Tumor detection by diffusion-weighted MRI and ADC-Mapping - Initial clinical experiences in comparison to PET-CT

Objective: To evaluate the clinical potential of diffusion-weighted-imaging (DWI) with apparent diffusion coefficient (ADC)-mapping for tumor detection. Materials and Methods: A single-shot echo-planar-imaging DWI sequence with fat suppression and ability for navigator-based respiratory triggering was implemented. Nineteen patients (I I melanoma, 4 prostate cancer, 1 non-Hodgkin lymphoma, and 3 lung cancer) were examined by positron emission tomography (PET) with an integrated computed tomography scanner (PETCT) and DWI. Images at b = 0, 400, and 1000 S/mm(2) were acquired and ADC maps were generated. PET examinations were used as a reference for tumor detection. Four hundred twenty-four regions of interest were used for DWI and 73 for PET data evaluation. Results: DWI and ADC maps were of diagnostic quality. Metastases with increased tracer uptake were clearly visualized at b = 1000 s/mm(2) with the exception of mediastinal lymph node metastases in cases of lung cancer. ADC mapping did not improve detection rates. Conclusions: DWI is a feasible clinical technique, improving the assessment of metastatic spread in routine magnetic resonance imaging examinations.