Reproducibility of Parenchymal Blood Volume Measurements Using an Angiographic C-arm CT System

Baseline parenchymal blood volume is a potential prognostic imaging biomarker in patients with malignant liver tumors treated with transarterial chemoembolization

PURPOSE

To assess the prognostic value of Parenchymal Blood Volume (PBV) in predicting survival, tumor response, and PBV response after transarterial chemoembolization (TACE).

METHODS

A total of 137 patients with malignant liver tumors who were treated with TACE between 07/2016 and 07/2018 were evaluated. Computed tomography illustrations were reworked at a dedicated workstation to create a PBV map which was overlapped with the associated magnetic resonance image to determine tumor diameter and PBV. Patients were divided into two groups according to their initial PBV value: PBV < 50 or ≥ 50 ml/l.

RESULTS

Retrospectively, for patients with at least 2 TACE and initial PBV < 50 ml/l (n = 27), the tumor volume, regardless of the primary tumor type, decreased by 13.26%, and PBV showed a decrease of 23.11%. For 84 patients with PBV ≥ 50 ml/l, the tumor volume decreased by 24.01%, and PBV showed a more substantial decrease of 44.69% (both p < 0.001). In the overall study population (n = 137), patients with an initial PBV ≥ 50 ml/l (n = 101) survived for an average of 15.05 months, while patients with an initial PBV < 50 ml/l (n = 36) survived for 10.01 months (p < 0.002). Subgroup analysis indicated that median survival in the HCC group was longer at PBV ≥ 50 ml/l. For CRC and other primary tumors, the survival time for high and low initial PBV was almost identical.

CONCLUSION

Our study reveals a noteworthy correlation between high initial PBV values and a significant reduction in both relative and absolute tumor volume. This association suggests a potential prognostic indicator, indicating that elevated PBV may signify a more favorable response to transarterial chemoembolization (TACE). Additionally, patients with high initial PBV values experienced an extended overall survival time. Notably, the subgroup analysis highlighted a prolonged survival time in the HCC group with elevated initial PBV values. These findings underscore the potential significance of assessing PBV as a predictive factor in the context of TACE, especially in specific tumor entities such as HCC. Further investigations are essential to validate and extrapolate these observations to optimize patient outcomes.

Renal perfusion improvement in the perioperative period after unilateral endovascular revascularization in patients with atherosclerotic renal artery stenosis

Background

The clinical benefits of endovascular treatment in renal artery stenosis (RAS) remain controversial. This study used an intraoperative renal perfusion imaging technique, called flat-panel detector parenchymal blood volume imaging (FD-PBV), to observe the change in renal perfusion after endovascular treatment in RAS.

Materials and methods

In a prospective, single-center study, we assigned 30 patients with atherosclerotic RAS who underwent endovascular treatment between March 2016 and March 2021. The preoperative and postoperative results of renal perfusion, blood pressure, and renal function, were compared.

Results

Both median kidney volume (p < 0.001) and median preoperative mean density of contrast medium (MDCM) (p = 0.028) increased significantly after endovascular treatment. The ratio of postoperative and preoperative MDCM differed greatly among the patients. For patients with preoperative MDCM <304.0 HU (Subgroup A, 15 cases), MDCM significantly increased after treatment (p = 0.001) and 12 (80.0%) patients had more than 10% increase in renal perfusion. For patients who had relatively high preoperative renal perfusion (MDCM ≥304.0 HU, Subgroup B, 15 cases), preoperative and postoperative MDCM were similar (p = 0.776). On the other hand, the serum creatinine levels significantly decreased in Subgroup A (p = 0.033) and fewer antihypertensive drugs were used after endovascular revascularization (p = 0.041). The preoperative and postoperative creatinine levels and number of antihypertensive drugs were similar in Subgroup B.

Conclusions

During the perioperative period, RAS patients with relatively low preoperative renal perfusion levels had greater improvement in renal perfusion, renal function, and blood pressure control after endovascular treatment. The improvement of renal function needs to be confirmed by long-term follow-up.

