Hepatopulmonary shunting on Tc99m-MAA liver mapping: correlation with dynamic cross-sectional imaging and description of different shunting patterns

Transarterial chemoembolization as an alternative to radioembolization is associated with earlier tumor recurrence than in radioembolization-eligible patients

Introduction

Although transarterial radioembolization (TARE) using yttrium-90 (⁹⁰Y) is a treatment option for large hepatocellular carcinoma (HCC), a fraction of patients are ineligible for TARE due to high lung shunt fraction (LSF).

Methods

We evaluated if treatment with transarterial chemoembolization (TACE), owing to TARE ineligibility was associated with early HCC progression. Consecutive patients with HCC who were initially TARE candidates were included. Patients with vascular invasion or metastasis were excluded. Primary endpoints were time-to-progression (TTP) and overall survival (OS). The secondary endpoint was objective response rate.

Results

In total, 175 patients were included: 144 underwent TARE (TARE-eligible group) and 31 underwent TACE due to high LSF (TARE-ineligible group). This latter group had larger tumors (13.8 cm vs. 7.8 cm, P<0.001) and higher MoRAL scores (1,385.8 vs. 413.3, P=0.002) than the TARE-eligible group. After balancing baseline characteristics with an inverse probability of treatment weighting (IPTW), the TARE-ineligible group showed shorter TTP [adjusted hazard ratio (aHR)=2.16, 95% confidence interval (CI)=1.14-4.07, P=0.02] and OS (aHR=1.80, 95% CI=0.85-3.80, P=0.12), although the latter was not statistically significant. The TARE-ineligible group had a significantly lower objective response rate than the TARE-eligible group (9.7% vs. 56.9%, P<0.001).

Conclusion

TARE-ineligible patients had larger tumors and higher MoRAL scores than TARE-eligible patients. Treatment with TACE, owing to high LSF, was associated with a shorter TTP even after balancing tumor size and MoRAL scores.

Association of dysmorphic intratumoral vessel with high lung shunt fraction in patients with hepatocellular carcinoma

To evaluate the role of dysmorphic intratumoral vessels as imaging marker for the prediction of high lung shunt fraction (LSF) in patients with hepatocellular carcinoma (HCC). This retrospective study included 403 patients with HCC who underwent a planning arteriography for transarterial radioembolization with administration of 99mTc-macroaggregated albumin to calculate LSF. The LSF was measured by using planar body scans. Two radiologists evaluated the pre-treatment contrast-enhanced CT findings, including tumor number, size, margin, distribution, tumor burden, portal and hepatic vein invasion, early hepatic vein enhancement, and dysmorphic intratumoral vessels. The logistic regression analysis was performed to determine significant predictors for high LSF > 20%. Using the identified predictors, diagnostic criteria for high LSF were proposed. Among 403 patients, 52 (13%) patients had high LSF > 20%, and dysmorphic tumor vessels were present in 115 (28.5%) patients. Predictors for LSF > 20% were tumor size > 11 cm, hepatic vein invasion, early hepatic vein enhancement, and dysmorphic intratumoral vessel. If the patient had three or more of the four predictors for LSF > 20% on imaging, the accuracy and specificity for diagnosing LSF > 20% were 88.8% and 96.3% respectively. Dysmorphic intratumoral vessel in HCC is an imaging marker suggesting a high LSF, which may be applicable to treatment modification or patient exclusion for radioembolization with combined interpretation of tumor size and hepatic vein abnormality.

Repeat Evaluation of Lung Shunt Fraction is Unnecessary: A Retrospective Observational Study of Successive Lung Shunt Fractions from Variable Arterial Distributions in Patients Undergoing Radioembolization of Primary and Secondary Liver Tumors

PURPOSE

To evaluate whether the recalculation of lung shunt fraction (LSF) is necessary prior to next-stage or same lobe repeat radioembolization.

MATERIALS AND METHODS

Retrospective chart review was performed for patients who underwent radioembolization between February 2008 and December 2018. Eighty of 312 patients had repeat mapping angiograms and LSF calculations. A total of 160 LSF calculations were made using planar imaging (155, [97%]) and single-photon emission computed tomography (5 [3%]) technetium-99m macroaggregated albumin hepatic arterial injection imaging. The mean patient age was 61.8 years ± 12.7; 69 (86%) patients had metastatic disease and 11 (14%) had hepatocellular carcinoma.

RESULTS

Patients had a median LSF of 5% (interquartile range [IQR] 3%-9%) with a median absolute difference of 1.25 (IQR 0.65-3.4) and a median of 76 days (IQR 42.5-120 days) between repeat LSF calculations. There was a median change in LSF of 0.2% between mapping studies (P = .11). There was no statistical significance between the repeat LSFs regardless of the arterial distribution (P = .79) or between tumor types (P = .75). No patients exceeded lung dose limits using actual or predicted prescribed dose amounts. The actual median lung dose was 2.6 Gy (IQR 1.8-4.4 Gy, maximum = 20.5) for the first radioembolization and 2.0 Gy (IQR 1.3-3.7 Gy, maximum = 10.1) for the second radioembolization.

CONCLUSIONS

No significant difference in LSF was identified between different time points and arterial distributions within the same patient undergoing repeat radioembolization. In patients who receive well under 30-Gy lung dose for the initial treatment and a 50-Gy cumulative lung dose, repeat radioembolization treatments in the same patient may not require a repeat LSF calculation.