High-resolution ultrasound of the paratenon of the Achilles calcaneal tendon: anatomical study and description of the paratendinous injection technique.

PURPOSE: The aim of this study is to determine if ultrasound (US) allows a precise assessment of the paratenon (PT) of the Achilles calcaneal tendon (AT), and to anatomically describe the US-guided paratendinous injection technique. METHODS: This study was initially conducted on eight cadaveric specimens using high-resolution ultrasound (HRUS) to examine the PT appearance, thickness, and its relationships with the AT, plantaris tendon (PLT), Kager's fat pad (KFP), sural nerve (SN), and fascia cruris (FC). US-guided paratendinous injection of China ink was performed in all specimens, followed by anatomical dissection to assess injectate distribution. Then, HRUS study of the PT was carried out bilaterally in twenty asymptomatic volunteers (40 legs). Two musculoskeletal radiologists recorded all data in consensus except PT thickness in volunteers which was recorded independently in order to calculate intra and inter-observer reliability. RESULTS: The PT was consistently identified with HRUS along its entire course in both cadaveric specimens (8/8) and volunteers (40/40). The mean PT thickness was 0.54 mm in cadavers and 0.39 mm in vivo, without any correlation with the AT thickness. Intra- and inter observer reliability were respectively excellent and good for PT thickness. All eight (100%) ex vivo China ink injections were accurate, demonstrating a circumferential distribution of the injectate between the PT and the AT, associated with an anterior spread to the KFP. CONCLUSION: HRUS allows visualization of the PT along its entire length, and assessment of its relationships to adjacent structures. US-guided paratendinous injections can accurately and safely deliver injectates in the paratendinous sheath.

Anatomical study of the medial calcaneal nerve using high-resolution ultrasound.

OBJECTIVES: To determine whether high-resolution ultrasound (US) can identify the course and relations of the medial calcaneal nerve (MCN). METHODS: This investigation was initially undertaken in eight cadaveric specimens and followed by a high-resolution US study in 20 healthy adult volunteers (40 nerves) by two musculoskeletal radiologists in consensus. The location and course of the MCN as well as its relationship to adjacent anatomical structures were evaluated. RESULTS: The MCN was consistently identified by US along its entire course. The mean cross-sectional area of the nerve was 1 mm2 (range 0.5-2). The level at which the MCN branched from the tibial nerve was variable, located a mean of 7 mm (range - 7-60) proximal to the tip of the medial malleolus. At the level of the medial retromalleolar fossa, the MCN was located inside the proximal tarsal tunnel a mean of 8 mm (range 0-16) posterior to the medial malleolus. More distally, the nerve was depicted in the subcutaneous tissue at the surface of the abductor hallucis fascia with a mean direct distance to the fascia of 1.5 mm (range 0.4-2.8). CONCLUSIONS: High-resolution US can identify the MCN at the level of the medial retromalleolar fossa, as well as more distally in the subcutaneous tissue at the surface of the abductor hallucis fascia. In the setting of heel pain, precise sonographic mapping of the MCN course may enable the radiologist to make diagnosis of nerve compression or neuroma, and perform selective US-guided treatments. CLINICAL RELEVANCE STATEMENT: In the setting of heel pain, sonography is an attractive tool for diagnosing compression neuropathy or neuroma of the medial calcaneal nerve, and enables the radiologist to perform selective image-guided treatments such as diagnostic blocks and injections. KEY POINTS: • The MCN is a small cutaneous nerve which rises from the tibial nerve in the medial retromalleolar fossa to the medial side of the heel. • The MCN can be depicted by high-resolution ultrasound along its entire course. • In the setting of heel pain, precise sonographic mapping of the MCN course may enable the radiologist to make diagnosis of neuroma or nerve entrapment, and perform selective ultrasound-guided treatments such as steroid injection or tarsal tunnel release.

Ultrasound and MR imaging of peripheral nerve tumors: the state of the art.