Can cone-beam CT tumor blood volume predicts the response to chemoembolization of colorectal liver metastases? Results of an observational study

PURPOSE

To determine whether intraprocedural C-arm cone-beam CT (CBCT) parenchymal blood volume (PBV) can predict the response of colorectal cancer liver metastases (CRCLM) 2 months after irinotecan drug-eluting bead (DEBIRI) chemoembolization.

MATERIALS AND METHODS

This single-center observational study was compliant with the Helsinki Declaration and approved by our institutional review board. Thirty-four consecutive CRCLM patients referred for DEBIRI chemoembolization were enrolled between March 2015 and December 2016. Tumor size was assessed at baseline and 2 months after DEBIRI chemoembolization by multidetector CT (Response Evaluation Criteria in Solid Tumors RECIST 1.0), and PBV was measured before and after DEBIRI chemoembolization. Two independent readers reviewed all data. We determined the potential correlation (Spearman's rank correlation) between intraprocedural PBV values and tumor response at 2 months. The relationship between tumor response and PBV was studied using a mixed model. A logistic regression model was applied to study the relationship between patient "Responder/Non-responder" and PBV.

RESULTS

There was a strong correlation between baseline PBV or the percent change of PBV and the 2-month tumor response (rho = - 0.8587 (p = 0.00001) and rho = 0.8027 (p = 0.00001), respectively). The mixed model showed that an increase of 1 ml/1000 ml in PBV of a tumor before DEBIRI chemoembolization led to a 0.54 mm decrease in diameter (p < 0.005). A 1% decrease in PBV after DEBIRI chemoembolization resulted in tumor shrinkage of 0.75 mm (p < 0.005). The logistic regression model showed that patients with a 1% smaller mean decrease of PBV after DEBIRI chemoembolization had a 10% lower likelihood of achieving disease control (OR = 0.9, 95% confidence interval (CI) = 0.81-1; p = 0.0493).

CONCLUSION

Intraprocedural PBV may predict tumor response to DEBIRI chemoembolization.

KEY POINTS

• There is a strong relationship between the parenchymal blood volume (PBV) of colorectal liver metastases before DEBIRI chemoembolization and tumor response at 2 months. • Higher PBV values before DEBIRI chemoembolization correlate with greater tumor shrinkage, but only if the PBV decreases by more than 70% after DEBIRI chemoembolization. • Each increase of 1% in the mean decrease of PBV after DEBIRI chemoembolization resulted in a 10% lower likelihood of achieving disease control (OR = 0.9, 95% confidence interval (CI) = 0.81-1; p = 0.0493).

Dynamic Measurement of Arterial Liver Perfusion With an Interventional C-Arm System

PURPOSE

Objective intraprocedural measurement of hepatic blood flow could provide a quantitative treatment end point for locoregional liver procedures. This study aims to validate the accuracy and reproducibility of cone-beam computed tomography perfusion (CBCTp) measurements of arterial liver perfusion (ALP) against clinically available computed tomography perfusion (CTp) measurements in a swine embolization model.

METHODS

Triplicate CBCTp measurements using a selective arterial contrast injection were performed before and after complete embolization of the left lobe of the liver in 5 swine. Two CBCTp protocols were evaluated that differed in sweep duration (3.3 vs 4.5 seconds) and the number of acquired projection images (166 vs 248). The mean ALP was measured within identical volumes of interest selected in the embolized and nonembolized regions of the perfusion map generated from each scan. Postembolization CBCTp values were also compared with CTp measurements.

RESULTS

The 2 CBCTp protocols demonstrated high concordance correlation (0.90, P < 0.001). Both CBCTp protocols showed higher reproducibility than CTp in the nontarget lobe, with an intraclass correlation of 0.90 or greater for CBCTp and 0.83 for CTp (P < 0.001 for all correlations). The ALP in the embolized lobe was nearly zero and hence excluded for reproducibility. High concordance correlation was observed between the CTp and each CBCTp protocol, with the shorter CBCTp protocol reaching a concordance correlation of 0.75 and the longer achieving 0.87 (P < 0.001 for both correlations).

CONCLUSIONS

Dynamic blood flow measurement using an angiographic C-arm system is feasible and produces quantitative results comparable to CTp.