New method for the assessment of perineural invasion from perihilar cholangiocarcinoma.

PURPOSE: Perineural invasion (PN) is often found in perihilar cholangiocarcinoma. New procedure was developed to assess PN around the right hepatic artery (RHA) using dual-energy computed tomography (DECT). METHODS: Thirty patients with perihilar cholangiocarcinoma who underwent DECT before biliary drainage were retrospectively reviewed. Mask images, i.e., the periarterial layer (PAL) around the RHA and superior mesenteric artery (SMA), were made from late arterial phase DECT. The mean CT number of the PAL was measured. RESULTS: Twenty patients with PN around the RHA were classified into the PN (+) group. The remaining 10 patients without PN and other 26 patients with other diseases that are never accompanied with PN were classified into the PN (-) group. The PAL ratio (the CT number of the PAL around the RHA relative to that around the SMA) was calculated. Both the mean CT number of the PAL around the RHA and the PAL ratio were significantly higher in the PN (+) group than in the PN (-) group. According to an ROC analysis, the predictive ability of the PAL ratio was superior. Using the cutoff value of the PAL ratio 1.009, a diagnosis of PN around the RHA was made with approximately 75% accuracy. CONCLUSIONS: Assessment with CT number of the PAL reconstructed from DECT images is an easy and objective method to diagnose PN.

A radiological classification system for intraneural vascular anomalies: assessment of potential for resection with high-resolution MRI.

BACKGROUND: Intraneural hemangiomas and vascular malformations are rare, with approximately 50 cases reported in the literature. They present a therapeutic challenge; surgical resection can result in damage to the nerve and lesion recurrence is common. We introduce a new framework to classify intraneural vascular anomalies in relation to the anatomic compartments of the nerve and assess amenability to surgical resection. METHODS: We retrospectively reviewed cases of intraneural hemangiomas and vascular malformations treated at our institution between 2003 and 2013 that had high-resolution 3-T magnetic resonance imaging (MRI). A review of the literature was also performed. Our cases and reports in the literature with available MRI data were sub-categorized according to their relationship to the paraneurium and epineurium of the nerve. RESULTS: Nine patients were identified with intraneural (subparaneurial or subepineurial) vascular lesions. Two patients had a predominantly subparaneurial involvement of the nerve, six patients had predominantly subepineurial involvement, and one patient exhibited extensive involvement in both compartments. Four patients were managed surgically and the rest conservatively. Targeted resection of two subparaneurial hemangiomas provided complete relief of symptoms and freedom from recurrence at 18 month and 24 months respectively. One patient with extensive subepineurial and extraneural vascular malformations did not appear to benefit from sub-total resection with interfascicular dissection. No surgical morbidity was noted in any of the cases. CONCLUSIONS: We believe that the subparaneurial compartment-a potential space between the epineurium and paraneurium-provides a tissue plane within which benign vascular lesions can occur. Hemangiomas and vascular malformations are complex and can occupy different intraneural and extraneural compartments. The anatomic framework aids surgical decision-making and ensures that all components of the lesion are considered. We advocate a multimodal approach in the treatment of these rare lesions.

High-Resolution Ultrasound for Diagnostic Assessment of the Great Auricular Nerve--Normal and First Pathologic Findings.

PURPOSE: The great auricular nerve (GAN) is a sensory branch of the superficial cervical plexus. While its blockade is an established procedure, little is known about the ultrasound appearance of pathologic conditions of the GAN itself. We, therefore, aimed to evaluate the possibility of the visualization and diagnostic assessment of the GAN along its entire course by means of high-resolution ultrasound (HRUS). MATERIALS AND METHODS: To assess the feasibility of visualization, we performed HRUS with an 18 MHz probe, HRUS-guided, fine-needle ink markings and consecutive dissection in six anatomical specimens. Then, we measured the diameter of the GAN in healthy volunteers and finally performed a retrospective review of patients referred for HRUS examinations because of pain within GAN territory between August 1, 2012 and August 1, 2013. RESULTS: The GAN was clearly visible with HRUS from its formation to the final branches, and was marked successfully on both sides in all anatomical specimens (n = 12). The mean average in-vivo was 0.14 cm ± 0.03 (range 0.08-0.2). Seven cases of patients with GAN pathologies of various origins (idiopathic, traumatic, tumorous and iatrogenic) were identified, of which 6 were visible on HRUS and all of which could be confirmed by complete resolution of symptoms after selective HRUS-guided GAN block. CONCLUSION: This study confirms the reliable ability to visualize the GAN with HRUS throughout its course, both in anatomical specimens and in vivo. The provided cases show that pathologies of the GAN seem to have a variety of causes and may not be rare. We, therefore, encourage the use of HRUS in patients with unclear pain in the auricular, periauricular and posterior-lateral head.