Peripheral nerve sheath tumors are a heterogeneous subgroup of soft tissue tumors that either arise from a peripheral nerve or show nerve sheath differentiation. On imaging, direct continuity with a neural structure or location along a typical nerve distribution represents the most important signs to suggest the diagnosis. Ultrasound and magnetic resonance imaging are the best modalities to evaluate these lesions. First, it is necessary to differentiate between a true tumor and a non-neoplastic nerve condition such as a neuroma, peripheral nerve ganglion, intraneural venous malformation, lipomatosis of nerve, or nerve focal hypertrophy. Then, with a combination of clinical features, conventional and advanced imaging appearances, it is usually possible to characterize neurogenic tumors confidently. This article reviews the features of benign and malignant peripheral nerve sheath tumors, including the rare and recently described tumor types. Furthermore, other malignant neoplasms of peripheral nerves as well as non-neoplastic conditions than can mimick neurogenic tumor are herein discussed.

Osteoid Osteoma: Percutaneous CT-guided Cryoablation Is a Safe, Effective, and Durable Treatment Option in Adults.

Background Cryoablation is playing an increasing role in the percutaneous treatment of bone tumors. However, despite its potential advantages over heat-based ablation techniques, the clinical safety and efficacy of cryoablation have not been established for osteoid osteoma treatment. Purpose To evaluate percutaneous CT-guided cryoablation for the treatment of osteoid osteoma in young patients and adults. Materials and Methods This retrospective study reviewed data from 50 consecutive patients who underwent percutaneous CT-guided cryoablation for the treatment of osteoid osteoma between January 2013 and June 2019 in a single institution. In 30 of 50 patients (60%), the procedure was carried out with the patient under local anesthesia and conscious sedation, with the cryoprobe covering the lesion from an extraosseous position, avoiding direct penetration of the nidus. Clinical and radiologic features, procedure-related data, visual analog scale (VAS) pain scores, complications, and overall success rate were evaluated. Statistical analyses were performed by using the nonparametric Friedman test and Wilcoxon signed rank test for repeated measures. Results Fifty patients (median age, 24 years; interquartile range [IQR], 19-38 years; 31 men) underwent CT-guided cryoablation for the treatment of osteoid osteoma, with a 96% (48 of 50 patients) overall clinical success rate. Of the two patients without clinical success, one patient had incomplete pain relief and the other experienced a recurrence of osteoid osteoma at 11 months, which was successfully treated with a second cryoablation procedure. The median VAS pain score was 8 (IQR, 7-8) before the procedure and 0 (IQR, 0-1; P < .001) after the procedure at both primary (6 weeks) and secondary (18-90 months) follow-up. Three of the 50 patients had minor complications (6%); no major complications were reported. Conclusion Osteoid osteoma was safely, effectively, and durably treated with CT-guided percutaneous cryoablation. In the majority of patients, treatment could be performed without general anesthesia, with the cryosphere covering the nidus from an extraosseous position. © RSNA, 2021.

Shoulder palsy following SARS-CoV-2 infection: two cases of typical Parsonage-Turner syndrome.

BACKGROUND AND PURPOSE: Coronavirus disease 2019 (COVID-19) is now known to cause neurological complications in both the central and the peripheral nervous system. Two new cases of typical neuralgic amyotrophy or Parsonage-Turner (PT) syndrome following coronavirus 2 infection (SARS-CoV-2) are reported here with explicit electrophysiological and imaging pathological features, underlining the possible association between COVID-19 and PT syndrome. CASE REPORTS: Case 1 was a 45-year-old schoolteacher presenting with acute pain in the right shoulder a few days after SARS-CoV-2 infection, with shoulder abduction and elbow flexion weakness. Needle electromyography showed a decrease in motor unit recruitment in the biceps brachii, and plexus magnetic resonance imaging (MRI) revealed a hyperintense signal involving the right C6 root and the superior truncus of the brachial plexus. Case 2 was a 21-year-old man hospitalized for dyspnea secondary to SARS-CoV-2 infection. Ten days after symptom onset, he presented right shoulder pain with difficulty in raising his right arm, revealing an isolated deficit of the serratus major muscle with a right scapula winging. Electrophysiological evaluation exhibited an isolated involvement of the long thoracic nerve with a neurogenic recruitment pattern in the serratus major muscle. Plexus MRI displayed a thickening and hyperintense signal involving the right long thoracic nerve. DISCUSSION: Parsonage-Turner syndrome triggered by SARS-CoV-2 seems to present clinical, electrophysiological and MRI characteristics similar to classic para-infectious PT syndrome, including the time frame between viral infection and neurological symptom onset. Conclusion SARS-CoV-2 might be a new infectious trigger of PT syndrome.

