ABSTRACT
OBJECTIVES: To assess the accuracy of FDG-PET/CT and MR with diffusion-weighted imaging (MR-DWI) for diagnosing peritoneal carcinomatosis (PC) from gastrointestinal malignancies. METHODS: Thirty consecutive patients referred for staging of gastrointestinal malignancy underwent FDG-PET/CT and MR-DWI in this retrospective study. Extent of PC was characterised by dividing the peritoneal cavity into three sites in each patient: right and left supramesocolic areas and inframesocolic level (total 90 sites). Presence of PC was confirmed either by surgery (18/30) or by follow-up (12/30). RESULTS: PC was confirmed in 19 patients (19/30). At a total of 90 sites, 27 showed proven PC. On a patient-based analysis, sensitivity, specificity, PPV, NPV and accuracy were respectively 84%, 73%, 84%, 73% and 80% for PET/CT and 84%, 82%, 89%, 75% and 83% for MR-DWI. On a site-based analysis, overall sensitivity and specificity of PET/CT (63%, 90%) and MR-DWI (74%, 97%) were not statistically different (P = 0.27). In the supramesocolic area, MR-DWI detected more sites involved than PET/CT (7/9 vs. 4/9). The sensitivities of PET and MR were lower for subcentimetre tumour implants (42%, 50%). Interobserver agreement was very good for PET/CT and good for MR-DWI. CONCLUSIONS: FDG-PET/CT and MR-DWI showed similar high accuracy in diagnosing PC. Both techniques underestimated the real extent of PC because of decreased sensitivity for subcentimetre lesions. KEY POINTS: FDG-PET/CT and MR-DWI showed similar high accuracy for diagnosing peritoneal carcinomatosis. ⢠In the supramesocolic area, MR-DWI could be more sensitive than PET/CT. ⢠Both techniques showed lower sensitivity for subcentimetre lesions. ⢠Interobserver agreement was very good for PET/CT and good for MR-DWI.
Subject(s)
Diffusion Magnetic Resonance Imaging/methods , Fluorodeoxyglucose F18 , Gastrointestinal Neoplasms/diagnosis , Magnetic Resonance Imaging/methods , Multimodal Imaging/methods , Peritoneal Neoplasms/diagnosis , Positron-Emission Tomography , Tomography, X-Ray Computed , Adult , Aged , Aged, 80 and over , Early Diagnosis , Female , Humans , Male , Middle Aged , Radiopharmaceuticals , Reproducibility of Results , Sensitivity and Specificity , Subtraction TechniqueABSTRACT
In our hospital as in many others, primary lung cancer is the most frequent indication for FDG PET. Studies have assessed the clinical utility of this imaging modality in characterizing solitary pulmonary nodules or masses, initial staging, defining tumor volume in radiotherapy and searching for recurrence of or restaging non-small cell carcinoma; studies are currently underway to evaluate its use in early assessment of chemotherapy response. Small cell lung cancer has a high FDG uptake and PET/CT can be useful for rapid staging. False negative results may be due to pure bronchioloalveolar carcinomas and endocrine tumors. FDG-PET will certainly play a more important role in the diagnosis and follow-up of pleural cancers in the future. An unexpected positive FDG PET focus should be considered as a warning, but histological proof should precede any irrevocable decisions.