Musculoskeletal ultrasound for peripheral nerve lesions.

Although the combination of a detailed physical examination and a subsequent electrodiagnostic study is used for the diagnosis of peripheral nerve disorders, prompt imaging may also be necessary in daily practice. In this regard, as having higher spatial resolution, and being a faster, more cost-effective and dynamic study; ultrasound (US) has become a very convenient first-line imaging modality for the diagnosis, follow-up and treatment (i.e. guiding interventions or planning for surgery) of peripheral nerve pathologies. Yet, using the probe of US to "sono-auscultate" the peripheral nerves is indisputably paramount for unmasking the whole scenario of injury. Likewise, in this review, we will try to exemplify the role of US for the diagnosis and follow-up of peripheral nerve disorders in clinical practice.

Neurolymphomatosis--diagnosis and assessment of treatment response by FDG PET-CT.

Neurolymphomatosis (NL) is lymphomatous infiltration of peripheral nerves, and is an uncommon manifestation of non-Hodgkin's lymphoma (NHL). Although nerve biopsy is the main method for histological diagnosis, a blind nerve biopsy may not be diagnostic. While CT and MRI have been used to detect NL, recent reports demonstrated the benefit of integrated positron emission tomography (PET) using F18-2-fluoro-2-deoxy-D-glucose (FDG) combined with computed tomography (CT). We described the utility of FDG PET-CT in this uncommon subgroup of NHL where it can assist in establishing the diagnosis, the potential to guide sites for biopsy and in the assessment of response to therapy.

Value of PET in the assessment of patients with neurofibromatosis type 1.

OBJECTIVE: The objective of our study was to investigate the use of PET in the detection of malignant peripheral nerve sheath tumors (MPNSTs) in patients with neurofibromatosis type 1 (NF1). MATERIALS AND METHODS: Forty-five patients with NF1 who underwent whole-body PET for suspected MPNST based on clinical symptoms or radiologic examinations were retrospectively evaluated. Ten patients underwent additional carbon-11 (11C) methionine PET because of equivocal 18F-FDG PET findings or because of a discrepancy between the FDG PET and clinical findings. PET images were evaluated for the distribution and uptake pattern, and the standardized uptake values (SUVs) were obtained. Twenty-seven patients underwent biopsy or surgery of the detected lesions and 18 patients were followed up clinically and with repeat imaging studies. RESULTS: Fifty lesions were identified on FDG PET. There were eight false-positive results and one false-negative on FDG PET. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FDG PET in detecting MPNSTs in patients with NF1 were 95%, 72%, 71%, 95%, and 82%, respectively. Using 11C methionine PET in combination with FDG PET reduced the number of false-positive results from eight to two, which increased the specificity from 72% to 91%. In five patients, 11C methionine FDG PET contributed additional information about nontarget lesions that influenced treatment planning. CONCLUSION: FDG PET is a sensitive technique in the detection of MPNSTs in patients with NF1. The addition of 11C methionine PET increases specificity in equivocal cases. PET may improve preoperative tumor staging by detecting metastases or second primary tumors, which often are present in patients with NF1.

Role of sonography in the preoperative assessment of neurilemmoma.

This case report illustrates the role of high-resolution sonography in the preoperative assessment of a neurilemmoma of the median nerve in the forearm. Sonography identified the 3-dimensional localization of the nerve tumor its origin from a nerve fascicle, and its relationship with noninvolved nerve fascicles, facilitating the surgeon's approach to preserve noninvolved fascicles.