Ultrasound-Guided Perimeniscal Injections: Anatomical Description and Feasibility Study.

OBJECTIVES: To anatomically describe the ultrasound (US)-guided perimeniscal injection technique, and evaluate its feasibility in the treatment of meniscal pain. METHODS: This work was initially undertaken in four cadaveric specimens with US-guided medial and lateral perimeniscal injection of China ink, followed by cadaveric dissection to assess injectate distribution, and potential injury to intra-articular and peri-articular structures. Then, 35 consecutive patients who underwent US-guided perimeniscal corticosteroid injection under local anesthesia for the treatment of symptomatic medial (30/35) or lateral (5/35) degenerative meniscal tear were retrospectively evaluated. Clinical outcome was assessed using a 0-10 numerical verbal rating scale (VRS) to evaluate severity of pain before, during, and after procedure at 6 weeks follow-up. RESULTS: Seven of eight (87.5%) ex vivo injections were accurate. A single inaccurate medial perimeniscal injection infiltrated the tibial collateral ligament instead of the perimeniscal area. No anatomical specimen exhibited intrameniscal injection or injury to regional structures. All procedures (35/35) performed clinically were technically successful. Median VRS scores were: 7 (range, 3-9) before procedure, 5 (range, 0-10) during procedure, and 1.5 (range, 0-9) after procedure at 6 weeks follow-up (P <.0001). No complication was observed. CONCLUSIONS: US-guided perimeniscal injections can accurately and safely deliver injectates in the perimeniscal area. In addition, our data suggest that perimeniscal corticosteroid injection provides significant symptom relief at 6 weeks in patients with meniscal pain. Further studies with long-term follow-up will be required to evaluate the role of perimeniscal injections in the nonoperative management of meniscal pathology.

Intradiscal oxygen-ozone therapy for the treatment of symptomatic lumbar disc herniation: A preliminary study.

PURPOSE: To assess safety and effectiveness of computed tomography (CT)-guided intradiscal oxygen-ozone therapy (O2-O3 therapy) for the treatment of symptomatic lumbar disc herniation and radiological changes. MATERIALS AND METHODS: This study was conducted in twenty patients presenting lumbar disc herniation with resistant lumbar or lumbar radicular pain They underwent intradiscal oxygen-ozone therapy under CT guidance. They were treated at one- or two-disc levels, representing a total of 24 discs treated. MR imaging examinations were obtained before treatment and 2 months post-procedure to analyse treatment-related disc modifications including modification of the surfaces of the disc and of the herniated disc, and the variations in disc height according to the disc height index. Clinical outcomes were assessed using the visual analogue scale (VAS) to evaluate the severity of pain before the procedure, at primary (2 months) and at secondary (12 months) follow-ups. RESULTS: All the procedures were technically successful. The median VAS scores were 7.95 before the procedure, 3.9 at 2 months and 2.95 at 12 months. MRI analysis showed a significant decrease in herniation size at 2 months (-20%, p = 0.008). No immediate or late complications were observed. Only three patients (13.6%) underwent lumbar spine microdiscectomy in the year following ozone therapy. The treatment appeared to be more effective in cases of nerve root symptomatology. CONCLUSION: This study suggests that intradiscal O2-O3 therapy is safe and effective for the treatment of lumbar disc herniation associated with resistant lumbar or lumbar radicular pain.

Stenosing tenosynovitis of the extensor digitorum tendons of the hand: clinical and sonographic features.

