Eric Pessis

Virtual Monochromatic Spectral Imaging with Fast Kilovoltage Switching: Reduction of Metal Artifacts at CT

With arthroplasty being increasingly used to relieve joint pain, imaging of patients with metal implants can represent a significant part of the clinical work load in the radiologists daily practice. Computed tomography (CT) plays an important role in the postoperative evaluation of patients who are suspected of having metal prosthesis-related problems such as aseptic loosening, bone resorption or osteolysis, infection, dislocation, metal hardware failure, or periprosthetic bone fracture. Despite advances in detector technology and computer software, artifacts from metal implants can seriously degrade the quality of CT images, sometimes to the point of making them diagnostically unusable. Several factors may help reduce the number and severity of artifacts at multidetector CT, including decreasing the detector collimation and pitch, increasing the kilovolt peak and tube charge, and using appropriate reconstruction algorithms and section thickness. More recently, dual-energy CT has been proposed as a means of reducing beam-hardening artifacts. The use of dual-energy CT scanners allows the synthesis of virtual monochromatic spectral (VMS) images. Monochromatic images depict how the imaged object would look if the x-ray source produced x-ray photons at only a single energy level. For this reason, VMS imaging is expected to provide improved image quality by reducing beam-hardening artifacts.

Sonographic Appearance of Trigger Fingers

Objective. The purpose of this study was to describe the sonographic appearance of the first annular (A1) pulley–flexor tendon complex in patients with trigger fingers. Methods. Thirty‐three trigger fingers in 33 patients were examined with a 7‐ to 15‐MHz probe. A control group consisted of 20 patients without trigger fingers. The study included systematic measurement of the thickness of the A1 pulley and a power Doppler assessment of the pulleys, tendons, and tendon sheaths. Results. Thickening and hypoechogenicity of the A1 pulley were found in all patients with trigger fingers. Measurements of A1 pulley thickness were significantly different (P < .0001) between the groups without trigger fingers (mean, 0.5 mm; range, 0.4–0.6 mm) and with trigger fingers (mean, 1.8 mm; range, 1.1–2.9 mm). Hypervascularization of the A1 pulley on power Doppler imaging was found in 91% of the trigger fingers but was never found in the healthy control group. Flexor tendinosis was found in 48% of the trigger fingers; tenosynovitis was found in 55%; and both were found in 39%. In the control group, tenosynovitis and tendinosis were not found. Conclusions. Thickening and hyper‐vascularization of the A1 pulley are the hallmarks of trigger fingers on sonography. Other frequently observed features include distal flexor tendinosis and tenosynovitis.

MRI Assessment of Recurrent Carpal Tunnel Syndrome After Open Surgical Release of the Median Nerve

OBJECTIVE The purpose of this study was to retrospectively determine the accuracy of MRI in identification of the morphologic features of median nerve dysfunction after surgical release of the median nerve for carpal tunnel syndrome. MATERIALS AND METHODS Two blinded readers independently evaluated axial 1.5-T MR images for retinacular regrowth, morphologic characteristics of the median nerve, and presence of mass effect, fibrosis, and carpal tunnel decompression. All 47 patients (11 men, 36 women; mean age, 55 years; range, 27-81 years) had undergone open surgical release of the median nerve for carpal tunnel syndrome. Thirty-five patients had electromyographic evidence of recurrent carpal tunnel syndrome. The other 12 patients did not have electrophysiologic evidence of recurrent carpal tunnel syndrome and were the control group. RESULTS A statistically significant difference between the recurrent carpal tunnel syndrome and control groups was found for fibrosis (p = 0.009), nerve enhancement (p = 0.04), and median nerve width (p = 0.008) and ratio (p = 0.01) at the pisiform level. CONCLUSION MRI may be used in association with electromyography for accurate postoperative evaluation of the carpal tunnel.

Is Superolateral Hoffa Fat Pad Edema a Consequence of Impingement between Lateral Femoral Condyle and Patellar Ligament

PURPOSE To evaluate whether knee extensor mechanism features are associated with superolateral Hoffa fat pad edema at magnetic resonance imaging. MATERIALS AND METHODS Institutional review board approval and written consent from all patients were obtained. Patients with superolateral Hoffa fat pad edema (n = 30) and a control group without edema of the fat pad (n = 60) were evaluated prospectively with magnetic resonance (MR) imaging. Demographic data and extensor mechanism features were compared, including trochlear depth, lateral trochlear inclination, patellar tilt angle, patellar height ratio, distance between patellar ligament and lateral trochlear facet, distance from the tibial tubercle to the trochlear groove, patellar facet asymmetry, and patellar ligament abnormalities. RESULTS The following variables were associated with superolateral Hoffa fat pad edema in the multivariable models: patellar height ratio (P = .023), shortest distance between patellar ligament and lateral trochlear facet (P < .001), and distance from the tibial tubercle to the trochlear groove (P = .046). Of all demographic and degenerative variables, only age was significantly associated, with younger patients more likely to have superolateral Hoffa fat pad edema (P < .009). CONCLUSION A high-riding patella, a short distance between the patellar ligament and the lateral trochlear facet, and an increased distance from the tibial tubercle to the trochlear groove are associated with superolateral Hoffa fat pad edema at MR imaging. These results are suggestive of impingement between the lateral femoral condyle and the posterior aspect of the patellar ligament in these patients.

