^99mTc-MAA Scintigraphy for Assessing Hepatic Arterial Infusion Pump: The Rate Being a Snare

Abstract

For liver-directed parenteral therapies in cholangiocarcinoma and colorectal liver metastases, the hepatic arterial infusion pumps (HAIPs) are used to maximize the drug concentrations within the malignant tumors. The patency and normal functioning of the HAIP system is assessed by radionuclide imaging with ^99mTc-MAA. We bring forth a relatively rare instance where the rate of infusion of the radiopharmaceutical determines the appearance of the hepatogram in the scan.

 

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Keywords

^99mTc-MAA - hepatic arterial infusion pump - liver-directed therapy

Introduction

The hepatic arterial infusion pump (HAIP) catheters are surgically inserted in a retrograde direction into the gastroduodenal artery (GDA) with the tip at the junction of the GDA and common hepatic artery, allowing arterially delivered chemotherapy via the pump. In unresectable situations, HAIP is used to deliver chemotherapy agents to cholangiocarcinoma and colorectal liver metastases. Since the neovascularity of hepatic malignant tumors is derived predominantly from branches of the hepatic artery, this type of drug delivery exploits the hepatic first pass metabolism and maximize the drug concentrations in the tumors alongside decreasing systemic levels of the drug and thereby toxicity.[1] [2] This approach was previously shown to increase the survival rates of patients.[3] [4]

Proper functioning of the HAIP system, i.e., the exclusivity of liver distribution and absence of extra-hepatic perfusion, is ensured by planar and SPECT/CT (single-photon emission computed tomography/computed tomography) radionuclide imaging with ^99mTc-MAA.[5] We bring forth a relatively rare instance when the rate of infusion of the radiopharmaceutical determines the appearance of the scan.

 

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Case Report

A 35-year-old gentleman with sigmoid colon cancer s/p subtotal colectomy followed by adjuvant systemic therapy had metastases to liver subsequently. The patient was next evaluated for a hepatic pump placement for a liver-directed therapy. Pre-therapy abdominal CT angiography showed that there is trifurcation of right common hepatic artery, a normal vascular variant ([Fig. 1]).

Fig. 1 Abdominal CT angiography showing trifurcation of right common hepatic artery into right hepatic artery, left hepatic artery, and gastro-duodenal artery (yellow arrow). CT, computed tomography.

HAIP was surgically placed over the left anterior abdominal wall with the tip of the catheter in GDA. Hepatic bilobar methylene blue was seen intraoperatively, confirming successful pump placement. 5.0 mCi ^99mTc-MAA was infused into the pump as a bolus, per usual protocol, to assess the patency of the pump and evaluate for extra-hepatic abnormal perfusion. As detailed in [Fig. 2], there was heterogenous activity in the right hepatic lobe with minimal activity within the left hepatic lobe. No extra-hepatic activity noted.

Fig. 2 Planar and SPECT/CT images with 5.0 mCi ^99mTc-MAA showing heterogenous activity in the right hepatic lobe with minimal activity within left hepatic lobe (blue arrow) and no extra-hepatic activity. CT, computed tomography; SPECT, single-photon emission computed tomography.

Repeat study was done 4 days later with 4.3 mCi of ^99mTc-MAA infused at half the usual bolus rate, to simulate real-world chemotherapy infusion through the port. As detailed in [Fig. 3], the repeat study showed heterogenous bilobar activity and no evidence of extra-hepatic activity.

Fig. 3 Planar and SPECT/CT images with 4.3 mCi of ^99mTc-MAA showing activity in both the hepatic lobes (blue arrow). CT, computed tomography; SPECT, single-photon emission computed tomography.

 

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Discussion

The HAIP system remains a viable option to control unresectable hepatic metastatic disease burden and as an adjuvant therapy to decrease recurrence after resected metastases. When handled as part of a multi-disciplinary team, they are considered safe and efficacious, with improved patient survival.[6]

HAIPs are manufactured in such a way that the chemotherapy agents are delivered to the liver from the pump reservoir over a few weeks. The expected findings of a nuclear medicine liver perfusion scan were previously published.[7] The patient described in the above case report had trifurcation of common hepatic artery, with right and left hepatic arteries branching from it rather than proper hepatic artery. It is unclear if this unique appearance on the emission images is a result of the vascular variance.

This case study highlights the importance of slow infusion of the radiopharmaceutical during the hepatic pump study, particularly in patients with normal vascular variants. Appropriate recognition of this pitfall may avoid further unnecessary corrective procedures.

 

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Conflict of Interest

None declared.

• References

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• 2 IJzerman NS, Filipe WF, Bruijn P. et al. Systemic exposure of floxuridine after hepatic arterial infusion pump chemotherapy with floxuridine in patients with resected colorectal liver metastases. Biomed Pharmacother 2023; 162: 114625
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• 4 Kemeny NE, Niedzwiecki D, Hollis DR. et al. Hepatic arterial infusion versus systemic therapy for hepatic metastases from colorectal cancer: a randomized trial of efficacy, quality of life, and molecular markers (CALGB 9481). J Clin Oncol 2006; 24 (09) 1395-1403
• 5 Raphael B, Akhurst T, Rao V, Getrajdman G, Kemeny N. Hepatic arterial pump perfusion. The value of macroaggregated albumin (MAA) SPECT/CT in comparison with MAA planar and SPECT imaging. Journal of Nuclear Medicine 2007; 48: 390
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• 7 Napier KJ, Lidsky ME, James OG, Wildman-Tobriner B. Hepatic arterial infusion pumps: What the radiologist needs to know. Radiographics 2021; 41 (03) 895-908

Publication History

Article published online:
05 July 2025