Article Figures & Data
Figures
- Fig 1.
Boxplot shows median (thick horizontal lines within boxes), interquartile range (heights of boxes), and smallest and largest (lines protruding from boxes) ADC values within Group 1 (benign masses), Group 2 (malignant lesions), and Group 3 (postradiation changes). Group 1 (n = 10) included schwannomas and neurofibromas; Group 2 (n = 7) included 1 rhabdomyosarcoma, 1 malignant peripheral nerve sheath tumor, 2 cases of metastatic breast cancer, 1 case of metastatic renal cell carcinoma, 1 diffuse large B-cell lymphoma, and 1 case of acute lymphoblastic leukemia. Group 3 (n = 6) consisted of postradiation changes with no evidence for residual tumor. Group 3 (postradiation changes) demonstrated the highest median ADC value of 2.50 × 10−3 mm2/s (interquartile range = 0.87 × 10−3 mm2/s, minimum = 1.39 × 10−3 mm2/s, maximum = 3.22 × 10−3 mm2/s), followed closely by benign lesions (Group 1) with a median ADC value of 1.81 × 10−3 mm2/s (interquartile range = 0.98 × 10−3 mm2/s, minimum = 1.30 × 10−3 mm2/s, maximum = 2.97 × 10−3 mm2/s). Malignant lesions (Group 2) recorded the lowest median ADC value of 0.69 × 10−3 mm2/s (interquartile range = 0.49 × 10−3 mm2/s, minimum = 0.26 × 10−3 mm2/s, maximum = 1.08 × 10−3 mm2/s).
- Fig 2.
Biopsy-proven schwannoma of the left median nerve in a 48-year-old woman presenting with left upper extremity pain and paresthesias. Axial fat-suppressed T2 (A), axial fat-saturated postgadolinium T1 (B), maximum-intensity-projection DWI (C), and axial ADC (D) demonstrate a vividly enhancing, heterogeneously T2 hyperintense mass (arrows) along the median nerve. The ADC value within the mass was 2.1 ± 0.36 × 10−3 mm2/s. The lesion was resected due to progressive symptoms.
- Fig 3.
Biopsy-proven neurofibroma of the left S1 and sciatic nerves in a 6-year-old boy with left foot drop. Coronal T1 (A), coronal fat-saturated postgadolinium T1 (B), oblique reformatted coronal STIR (C), and coronal ADC (D) demonstrate enhancing masslike T2 hyperintense soft tissue (arrows) along the left S1 nerve and left sciatic nerve. The lesion was treated with radiation therapy.
- Fig 4.
Metastatic renal cell carcinoma in a 46-year-old woman with left arm weakness. Axial STIR (A), axial fat-saturated postgadolinium T1 (B), axial DWI (C), and axial ADC (D) demonstrate a T2 hyperintense, enhancing mass (arrows) along the left C6 nerve just outside the left C5–C6 neural foramen. ADC within the mass was 1.08 ± 0.09 × 10−3 mm2/s. The mass was subtotally resected and irradiated.
- Fig 5.
Malignant peripheral nerve sheath tumor in a 69-year-old man with several years of right lower extremity pain and anterior thigh numbness. Percutaneous biopsy several years earlier had demonstrated benign schwannoma. Gross total resection was performed for presumed schwannoma, with areas of necrosis attributed to the large size of the mass and outgrowth of blood supply. Final pathologic diagnosis was malignant peripheral nerve sheath tumor. Axial T1 (A), axial fat-saturated postgadolinium T1 (B), coronal STIR (C), and axial ADC (D) demonstrate a large mass (thick arrows) extending from a widened right L2–L3 neural foramen along the expected course of the right femoral nerve at the posterior aspect of the right psoas muscle. The right psoas muscle (dashed arrow) is draped and elongated over the anterior aspect of the mass. Th right kidney (small dotted arrow) is displaced superiorly. D, ADC ROIs (circle) were selected to avoid nonenhancing areas (thin solid arrows in B–D) thought to represent necrosis. The mean ADC within nonnecrotic regions in the mass was 0.26 × 10−3 mm2/s.
- Fig 6.
Biopsy-proven non-Hodgkin lymphoma infiltrating the right sciatic nerve. Axial STIR (A), axial fat-saturated postgadolinium T1 (B), and axial ADC map (C) demonstrate a T2 hyperintense minimally enhancing soft-tissue mass (arrows) along the right sciatic nerve at the greater sciatic foramen. ADC within the mass was 0.69 ± 0.33 × 10−3 mm2/s. CT-guided biopsy was nondiagnostic. D, MR imaging–guided biopsy was performed, yielding a pathologic diagnosis of diffuse large B-cell lymphoma. The patient underwent chemotherapy and radiation to the mass.
- Fig 7.
Biopsy-proven metastatic breast cancer infiltrating the right brachial plexus in a 53-year-old woman with right upper extremity pain. Axial T1 (A) and axial STIR (B) images demonstrate a thickened, T2 hyperintense right first thoracic nerve (arrows) with effacement of the fascicular structure normally visible on T1-weighted images. Coronal STIR (C) and maximum-intensity-projection DWI (D) demonstrate asymmetrically increased DWI signal in the right T1 nerve and inferior trunk of the right brachial plexus (arrows), with a corresponding mean ADC of 0.95 ± 0.05 × 10−3 mm2/s. The patient underwent palliative radiation therapy.
- Fig 8.
Postradiation brachial plexopathy in a 42-year-old woman with progressive right upper extremity weakness, beginning in the hand and progressing proximally. She had undergone resection and radiation therapy 12 years earlier for high-grade round cell sarcoma of the right brachial plexus. Axial STIR (A), maximum-intensity-projection coronal oblique STIR (B), sagittal T1 (C), sagittal STIR (D), coronal STIR (E), and coronal ADC (F) demonstrate a soft-tissue mass (arrows) and a thickened, T2 hyperintense right brachial plexus (asterisks) with an average ADC of 2.59 ± 0.16 × 10−3 mm2/s. Although symptoms persisted, the appearance of the mass and the enhancing, T2 hyperintense brachial plexus were unchanged over multiple follow-up MR imaging examinations over 60 months, and a final diagnosis of postradiation brachial plexopathy was made. The soft-tissue mass likely represents fibrosis related to surgical resection of the mass and subsequent radiation.
- Fig 9.
Marked increase in diffusivity following radiation therapy for metastatic breast cancer in a 47-year-old woman with pain in the left L4 through S2 distribution. Axial fat-saturated postgadolinium T1 and ADC before (A and B) and 4 months following completion of radiation therapy (C and D). Initial images (A and B) demonstrate metastatic disease throughout the sacrum and infiltrating the left S1 nerve (arrows). B, Before radiation, ADC within the diseased left S1 nerve was 0.78 ± 0.15 × 10−3 mm2/s. D, Four months later, following completion of radiation therapy, ADC within the nerve had markedly increased to 1.39 ± 0.23 × 10−3 mm2/s.