Inflammation and cancer, the mastocytoma P815 tumor model revisited: Triggering of macrophage activation in vivo with pro-tumorigenic consequences

Subcutaneous in vivo injections of cells of the mastocytoma line P815 in syngenic DBA/2 mice induce locally fast growing solid tumors. These have been used extensively as a cancer model to analyze and manipulate the relationship between tumor cells and hosts immune defenses. We report that progression of P815 tumors in vivo was accompanied by a burst (Days 5–7) of local inflammatory cells recruitment and angiogenesis observed histologically, corroborated in vivo by MRI with gadolinium, overtranscription of macrophage activation marker genes, secretion of TNF‐α by regional lymph node cells and concomitant systemic inflammation. No substantial overtranscriptions of either VEGF or IL‐10 or TGF‐β genes were observed. Induction of COX‐2 gene was a late event. To establish a possible relationship between the tumor‐induced local, regional and systemic increase of pro‐inflammatory mediators and progression of tumors in vivo, we carried out experiments deliberately modulating the inflammatory status of the recipient animals. Pretreatment of recipient animals by i.p. injection of thioglycolate accelerated P815 tumor growth. At the opposite, treatment of mice with either a COX‐1 + COX‐2 inhibitor (aspirin, 1 mg/day/mouse) or a specific COX‐2 inhibitor (celecoxib, 0.13 mg/day/mouse) for 2 weeks after injection of tumor cells, significantly reduced the size and growth rate of tumors compared to control mice. Experiments carried out in vitro indicated that peritoneal macrophages from untreated animals were strongly activated by live P815 cells and by P815 membrane preparations. The tumor‐induced inflammatory reaction could establish a local micro environment favoring tumor progression. The P815 tumor model might be helpful to recognize important factors controlling host/tumor relationship.

Hand and wrist involvement in systemic sclerosis: US features.

PURPOSE To characterize ultrasonographic (US) features in the hand of patients with systemic sclerosis (SSc) and to evaluate the sensitivity of US in the detection of calcinosis and acroosteolysis. MATERIALS AND METHODS The local ethics committee approved this study, and oral informed consent was obtained. A total of 44 consecutive patients with SSc (34 women; mean age, 56.1 years ± 12.1 [standard deviation]; 10 men; mean age, 45.0 years ± 14.0) and 30 healthy control subjects (20 women; mean age, 46.3 years ± 12.1; 10 men; mean age, 39.6 years ± 10.8) were included between October 2010 and December 2011. Bilateral US, including Doppler assessment of the wrists, hands, and fingers, was performed, and presence of synovitis, tenosynovitis with or without a layered appearance, calcifications, acroosteolysis, and distal vascularization was recorded. Radiography of both hands was performed to assess for acroosteolysis and calcinosis. Frequency of US features, sensitivity of US for calcinosis and acroosteolysis, and respective confidence intervals were calculated. RESULTS Synovitis was found in 17 patients (39%). Tenosynovitis was found in 12 patients (27%), and it had a layered pattern in 15 (41%) of 37 cases. Calcinosis was found in 17 patients (39%) with US, with a sensitivity of 89%. Acroosteolysis was found in nine (20%) patients with US and in 10 (23%) patients with radiography, with 90% sensitivity for US. Distal vascularization was detected in 26 patients (59%) and 30 control subjects (100%) and was in contact with the acroosteolysis bed in seven (78%) of nine patients with SSc. CONCLUSION US can be used to assess features of SSc, including synovitis, tenosynovitis, calcinosis, acroosteolysis, and distal vascularization and is sensitive for calcinosis and acroosteolysis detection. A layered pattern (similar to the appearance of an artichoke heart) of tenosynovitis was seen commonly. Online supplemental material is available for this article.

Fractures of the ankylosed spine: MDCT and MRI with emphasis on individual anatomic spinal structures.

OBJECTIVE The purpose of this article is to illustrate the spectrum of MDCT and MRI appearances of spinal fractures in ankylosing spondylitis and diffuse idiopathic skeletal hyperostosis. CONCLUSION Spinal fractures associated with ankylosing spondylitis and diffuse idiopathic skeletal hyperostosis usually involve the three columns of the spine, and injury to the posterior osteoligamentous component is the hallmark of these fractures. Osseous and ligamentous injuries can be accurately visualized and analyzed with MDCT with multiplanar reformation and with MRI.

Study of the joint space of the hip on supine and weight-bearing digital radiographs

AIM To compare hip joint space on supine and weight-bearing anteroposterior digital radiographs. MATERIALS AND METHODS Fifty anteroposterior views of the hip in 25 patients were taken in supine and weight-bearing positions on a fluoroscopic unit. Two observers in a double-blind study assessed the width of the joint space on an Easy Vision unit with an indirect method of measurement (metric index). RESULTS Inter-observer and intra-observer variabilities of the metric index were less than 4.1%. There was no significant difference of the metric index of the hip (P>0.05), between supine and weight-bearing positions. CONCLUSION There is no significant difference of the width of the joint space of the hip between supine and weight-bearing anteroposterior radiographs. Measuring joint space loss in osteoarthritis of the hip with anteroposterior views should be done with radiographs of the hip in the supine position to improve image quality.

Direct Arthrography of the Pisotriquetral Joint

OBJECTIVE The purpose of this study was to describe and evaluate a simple and safe procedure for direct arthrography of and steroid injection into the pisotriquetral joint. CONCLUSION Direct pisotriquetral arthrography using a medial approach is an effective and easy-to-perform technique for injection of steroids.