Magnetic resonance with manganese-DPDP (mangafodipir) of focal solid pancreatic lesions

Abstract

Purpose: To assess the accuracy of magnetic resonance (MR) with Mangafodipir (Mn-DPDP) in the identification of focal solid pancreatic lesions. The possibility of lesion characterisation based on quantification of Mn uptake was also investigated.

Materials and methods: Thirty-four patients (11 females, 23 males, aged 21-75, mean age 57) selected at sonography (US) and spiral CT (SCT) for clinically suspected focal solid pancreatic lesion, were studied between June 2000 and July 2001. Patients eligible for surgery underwent MR imaging (1.5 T) before and after infusion of 5 micromol/kg of Mn-DPDP (0.5 ml/kg Teslascan, Nycomed Amersham Health, Oslo, Norway). The baseline examination included FSE T2-weighted sequences and fat-saturated and non fat-saturated breath-hold gradient-echo T1-weighted sequences (FMP SPGR). After Teslascan infusion, fat-saturated and non fat-saturated FMP SPGR sequences were repeated. Thirty of the 34 patients had a definitive diagnosis provided by reference standards such as post-operative histology (22 cases), cytology (FNAB) and/or a follow-up period of at least 6 months (8 patients). As regards lesion characterisation, the signal-to-noise ratio (S/N ratio) and contrast-to-noise ratio (C/N ratio) of lesions compared to the pancreatic parenchyma were calculated using ROIs before and after contrast infusion.

Results: The definitive diagnosis was pancreatic malignancy in 18 patients, focal pancreatitis in 5 and neuroendocrine tumours in 3. Four patients with suspected lesions at US and/or SCT were free of focal pancreatic disease. Mn-DPDP MR identified 17/18 malignancies, 2/3 endocrine neoplasms 5/5 focal pancreatitis; the 4 patients with no pancreatic lesions were correctly identified. The Mn-DPDP MR accuracy in detecting focal pancreatic solid lesions was 93%. MR missed 1 small adenocarcinoma (the only pT1 in our group) and 1 insulinoma (with Mn uptake similar to the surrounding parenchyma). Due to the small number of inflammatory lesions included in the study, no significant differences were found in signal intensity and Mn-DPDP uptake between focal pancreatitis and neoplasms.

Conclusions: MR with Mn-DPDP is very accurate in the identification of focal solid pancreatic lesions. Mangafodi-pir is also very useful for excluding the presence of pancreatic lesions suspected at US or CT. The characterisation of lesions, in particular of inflammatory versus neoplastic lesions, remains problematic and requires further investigation.