Christopher Pivec

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.

High‐resolution ultrasound visualization of the subcutaneous nerves of the forearm: A feasibility study in anatomic specimens

Introduction: The aim of this ultrasound‐anatomical study was to evaluate the ability of high‐resolution ultrasound (HRUS) to visualize and infiltrate small subcutaneous nerves of the forearm in anatomic specimens. Methods: Seven nonembalmed human bodies (4 men, 3 women; mean age at death, 60 years) were included in the study. Two investigators scanned the anatomic specimens using 15‐MHz and 18‐MHz HRUS transducers. The lateral, medial, and posterior antebrachial cutaneous nerves were scanned and interventionally marked with ink using HRUS‐guidance. Subsequently, dissections were performed to assess the anatomical correlation of HRUS findings. Results: All 3 nerves were identified consistently using HRUS. The precision of the ink‐markings was excellent, with good correlation with the small peripheral branches of all 3 nerves. Conclusions: HRUS can identify precisely the small subcutaneous nerves of the forearm and may aid in both diagnosis and therapy in cases of neuropathy. Muscle Nerve 49: 676–679, 2014

Unusual Cause of Anterior Tarsal Tunnel Syndrome: Ultrasound Findings

We describe a unique case of a trauma-induced deep peroneal intraneural ganglion emerging from the ankle joint causing anterior tarsal tunnel syndrome that was diagnosed and to our knowledge treated for the first time with the help of ultrasound imaging. A 51-year-old woman presented with swelling and pain in the area of the left anterior shin and dorsum of the foot. The patient had sustained a lateral inversion injury of her left ankle 6 months earlier. After the trauma, a slowly growing swelling appeared around the lateral malleolus. In the following 3 months, she also developed paresthesia at the dorsum of the foot and pain at the anterior shin. She was not able to wear tight shoes or shoes with laces, nor could she tolerate even a slightest touch in the affected region. Clinical examination showed a nontender swelling at the left lateral malleolus, numbness between the first and second toes, and weakness in extending the first toe. Conventional x-ray images of the foot and ankle revealed no bony abnormalities. Magnetic resonance imaging (1.5 Tesla) of the ankle showed only a small cyst emerging behind the fibula from the ankle joint, but no other abnormalities. Thereafter, she underwent an ultrasound investigation to rule out muscle tear, chronic compartment syndrome, or deep venous thrombosis. The ultrasound investigation revealed an anechoic cystic lesion within the deep peroneal nerve measuring 7 mm in transverse diameter and 11 mm in length at the level of the extensor retinaculum. It displaced the nerve fascicles inside the nerve more peripherally and closer to the inner side of the nerve sheath (Figure 1). More distally, the cystic lesion extended laterally over the fibula and connected to a ganglion emerging from the ankle joint (Figure 2). Within this cystic extension was a small tubular structure suggestive of an articular nerve branch. All of this led to the diagnosis of an intraneural ganglion of the deep peroneal nerve. After obtaining the patient’s written informed consent, the patient underwent ultrasound-guided fine-needle aspiration of the deep peroneal nerve ganglion, and 1 mL of viscous fluid was aspirated (Figure 3) that laboratory analysis later confirmed to be synovial fluid. In addition, the nerve sheath of the articular branch was dry-needled to avoid refilling of the nerve sheath ganglion. The patient’s symptoms disappeared within 1 week after the procedure. Moreover, a follow-up ultrasound indicated that the ganglion within the deep peroneal nerve did not recur. However, during the following 3 months, the ganglion more laterally near the joint significantly increased in size, and surgical resection of the ganglion without articular nerve dissection was performed. The patient has remained symptom-free for 1 year now. Anterior tarsal tunnel syndrome is a rare condition characterized by compression of the deep peroneal nerve at the level of the extensor retinaculum. Direct trauma, repetitive mechanical irritation, and compression by ganglia are the most common causes of this type of neuropathy.

