Fusion of positron emission tomography/computed tomography with magnetic resonance imaging reveals hamstring peritendonitis in polymyalgia rheumatica.

Objectives: To characterize 18F-fluorodeoxyglucose (18F-FDG) uptake on whole-body PET/CT in PMR, and identify its precise anatomic correlate using MRI. Methods: Patients with newly diagnosed PMR according to the 2012 EULAR/ACR classification criteria were prospectively recruited. Participants with GCA were excluded. A whole-body 18F-FDG PET/CT scan was performed in all untreated patients. Qualitative and semiquantitative [standardized uptake value maximum (SUVmax)] scoring of abnormal 18F-FDG uptake was undertaken. MRI of the pelvis, knee and wrist and hand was performed in three representative patients with anatomical correlation of FDG-avid sites carried out using Medview fusion software. Results: Twenty-two patients with PMR were recruited. Their mean age was 68.3 years (s.d. 6.3) and 13/22 were male. On whole-body PET/CT, 18F-FDG uptake adjacent to the ischial tuberosities was observed in 21 participants (95.4%) and recorded the highest mean SUVmax value [3.6 (s.d. 1.7)]. A high frequency of posteromedial knee (61.9%) and wrist and/or hand involvement (66.7%) was also appreciated. MRI of the pelvis revealed high T2 signal surrounding the proximal hamstring tendon origins of both semimembranosus and the conjoint tendon of the semitendinosus and biceps femoris. At the knee, peritendonitis at the distal insertion of the semimembranosus was observed. PET/MRI fusion at the pelvis and knee confirmed semimembranosus peritendonitis as the anatomical correlate of 18F-FDG uptake adjacent to the ischial tuberosities and of posteromedial knee structures. Conclusion: Hamstring peritendonitis is a common and distinctive manifestation of PMR on whole-body PET/CT. Trial registration: Australian New Zealand Clinical Trials Registry, http://www.anzctr.org.au, ACTRN1261400696695.

Combined use of iterative reconstruction and monochromatic imaging in spinal fusion CT images.

BACKGROUND: Spinal fusion surgery is an important procedure for treating spinal diseases and computed tomography (CT) is a critical tool for postoperative evaluation. However, CT image quality is considerably impaired by metal artifacts and image noise. PURPOSE: To explore whether metal artifacts and image noise can be reduced by combining two technologies, adaptive statistical iterative reconstruction (ASIR) and monochromatic imaging generated by gemstone spectral imaging (GSI) dual-energy CT. MATERIAL AND METHODS: A total of 51 patients with 318 spinal pedicle screws were prospectively scanned by dual-energy CT using fast kV-switching GSI between 80 and 140 kVp. Monochromatic GSI images at 110 keV were reconstructed either without or with various levels of ASIR (30%, 50%, 70%, and 100%). The quality of five sets of images was objectively and subjectively assessed. RESULTS: With objective image quality assessment, metal artifacts decreased when increasing levels of ASIR were applied (P < 0.001). Moreover, adding ASIR to GSI also decreased image noise (P < 0.001) and improved the signal-to-noise ratio (P < 0.001). The subjective image quality analysis showed good inter-reader concordance, with intra-class correlation coefficients between 0.89 and 0.99. The visualization of peri-implant soft tissue was improved at higher ASIR levels (P < 0.001). CONCLUSION: Combined use of ASIR and GSI decreased image noise and improved image quality in post-spinal fusion CT scans. Optimal results were achieved with ASIR levels ≥70%.

Design of a conformationally defined and proteolytically stable circular mimetic of brain-derived neurotrophic factor.

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of neurotrophic factors. BDNF has long been recognized to have potential for the treatment of a variety of human neurodegenerative diseases. However, clinical trials with recombinant BDNF have yet to yield success, leading to the suggestion that alternative means of harnessing BDNF actions for therapeutic use may be required. Here we describe an approach to create low molecular weight peptides that, like BDNF, promote neuronal survival. The peptides were designed to mimic a cationic tripeptide sequence in loop 4 of BDNF shown in previous studies to contribute to the binding of BDNF to the common neurotrophin receptor p75NTR. The best of these peptides, the cyclic pentapeptide 2 (cyclo(-D-Pro-Ala-Lys-Arg-)), despite being of low molecular weight (Mr 580), was found to be an effective promoter of the survival of embryonic chick dorsal root ganglion sensory neurons in vitro (maximal survival, 68 +/- 3% of neurons supported by BDNF). Pentapeptide 2 did not affect the phosphorylation of either TrkB (the receptor tyrosine kinase for BDNF) or the downstream signaling molecule MAPK, indicating that its mechanism of neuronal survival action is independent of TrkB. NMR studies reveal that pentapeptide 2 adopts a well defined backbone conformation in solution. Furthermore, pentapeptide 2 was found to be effectively resistant to proteolysis when incubated in a solution of rat plasma in vitro. These properties of pentapeptide 2 (low molecular weight, appropriate pharmacological actions, a well defined solution conformation, and proteolytic stability) render it worthy of further investigation, either as a template for the further design of neuronal survival promoting agents or as a lead compound with therapeutic potential in its own right.

Utility of musculoskeletal ultrasound.

A 37 year old runner presents with multiple aches and pains in the lower limb and foot with the most focal being swelling and tenderness in his Achilles tendon, most often after a workout. You are wondering how best to image his pathology.