Radioablation of Upper Abdominal Malignancies by CT-Guided, Interstitial HDR Brachytherapy: A Multivariate Analysis of Catheter Placement Assisted by Ultrasound Imaging

PURPOSE

To evaluate the use of ultrasound (US) during catheter placement in interstitial brachytherapy (iBT) of abdominal malignancies as an alternative to computed tomography (CT) fluoroscopy.

MATERIALS AND METHODS

Catheter placement for CT-guided iBT was, if US visibility was sufficient, assisted by sonography in 52 consecutive patients with 82 lesions (liver N = 62; kidney N = 16; peritoneum N = 4) of various malignancies. We collected data on lesion visibility, location, depth, size, and dosimetry. Comparison of CT fluoroscopy versus US-assisted catheter placement was performed by Fisher's exact test for frequencies and U-test for lesion visibility and dosimetric data. Factors predicting the utility of sonography were determined in a lesion-based multivariate regression analysis. A p-value < 0.05 was regarded as statistically significant.

RESULTS

150 catheters (1 to 6 per lesion; mean diameter 3.6 ± 2.4 cm) were implanted. CT fluoroscopy was used for 44 catheters, and US was used for 106 catheters. Lesion visibility assessed by 5-point Likert scale was significantly better in US (median 2 vs. 3; p = 0.011) and effective dose was significantly reduced if US guidance was applicable (median 1.75 vs. 8.19 mSv; p = 0.014). In a multivariate regression analysis, we identified increased lesion size and caudal location within the target organ to independently predict the utility of ultrasound in catheter placement for iBT.

CONCLUSION

Sonography is a helpful technique to assist CT-guided interstitial brachytherapy of upper abdominal malignancies. Especially for larger lesions localized in the lower liver segments or lower half of the kidney, superior visibility can be expected. As the effective dose of the patient is also reduced, radiation exposure of the medical staff may be indirectly lowered.

KEY POINTS

· Ultrasound-assisted catheter placement in CT-guided brachytherapy of upper abdominal malignancies significantly improves lesion visibility.. · Predictors of successful ultrasound application are larger lesions within the lower portion of the liver and kidney.. · By reducing the need for CT fluoroscopy during intervention, radiation exposure to the medical staff may be indirectly lowered..

CITATION FORMAT

· Damm R, Damm R, Heinze C et al. Radioablation of Upper Abdominal Malignancies by CT-Guided, Interstitial HDR Brachytherapy: A Multivariate Analysis of Catheter Placement Assisted by Ultrasound Imaging. Fortschr Röntgenstr 2022; 194: 62 - 69.

Ultrasound-assisted catheter placement in CT-guided HDR brachytherapy for the local ablation of abdominal malignancies: Initial experience

PURPOSE

 To evaluate the safety and feasibility of sonographically-assisted catheter placement in interstitial high-dose-rate brachytherapy of abdominal malignancies.

MATERIALS AND METHODS

 In an initial cohort of 12 patients and 16 abdominal tumors (colorectal liver metastases n = 9; renal cell cancer n = 3; hepatocellular carcinoma n = 2; cholangiocellular carcinoma n = 2), initial puncture and catheter placement for CT-guided brachytherapy were performed under sonographic assistance when possible. The interventional procedure was prospectively recorded and in-patient data were collected. All data underwent descriptive statistics and comparative analysis by the Mann-Whitney test.

RESULTS

 In 12 out of 16 lesions (diameter 1.5 - 12.9 cm), initial puncture was successfully achieved under ultrasound guidance without utilization of CT fluoroscopy, yielding a significantly shorter mean total fluoroscopy time (14.5 vs. 105.5 s; p = 0.006). In 8 lesions visibility was rated better in ultrasound than in CT fluoroscopy (p = 0.2). No major or minor complications occurred within 30 days after treatment.

CONCLUSION

 Ultrasound-assisted catheter placement during interstitial CT-guided brachytherapy of abdominal tumors could improve catheter positioning and reduce radiation exposure for medical staff.

KEY POINTS

 Ultrasound-assisted catheter placement in CT-guided brachytherapy is safe and feasible. Ultrasound puncture may improve catheter positioning. Reduced CT fluoroscopy time can significantly help to minimize radiation exposure for medical staff.

CITATION FORMAT

· Damm R, El-Sanosy S, Omari J et al. Ultrasound-assisted catheter placement in CT-guided HDR brachytherapy for the local ablation of abdominal malignancies: Initial experience. Fortschr Röntgenstr 2019; 191: 48 - 53.

[Interventional radiological procedures in the therapy for colorectal liver metastases]

Microtherapeutic procedures performed by interventional radiologists pose a viable alternative or additive to systemic chemotherapy for local tumour control in cases of non-operable (for technical, functional, and comorbidity reasons or at the patient's wish) liver metastases. A main focus includes local therapies such as radiofrequency ablation and interstitial brachytherapy which are performed under ultrasound, CT or MRI guidance to achieve a thermal or radiogenic ablation of the malignancy. Although highly effective, these procedures are limited to oligonodular manifestations. For disseminated metastases, locoregional techniques like the yttrium-90 radioembolisation have become established. Here, the active principle in the form of radioactively labelled microspheres is introduced into the liver through an arterial catheter under angiographic guidance. The present article focuses on metastases of colorectal cancer as the most frequent tumour entity encountered in interventional radiotherapy.