OBJECTIVE: To describe the ultrasound (US) features of 18 patients with extensor digitorum communis stenosing tenosynovitis (EDCST). MATERIALS AND METHODS: A retrospective search in the radiologic information systems of two separate Institutions was performed to identify all patients presenting EDCST between January 2010 and September 2019. A total of 18 patients (ten males and eight females; mean age, 57.4 years) were identified and included. Sonographic examinations were retrospectively reviewed by two senior radiologists to assess morphologic changes and power Doppler activity of the extensor retinaculum (ER) and of the extensor digitorum communis (EDC) tendons and sheath. The presence of dynamic impingement between the EDC and the ER was evaluated using video clip records. RESULTS: At the ultrasound, all patients (18/18; 100%) presented thickening of both the ER and EDC tendons associated with EDC tendon sheath effusion. Power Doppler hyperemia of the ER was inconstant and observed in 11 cases (11/18; 61.1%) as tendon sheath effusion observed in 16 cases (16/18; 88.9%). A cyst located inside the EDC of the index finger was observed in three of these patients (3/18; 17%). Dynamic examination showed impingement of the EDC against the ER during active tendon extension in all patients (18/18; 100%). Four of these patients (4/18; 22%) underwent surgery allowing diagnosis confirmation and release of EDCST, while the remaining fourteen patients (14/18; 78%) were either treated conservatively or using US-guided steroid injection. CONCLUSION: US findings of EDCST include thickening of the ER and EDC tendons, EDC tendon sheath effusion, and in some cases presence of an EDC intratendinous cyst. Impingement of the EDC tendons against the ER is well demonstrated using dynamic US.

Acral FibroChondroMyxoid tumor: imaging features of a new entity.

"Acral FibroChondroMyxoid tumor" (AFCMT) is a recently described distinctive subtype of acral soft tissue tumor that typically arises on the fingers and toes. We herein present the unreported imaging features of AFCMT in a 44-year-old woman. This otherwise healthy patient was referred for a painful, slow-growing, soft tissue mass in the middle finger of her right hand. Initial radiographs and computed tomography showed a small lesion centered in the soft tissue of the ulnar aspect of the proximal phalanx, associated with scalloping of the underlying bone. Magnetic resonance imaging confirmed the presence of a well-circumscribed soft tissue tumor that exhibited relatively high T2-weighted signal intensity and marked enhancement after contrast administration. Subsequent excisional biopsy was performed. Histologically, the tumor was characterized by an abundant stroma displaying fibrous, chondroid, and myxoid areas. By immunohistochemistry, tumor cells stained for CD34, ERG, and focally S100 protein. RNA-sequencing allowed detection of THBS1-ADGFR5 gene fusion which confirmed the diagnosis of AFCMT. At 2-year follow-up, the patient remains free of recurrence. AFCMT is a previously unrecognized entity that may mimic chondroma and should be considered in the differential diagnosis of soft tissue tumors with cartilaginous or myxoid stroma in the extremities.

Comparison of MRI and motor evoked potential with triple stimulation technique for the detection of brachial plexus abnormalities in multifocal motor neuropathy.

BACKGROUND: Conduction blocks (CB) are the diagnostic hallmark of multifocal motor neuropathy (MMN). Conventional nerve conduction studies cannot detect CB above Erb's point. Our purpose was to compare the performance of the motor evoked potential with triple stimulation technique (MEP-TST) and MRI in the detection of abnormalities of the brachial plexus. METHODS: Examinations were performed on 26 patients with MMN (11 definite, 6 probable, 9 possible), of whom 7 had no CB. RESULTS: MEP-TST detected proximal CB in 19/26 patients. Plexus MRI showed T2 hyperintensity in 18/26 patients, with nerve enlargement in 14/18. A combination of both techniques increased the detection rate of brachial plexus abnormalities to 96% of patients (25/26). CONCLUSIONS: MEP-TST and MRI have high sensitivities for detecting brachial plexus abnormalities. A combination of the two techniques increases the detection rate of supportive criteria for the diagnosis of MMN.

Correction to: Flat-panel CT arthrography for cartilage defect detection in the ankle joint: first results in vivo.

The names of the following authors were inadvertently inverted in the original manuscript.

Flat-panel CT arthrography for cartilage defect detection in the ankle joint: first results in vivo.

