MR features of peripheral nerve sheath tumors: can a calculated index compete with radiologist's experience?

Abstract

The aims of this study were, firstly, to provide a formula (neurogenic index) based on MR characteristics used in daily routine for predicting whether a soft tissue tumor is neurogenic or not, secondly, to test prospectively the performance of this formula, and thirdly, to compare this performance with that of radiologists experienced in MR imaging of soft tissue tumors. Retrospectively, MR images of 70 neurogenic and 70 non-neurogenic soft tissue tumors were evaluated in random order by two teams of two observers each. A neurogenic index (NI) was calculated based on those MR parameters that showed no or minor interobserver variability. Subsequently, three investigators in concert used the NI in a validation group of 15 neurogenic and 22 nonneurogenic soft tissue tumors. The same team, based on their own experience, tried to differentiate in the same validation group neurogenic from non-neurogenic soft tissue tumors. This was expressed in a subjective score (SS). Sensitivity, specificity, and predictive values were calculated. NI comprised spread (intra- or extracompartmental), distribution, fluid-fluid levels, homogeneity on T2-weighted images (WI), highest signal intensity (SI) on T1WI, lowest SI on T2WI, and delineation on T2WI. In the validation group, NI had a sensitivity of 88.6%, a specificity of 52.0%, a positive predictive value (PPV) of 54.1%, and a negative predictive value (NPV) of 84.6% for neurogenic tumors. The subjective score SS was superior and had a sensitivity of 93.3%, a specificity of 77.2%, a PPV of 73.7%, and a NPV of 94.4%. Our NI was less accurate than the SS; however, the low number of false-negative diagnoses for neurogenic tumors warrants continued efforts in development of neural networks.

Multiple Ipsilateral Lower Extremity Masses in a 46-year-old Man

“…On MRI, they generally show low signal intensity on T1-weighted images and heterogeneous high signal on T2 sequences. 24 Often, they show the split-fat sign, which refers to the fat splayed along either side of the lesion as a result of its localization to interfascial planes. The string sign, which describes the appearance of a nerve leading up to and away from a mass, is strongly suggestive of a neurogenic tumor.…”

“…The string sign, which describes the appearance of a nerve leading up to and away from a mass, is strongly suggestive of a neurogenic tumor. 20,24 Calcifications are highly nonspecific and can be seen in tumors benign and malignant. Benign soft tissue tumors that most typically contain calcifications include hemangiomas, pigmented villonodular synovitis, calcific myonecrosis, soft tissue chondromas, and occasionally lipomas.…”

Ultrasonographic and Clinical Characteristics of Schwannoma of the Hand

“… 4 5) Although magnetic resonance imaging (MRI) has proven to be the most effective imaging modality, ultrasonography has become more widely used due to its relatively lower cost. 6) With the development of higher resolution techniques, the use of ultrasonography in diagnose of hand diseases has increased, and now it is the primary diagnostic tool for a mass lesion of the hand. Schwannoma has variable sonographic features.…”

Soft Tissue Tumors about the Shoulder

“…34 In NF 1, there are usually multiple neurogenic tumors, and malignant degeneration should be suspected in large inhomogeneous lesions. Imaging parameters that help to distinguish benign from malignant peripheral nerve sheath tumors are summarized 35 in ►Table 6.…”