PREDICTION OF SURGICAL RESECTABILITY IN PATIENTS WITH HEPATIC COLORECTAL METASTASES

Objective To evaluate the efficacy of two distinct imaging techniques to predict, before operation, unresectability compared with standard c omputed tomographic scan (CT). Summary Background Accurate preoperativ e identification of the number, size, and location of hepatic lesions is crucial in planning hepatic resection for colorectal hepatic metast ases. Although infusion-enhanced CT is the standard, its limitations a re the imaging of relatively isodense and/or small (<1 cm) lesions. Th e increased sensitivity of CT arterial portography (CTAP) may be offse t by false-positive results caused by benign lesions and flow artifact s. Methods Fifty-eight selected patients considered to be eligible for resection by standard CT had laparotomy. Before operation and in addi tion to CT, all patients had CT arterial portography and hepatic arter y perfusion scintigraphy (HAPS) using radiolabeled macroaggregated alb umin. Early studies showed an increased sensitivity for detecting smal l lesions using the invasive CTAP. Similarly, the HAPS study has detec ted malignant lesions not observed by standard CT. Results Of 58 patie nts having laparotomy, 40 were resectable by either lobectomy (22) or trisegmentectomy (1) and the rest by single or multiple wedge resectio ns. Eighteen patients could not be resected because of combined intra- and extrahepatic disease or the number and location of metastases. St andard CT detected 64% of all lesions (12% of lesions less than 1 cm). Unresectability was accurately predicted by CTAP and HAPS in 16 (88%) and 15 (83%), respectively, of the 18 patients considered ineligible for resection at laparotomy. Of the 40 patients who had resection for possible cure, CTAP and HAPS falsely predicted unresectability in 6 of 40 patients (15%) and in 10 of 40 patients (25%), respectively. The p ositive predictive value for unresectability of CTAP and HAPS was 73% and 60%, respectively. False-positive lesions after CTAP included hema ngiomas, cysts, granulomas, and flow artifacts. False-positive HAPS le sions included patients in whom no tumor was found at surgery but with some identified by intraoperative ultrasound, blind biopsy, and blind resection. Conclusions False-positive results by HAPS and CTAP may li mit the ability of these tests to accurately predict unresectability b efore operation and may deny patients the chance for surgical resectio n. The HAPS study does, however, detect small lesions not seen by CT o r CTAP. Standard CT, although less sensitive, followed by surgery and intraoperative ultrasound, does not necessarily preclude patients who could be resected.