OBJECTIVES: The purpose of this study was to compare the diagnostic performance of flat-panel computed tomography (FPCT) arthrography for cartilage defect detection in the ankle joint to direct magnetic resonance (MR) arthrography using multidetector computed tomography (MDCT) arthrography as the reference standard. METHODS: Twenty-seven patients with specific suspicion of articular cartilage lesion underwent ankle arthrography with injection of a mixture of diluted gadolinium and iobitridol and were examined consecutively with the use of FPCT, MDCT, and 1.5 T MR imaging. FPCT, MDCT, and MR arthrography examinations were blinded and randomly evaluated by two musculoskeletal radiologists in consensus. In each ankle, eight articular cartilage areas were assessed separately: medial talar surface, medial talar trochlea, lateral talar trochlea, lateral talar surface, tibial malleolus, medial tibial plafond, lateral tibial plafond, and fibular malleolus. Findings at FPCT and MR were compared with MDCT assessments in 216 cartilage areas. RESULTS: For the detection of cartilage defects, FPCT demonstrated a sensitivity of 97%, specificity of 95%, and accuracy of 96%; and MR arthrography showed a sensitivity of 69%, specificity of 94%, and accuracy of 87%. FPCT and MR arthrography presented almost perfect agreement (κ = 0.87) and moderate agreement (κ = 0.60), respectively, with MDCT arthrography. Mean diagnostic confidence was higher for FPCT (2.9/3) than for MR (2.3/3) and MDCT (2.7/3) arthrography. CONCLUSIONS: FPCT demonstrated better accuracy than did 1.5 T MR arthrography for cartilage defect detection in the ankle joint. Therefore, FPCT should be considered in patients scheduled for dedicated imaging of ankle articular cartilage.

Anterolateral knee pain related to thrombosed lateral patellar retinaculum veins: Unusual anterolateral pain of the knee.

We describe the ultrasound (US) features of venous thrombosis involving the lateral patellar retinaculum (LPR) veins presenting as anterolateral knee pain. Four male patients, aged 16 to 35 years, were referred for lateropatellar pain with focal tenderness. In two cases, physical examination also demonstrated soft tissue swelling at the anterolateral aspect of the knee. In all four cases, US showed subcutaneous fat edema surrounding a thrombosis involving the LPR veins. Magnetic resonance imaging performed before US in one patient revealed only nonspecific subcutaneous fat edema and was therefore unable to make the correct diagnosis of LPR venous thrombosis.

Anatomical study of the medial plantar proper digital nerve using ultrasound.

PURPOSE: To determine whether ultrasound allows precise assessment of the course and relations of the medial plantar proper digital nerve (MPPDN). MATERIALS AND METHODS: This work was initially undertaken in six cadaveric specimens and followed by a high-resolution ultrasound study in 17 healthy adult volunteers (34 nerves) by two musculoskeletal radiologists in consensus. Location and course of the MPPDN and its relationship to adjacent anatomical structures were analysed. RESULTS: The MPPDN was consistently identified by ultrasound along its entire course. Mean cross-sectional area of the nerve was 0.8 mm2 (range 0.4-1.4). The MPPDN after it branches from the medial plantar nerve was located a mean of 22 mm (range 19-27) lateral to the medial border of the medial cuneiform. More distally, at the level of the first metatarsophalangeal joint, mean direct distances between the nerve and the first metatarsal head and the medial hallux sesamoid were respectively 3 mm (range 1-8) and 4 mm (range 2-9). CONCLUSION: The MPPDN can be depicted by ultrasonography. Useful bony landmarks for its detection could be defined. Precise mapping of its anatomical course may have important clinical applications. KEY POINTS: • The medial plantar proper digital nerve (MPPDN) rises from the medial plantar nerve to the medial side of the hallux. • Because of its particularly long course and superficial position, the MPPDN may be subject to trauma, resulting in a condition known as Joplin's neuroma. • The MPPDN can be clearly depicted by ultrasound along its entire course. Precise mapping of its anatomical course may have important clinical applications.

The lateral patellar retinaculum defect: anatomical study using ultrasound.

OBJECTIVE: The purpose of this study was to evaluate whether ultrasound allows precise assessment of a focal defect at the lateral patellar retinaculum (LPR) and to determine its anatomical significance. MATERIALS AND METHODS: This work was initially undertaken in four cadaveric specimens and followed by high-resolution ultrasound study in 48 healthy adult volunteers (96 knees) by two musculoskeletal radiologists. Dimension and location of the LPR defect and its relations to adjacent anatomical structures were analyzed. RESULTS: A focal defect of the LPR through which vessels penetrated was constantly identified by ultrasound in our population. The mean transverse diameter of the defect was 2.4 mm (range, 1-6 mm). The defect was located a mean of 23.7 mm (range, 18-30 mm) proximal to the lateral tibial plateau and 6.6 mm (range, 4-9 mm) lateral to the patellar tendon. Anatomical dissection demonstrated that the LPR defect is related to perforating vessels that originate from the peripatellar anastomotic ring. CONCLUSIONS: The focal defect of the LPR can be depicted by ultrasonography. Reproducible anatomical landmarks for its detection could be defined. Our data suggest the LPR defect may be considered a normal variant rather than a pathologic change.

