Hiroshi Koike1, Yoshihiro Nishida2, Shinji Ito3, Yoshie Shimoyama4, Kunihiro Ikuta1, Hiroshi Urakawa5, Tomohisa Sakai1, Koki Shimizu6, Kan Ito1, Shiro Imagama1. 1. Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Showa, Nagoya, Japan. 2. Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Showa, Nagoya, Japan; Department of Rehabilitation, Nagoya University Hospital, Showa, Nagoya, Japan. Electronic address: ynishida@med.nagoya-u.ac.jp. 3. Department of Radiology, Nagoya University Hospital, Showa, Nagoya, Japan. 4. Department of Pathology and Laboratory Medicine, Nagoya University Hospital, Showa, Nagoya, Japan. 5. Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Showa, Nagoya, Japan; Department of Clinical Oncology and Chemotherapy, Nagoya University Hospital, Showa, Nagoya, Japan. 6. Department of Orthopedic Surgery, Nagoya Memorial Hospital, Hirabari, Tenpaku, Nagoya, Japan.
Abstract
OBJECTIVE: In patients with neurofibromatosis type 1 (NF1), it is important to accurately determine when plexiform neurofibroma (pNF) transforms to a malignant peripheral nerve sheath tumor (MPNST). The purpose of this study is to investigate the usefulness of diffusion-weighted imaging (DWI) in differentiating pNF and MPNST in NF1 patients. METHODS: Among the NF1 patients who were referred to our hospital between 1985 and 2015, 10 cases of MPNST and 19 cases of pNF were included. We evaluated features of standard magnetic resonance imaging according to the differentiation criteria of malignancy from benignancy as previously reported, apparent diffusion coefficient (ADC) value based on the DWI and the correlation between ADC value and benignancy/malignancy. ROC analysis was performed to determine the appropriate cutoff value of ADC. RESULTS: There were significant differences between MPNST and pNF in the size of the tumor (P = 0.009), peripheral enhancement pattern (P = 0.002), perilesional edema-like zone (P = 0.0008), and intratumoral cystic change (P = 0.02). The mean and minimum values of ADC were significantly lower in MPNST than those in pNF (P = 0.03 and P = 0.003, respectively). When we set a cutoff value of mean ADC as 1.85 × 10-3 mm2/s, the sensitivity and specificity were 80% and 74%, respectively. The area under the curve value improved by adding the Wasa score to the mean ADC evaluation. CONCLUSIONS: ADC values determined by DWI are useful in differentiating MPNST from pNF and adding ADC evaluation to standard MRI evaluation improved the diagnostic accuracy.
OBJECTIVE: In patients with neurofibromatosis type 1 (NF1), it is important to accurately determine when plexiform neurofibroma (pNF) transforms to a malignant peripheral nerve sheath tumor (MPNST). The purpose of this study is to investigate the usefulness of diffusion-weighted imaging (DWI) in differentiating pNF and MPNST in NF1 patients. METHODS: Among the NF1 patients who were referred to our hospital between 1985 and 2015, 10 cases of MPNST and 19 cases of pNF were included. We evaluated features of standard magnetic resonance imaging according to the differentiation criteria of malignancy from benignancy as previously reported, apparent diffusion coefficient (ADC) value based on the DWI and the correlation between ADC value and benignancy/malignancy. ROC analysis was performed to determine the appropriate cutoff value of ADC. RESULTS: There were significant differences between MPNST and pNF in the size of the tumor (P = 0.009), peripheral enhancement pattern (P = 0.002), perilesional edema-like zone (P = 0.0008), and intratumoral cystic change (P = 0.02). The mean and minimum values of ADC were significantly lower in MPNST than those in pNF (P = 0.03 and P = 0.003, respectively). When we set a cutoff value of mean ADC as 1.85 × 10-3 mm2/s, the sensitivity and specificity were 80% and 74%, respectively. The area under the curve value improved by adding the Wasa score to the mean ADC evaluation. CONCLUSIONS: ADC values determined by DWI are useful in differentiating MPNST from pNF and adding ADC evaluation to standard MRI evaluation improved the diagnostic accuracy.