigh muscle thickness (measured by ultrasound) can identify male and female patients with sarcopenia almost as well as cross-sectional imaging (area under the receiver operating characteristic curve values of 0.78 and 0.89, respectively). These factors might be used in screening and routine nutritional monitoring of patients with cirrhosis.

Impact of non-anastomotic biliary strictures after liver transplantation on healthcare consumption, use of ionizing radiation and infectious events

BACKGROUND

Non-anastomotic biliary strictures (NAS) after orthotopic liver transplantation (OLT) have a negative influence on graft survival. Expert opinion suggests a negative effect of NAS on other important aspects of post-transplant care, although its impact is largely unknown as data are scarce.

METHODS

This retrospective single center study analyzed data on healthcare consumption, use of ionizing radiation, infectious complications and development of highly resistant microorganisms (HRMO) in adult patients with NAS. A comparison with a matched control group was made.

RESULTS

Forty-three liver recipients with NAS and 43 controls were included. Hospital admissions were higher in patients with NAS. Most common reason for admission was bacterial cholangitis (BC), with 70% of the patients having at least one episode compared to 9% in the control group. In patients with NAS, 67% received at least one ERCP compared to 21% in the control group (p = 0.001). This resulted in a larger yearly received radiation dose for patients with NAS (p = 0.001). Frequency of intravenous antibiotic therapy was higher (p = 0.001) for patients with NAS, consistently resulting in a higher number of cultures found with HRMO (p = 0.012).

CONCLUSION

NAS after OLT have a negative effect on post-transplant care, increasing readmission rates, interventional procedures, exposure to ionizing radiation, use of antibiotics, and development of HRMO.