Influence of PET reconstruction technique and matrix size on qualitative and quantitative assessment of lung lesions on [18F]-FDG-PET: A prospective study in 37 cancer patients

PURPOSE To evaluate the influence of point spread function (PSF)-based reconstruction and matrix size for PET on (1) lung lesion detection and (2) standardized uptake values (SUV). METHODS This prospective study included oncological patients who underwent [18F]-FDG-PET/CT for staging. PET data were reconstructed with a 2D ordered subset expectation maximization (OSEM) algorithm, and a 2D PSF-based algorithm (TrueX), separately with two matrix sizes (168×168 and 336×336). The four PET reconstructions (TrueX-168; OSEM-168; TrueX-336; and OSEM-336) were read independently by two raters, and PET-positive lung lesions were recorded. Blinded to the PET findings, a third independent rater assessed lung lesions with diameters of >4mm on CT. Subsequently, PET and CT were reviewed side-by side in consensus. Multi-factorial logistic regression analyses and two-way repeated measures analyses of variance (ANOVA) were performed. RESULTS Thirty-seven patients with 206 lung lesions were included. Lesion-based PET sensitivities differed significantly between reconstruction algorithms (P<0.001) and between reconstruction matrices (P=0.022). Sensitivities were 94.2% and 88.3% for TrueX-336; 88.3% and 85.9% for TrueX-168; 67.8% and 66.3% for OSEM-336; and 67.0% and 67.9% for OSEM-168; for rater 1 and rater 2, respectively. SUVmax and SUVmean were significantly higher for images reconstructed with 336×336 matrices than for those reconstructed with 168×168 matrices (P<0.001). CONCLUSION Our results demonstrate that PSF-based PET reconstruction, and, to a lesser degree, higher matrix size, improve detection of metabolically active lung lesions. However, PSF-based PET reconstructions and larger matrix sizes lead to higher SUVs, which may be a concern when PET data from different institutions are compared.

The lesser occipital nerve visualized by high-resolution sonography—normal and initial suspect findings:

Background The lesser occipital nerve (LON) supplies the lateral part of the occiput and is—together with the greater occipital nerve (GON)—involved in headache pathogenesis. While the GON was described in high-resolution ultrasound (HRUS), the same does not apply to the LON. We aimed at characterizing the LON in HRUS, and present cases of suspect findings in the course of the LON identified by HRUS. Methods The LON was examined bilaterally in eight anatomical specimens with HRUS (n = 16). HRUS-guided ink marking and consecutive dissection was performed. Further, measurements of the LON diameter were performed in 10 healthy volunteers (n = 20), and patient charts were reviewed to identify patients who were considered to have possible pathology of the LON. Results The LON was identified correctly in all cadavers on both sides and all volunteers except for one side (n = 19). The average diameter was 1.08 ± 0.30 mm. Four patients with pain within the LON territory and presumed peripheral origin of headache (defined as resolution of headache after diagnostic HRUS-guided selective blockade) were identified, and three of these showed interference of the LON with lymph nodes or an accessory muscle belly. Discussion We confirm the possibility of visualization of the LON using HRUS. HRUS may be a helpful adjunct tool in the assessment of patients with atypical headache.

High-Resolution Ultrasound Visualization of Pacinian Corpuscles

The aim of this study was to evaluate the possibility of visualizing Pacinian corpuscles in the palm of the hand with high-resolution ultrasound (HRUS). In this prospective study, HRUS with a high-frequency probe (22 MHz) was used. The palms of two fresh cadaveric hands were screened for potential Pacinian corpuscles. Still ultrasound images and dynamic video sequences were obtained. In five regions with large amounts of suspected Pacinian corpuscles, tissue blocks were excised and histologically processed, and corresponding slices were compared with ultrasound images. Further, the transverse diameters of five Pacinian corpuscles, at the level of the metacarpal heads in the palm, were assessed on both sides (in total 100) in healthy volunteers. On ultrasound, Pacinian corpuscles presented as echolucent dots in the subcutis, adjacent to digital nerves and vessels and located 2-3 mm beneath the surface. On histologic sections, these echolucent dots corresponded to Pacinian corpuscles with respect to their position and topographic relationships. The mean transverse diameter for all volunteers was 1.40 ± 0.23 mm (range: 0.8-2.2 mm). This study confirms the ability to reliably visualize Pacinian corpuscles with HRUS, which contributes to our basic understanding of ultrasonographically visible subcutaneous structures and may enhance the diagnosis of pathologies related to Pacinian corpuscles.

