Whole body MR imaging in neurofibromatosis type 1

To assess the value of whole body MR imaging in patients with neurofibromatosis type 1 (NF1).

24 patients (15-59 years; mean and median 36 years; 7 males; 17 females) with genetically proven neurofibromatosis type 1 were examined with whole body MR imaging. Axial and coronal T1- and fat-suppressed T2-weighted images (slice thickness 6-12 mm) were acquired on a 1.5T MR unit (Symphony; Siemens, Erlangen, Germany). The images were reviewed by 2 radiologists: 1 senior, 1 junior. The criterion for a neurofibroma was a mass lesion with low signal intensity on T1 and high signal intensity on T2, along the course of a nerve. The location, size, general morphology and course along plexuses and nerves were evaluated. Cutaneous and subcutaneous neurofibromas were defined as "superficial" neurofibromas. The other neurofibromas were regarded as "deep" neurofibromas.

There were no major problems to differentiate neurofibromas from lymph nodes, vessels or cysts. The latter three were easily recognised by their typical shape and location, whereas neurofibromas occurred in regions where no mass lesion was anatomically expected. There was no relation between age and total number of neurofibromas throughout the body. Classification according to location and number of neurofibromas: 8 patients had only superficial neurofibromas, 1 only deep and 15 both superficial and deep lesions. Twelve patients had less than 15 neurofibromas and 12 had more. Classification according to course: in 8 patients the neurofibromas occurred along plexuses or proximal part of the intercostal nerves; in 16 patients the lesions were more peripheral. Classification according to morphology: 4 patients had plexiform neurofibromas and 20 patients had multiple solitary lesions. Twelve of these 20 patients had less than 15 lesions, and 8 had more. In 2 patients multiple solitary neurofibromas occurred along the nerve in a chain configuration. In one patient a clinically unsuspected brain tumour was found.

Whole body MR imaging is a reliable method to evaluate the distribution, size and morphology of neurofibromas in patients with NF1.