Comparison of the hepatic perfusion index measured with gadolinium-enhanced volumetric MRI in controls and in patients with colorectal cancer

Autor: John J. Totman, R L O'Gorman, J B Karani, P A Kane
Rok vydání: 2005
Předmět:
Zdroj: The British Journal of Radiology. 78:105-109
ISSN: 1748-880X
0007-1285
DOI: 10.1259/bjr/13525061
Popis: The aim of the study was to adapt the methodology established for dynamic CT measurements of the hepatic perfusion index (HPI) to MRI, and to assess the potential role of MRI measurements of the HPI in detecting regional alterations in liver perfusion between patients with colorectal liver metastases and normal controls. The HPI was evaluated from serial T1 volume acquisitions acquired over the course of a Gd-DTPA bolus injection. Time-course data from regions of interest in the liver, spleen and aorta were used to calculate the HPI; and HPI data from control subjects were compared with data from patients with known colorectal metastases. Significant differences were found between the relative portal perfusion and hepatic perfusion indices calculated for the patient and control groups (p,0.005). These results suggest that hepatic perfusion indices can be derived using MRI-based methods, and that these perfusion indices are sensitive to differences in liver perfusion associated with established metastatic liver disease on imaging. This technique may contribute to the early detection of liver metastases, allowing early surgical intervention and improved patient survival. Colorectal cancer is the second most common cause of death from cancer in the UK. Currently 33 000 new cases are diagnosed each year and the incidence is increasing yearly by 1% in men (1). For patients with colorectal malignancy, the presence of liver metastases is the most accurate predictor of survival. Following apparently curative surgical resection of the primary tumour, 50% of patients will die within 5 years, the majority from disseminated disease. Hepatic involvement is a feature in 50% of patients, and in almost one-third of cases the liver may be the only site of metastatic disease found at autopsy (2). Improved survival following liver resection is now achievable with 5-year disease-free survival rates of 20- 45% and up to 60% in unifocal disease (3). Without surgery, the 5-year survival rate for these patients is effectively zero (4). Detection of focal liver lesions pre-operatively is dependent on fundamental differences in the tissue characteristics of tumour and normal liver: first, an intrinsic difference in tissue density and cellular compo- nents; second, differences in vascularity and tissue haemodynamics. Current imaging techniques can reliably demonstrate metastases of 1 cm or larger using super- paramagnetic iron oxide (SPIO)-enhanced MRI and multidetector CT. The sensitivity of imaging methods for detection of lesions smaller than 1 cm is in the region of 50% when surgery and intraoperative ultrasound are used as the gold standard, but the accuracy of this reference standard itself cannot be established (5). Even if detected, the characterization of lesions of 1 cm or less may be suboptimal on pre-operative imaging. It is these undetected, subcentimetre lesions that typically account for early disease recurrence within the liver and failure of surgical cure (5). It is now established practice in centres carrying out liver resection to use a focused, multimodality approach, using CT, MRI and PET in order to enhance detection of lesions, and intrahepatic and extrahepatic staging.
Databáze: OpenAIRE
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