Optimal imaging sequence for staging in colorectal liver metastases: analysis of three hypothetical imaging strategies

Background: Computed tomography (CT), positron emission tomography CT (PET-CT) and magnetic resonance imaging (MRI) all play a role in the management of colorectal liver metastases (CRLM), but inappropriate over investigation can lead to delays in treatment and additional cost. This study aimed to determine the optimal sequence for pre-operative imaging pathway to minimise delays to treatment and healthcare costs.

Methods: All patients with colorectal liver metastases referred to a single tertiary liver specialist multidisciplinary team (MDT) between 2008 and 2011 were examined. Primary data of clinical and radiological outcomes of all patients were analysed. These data were used to construct and test 3 hypothetical imaging strategies - 'Upfront', 'Sequential' and 'Hybrid' models.

Results: Six hundred and forty four consecutive patients were included. One hundred and sixty five patients were excluded for curative resection following the initial CT review. Subsequently 167/433 patients did not proceed to hepatectomies. Eighty (47.9%) of these patients had extra-hepatic disease identified on PET-CT, and 29 were due to the exclusion by MRI liver. A resectable pattern of liver disease on initial CT did not exclude patients with occult disease on PET-CT. Based on cost analysis, assessment of initial CT, followed by MDT with subsequent PET-CT and MRI imaging thereafter (Hybrid model), was associated with the shortest time-to-decision and lowest cost.

Conclusions: Resectable pattern of liver metastases should not solely be used to determine the application of PET-CT for staging. Hybrid model is associated with the lowest cost and shortest time-to-treatment.