Partial anterior tunnel syndrome: a retrospective analysis of ultrasound findings in four surgically proven cases.

We present the cases of four patients (two men and two women, mean age of 48.5 years) with surgically confirmed partial anterior tarsal syndrome, diagnosed by ultrasound. All patients reported pain in the dorsal aspect of the forefoot radiating to the first intermetatarsal space. Ultrasound showed compression of the medial branch of the deep fibular nerve by the extensor hallucis brevis tendon at the level of the Lisfranc joint, associated with a hypoechoic neuroma. The ultrasound allowed a correct diagnosis to be obtained, which was not evident from clinical examination or by standard radiographs (four patients) or MRI (three patients). Surgery confirmed the sonographic findings, and all patients showed complete recovery.

Percutaneous cryoablation for the treatment of osteoid osteoma in the adult population.

PURPOSE: To evaluate the technical feasibility and efficacy of percutaneous cryoablation for the treatment of osteoid osteoma (OO) in adults. METHODS AND MATERIALS: 21 patients (12 male and nine female; mean age, 29.9 years) who underwent CT-guided percutaneous cryoablation for the treatment of OO were retrospectively evaluated. Procedures were carried out under local anaesthesia and conscious sedation in 13 patients, and under general anaesthesia in eight patients. Then, the ablation zone was evaluated with post-procedure magnetic resonance imaging at 6 weeks. Clinical outcome was assessed using a visual analogue scale (VAS) to evaluate severity of pain before procedure, as well as at primary (6 weeks) and secondary follow-up (6-40 months). RESULTS: All procedures were technically successful. Median VAS scores were: 8 (range, 5-10) before procedure and after procedure, respectively, 0 (range, 0-2; p < .0001) and 0 (range, 0-7; p < .0001) at primary and secondary follow-up. There were three minor complications (14.3%) and no major complication. A single patient reported symptom recurrence (4.8%) at secondary follow-up and successfully underwent a second cryoablation procedure. CONCLUSION: CT-guided percutaneous cryoablation is safe and effective in the treatment of OO in adults, and can be accomplished without general anaesthesia in selected cases. KEY POINTS: • CT-guided percutaneous cryoablation of osteoid osteoma is safe and effective • Cryoablation allows precise visual control of the aggregated iceball during procedure • Percutaneous cryoablation can be accomplished without general anaesthesia in selected cases • Another advantage of cryoablation is reduction of immediate postprocedural pain • Post-procedure MRI is helpful in the evaluation of technical success.

Soft Tissue Masses of the Knee Related to a Focal Defect of the Lateral Patellar Retinaculum.

We report on the imaging features of 6 soft tissue masses in the anterolateral aspect of the knee related to a focal defect of the lateral patellar retinaculum. In 4 patients (3 female and 1 male; 6-65 years) presenting with nontender palpable soft tissue masses in the anterolateral aspect of their knees, ultrasonography showed a focal defect of the lateral patellar retinaculum with herniation of the Hoffa fat pad, which was only visible in flexion. A magnetic resonance imaging examination performed in 1 case confirmed the defect in the lateral patellar retinaculum but did not show a mass, as the knee was examined only at 10° of flexion. The 2 remaining patients (one male and 1 female; 62 and 55 years) presented with soft tissue masses in their anterolateral knees in both flexion and extension. These masses were related respectively to a lipoma of the Hoffa fat pad and to a ganglion cyst, both herniated through a defect of the lateral patellar retinaculum. Our cases suggest that a focal defect of the lateral patellar retinaculum may be a route for Hoffa fat pad herniation as well as a route for superficial extension of infrapatellar fat lesions such as lipomas and ganglion cysts.