Novel Demonstration of the Anterior Femoral Cutaneous Nerves using Ultrasound

PURPOSE  Neuropathy of the intermediate (IFCN) and medial femoral cutaneous nerve (MFCN) is a potential iatrogenic complication of thigh surgery and its diagnosis is limited. This study aimed to evaluate the possibility of the visualization and diagnostic assessment of the IFCN and MFCN with high-resolution ultrasound (HRUS). MATERIALS AND METHODS  In this study, HRUS with high-frequency probes (15 - 22MHz) was used to locate the IFCN and the MFCN in 16 fresh cadaveric lower limbs. The correct identification of the nerves was verified by ink-marking and consecutive dissections at sites correlating to nerve positions (R1 - 3), namely, the origin, the mid portion, and the distal portion, respectively. 12 cases with suspected IFCN and MFCN lesions referred to our clinic for HRUS examinations were also assessed. RESULTS  Anatomical dissection confirmed the correct identification of the IFCN in 16/16 branches at all of the different locations (100 %). MFCN was correctly identified at R1 + 3, in all cases (16/16; 100 %), and in 14/16 cases (88 %) at (R2). 12 cases of patients with IFCN and MFCN pathologies (all of iatrogenic origin) were identified. 9 instances of structural damage were visible on HRUS, and all pathologies were confirmed by almost complete resolution of symptoms after selective HRUS-guided blocks with 0.5 - 1 ml lidocaine 2 %. CONCLUSION  This study confirms that the IFCN and the MFCN can be reliably visualized with HRUS throughout the course of these nerves, both in anatomical specimens and in patients.

A Rare Case of Guyon's Canal Syndrome Caused by Cystic Adventitia Degeneration: High-Resolution Ultrasound Findings

Entrapment of the ulnar nerve inside the ulnar tunnel, which is also called Guyon’s canal, is a well-known entity leading to pain, numbness and loss of function in the part of the hand supplied by the ulnar nerve. Space-occupying lesions in this area, such as ganglions, tendinitis, fracture, arthritis, nonspecific edema and thromboangitis, may cause the entrapment of the nerve, known as ulnar tunnel syndrome. Cystic adventitial disease (CAD) is a rare benign vascular lesion, where cysts form in the adventitia of a blood vessel, first described in the iliac artery (Atkins HJ, Key JA. Br J Surg 1947; 34: 426). CADmay cause local pain due to the stenosis and occlusion of the vessel and can be treated either with USor CT-guided percutaneous cyst aspiration or surgery (Drac P et al. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2011; 155: 309 – 321). For unknown reasons, most of the CAD cases reported thus far involve the popliteal artery in young middle-aged men (Drac P et al. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2011; 155:309 – 321). A few cases have also been described in the external iliac, common femoral, axillary, distal brachial, and radial arteries. Although the pathomechanisms of CAD remain controversial, a theory of joint-related origin has been suggested, similar to the pathogenesis of intraneural ganglion cysts (Spinner RJ et al. Clin Anat 2013; 26: 267 – 281). The diagnosis can be established with high-resolution ultrasound and MRA as the first-choice imaging methods (Drac P et al. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2011; 155: 309 – 321). We report here a unique case of cystic adventitial degeneration that affected the ulnar artery and caused ulnar nerve palsy, which was detected with high-resolution ultrasound. Case Presentation

High-resolution ultrasound visualization of the deep branch of the ulnar nerve

Introduction: The value of imaging the deep branch of the ulnar nerve (DBUN) over its entire course has not been clarified. Therefore, this study evaluates the feasibility of visualizing the DBUN from its origin to the most distal point. Methods: We performed high‐resolution ultrasound (HRUS) with high‐frequency probes (18–22 MHZ), HRUS‐guided ink marking, and consecutive dissection in 8 fresh cadaver hands. In both hands of 10 healthy volunteers (n = 20), the cross‐sectional area (CSA) was measured at 2 different locations (R1 and R2). Results: The DBUN was clearly visible in all anatomical specimens and in healthy volunteers. Dissection confirmed HRUS findings in all anatomical specimens. The mean CSA was 1.8 ± 0.5 mm2 at R1 and 1.6 ± 0.4 mm2 at R2. Discussion: This study confirms that the DBUN can be reliably visualized over its entire course with HRUS in anatomical specimens and in healthy volunteers. Muscle Nerve 56: 1101–1107, 2017