Prospective 1-year follow-up pilot study of CT-guided microwave ablation in the treatment of bone and soft-tissue malignant tumours.

PURPOSE: The aims of this work were to assess the feasibility, efficacy, short-term outcome and safety of microwave ablation (MWA) in the treatment of malignant musculoskeletal tumours. MATERIALS AND METHODS: Sixteen bone and soft-tissue malignant tumours were prospectively included and were treated by CT-guided MWA. The percentage and size of necrosis of the lesions were measured by contrast-enhanced MRI before the procedure and after 1, 3, 6 and 12 months. mRECIST criteria were used to assess tumour response. Procedural success was defined as ≥80 % necrosis. Patient pain (as assessed using a numeric visual scale (NVS)) and side effects were noted. RESULTS: Six osteolytic metastases, five osteoblastic metastases and five soft tissue sarcomas were treated. At 1 month, 40 % were treated completely, the percentage of necrosis was 85 ± 30.4 %, and the success rate was 80 %. At 3, 6 and 12 months the success rate was 80 %, 76.9 % and 63.6 %, respectively. At 12 months, four lesions (36.3 %) still had no recurrence. Mean NVS during the procedure was 3.5 ± 2.8. One patient had transitory sciatica without neurological deficit that was treated medically. CONCLUSION: CT-guided MWA of bone and soft-tissue malignant tumours is efficient, well tolerated and has good short-term anti-cancer effects. KEY POINTS: • CT-guided MWA is efficient in treating musculoskeletal malignant tumours. • This prospective pilot study showed MWA induces high percentages of tumour necrosis. • MWA has good short-term anti-cancer effects. • MWA has healing potential when lesions can be completely necrosed. • CT-guided MWA under equimolar mixture of oxygen-nitrous oxide inhalation is well tolerated.

Prospective pilot study of CT-guided microwave ablation in the treatment of osteoid osteomas.

PURPOSE: The aims of this work were to assess the feasibility and efficacy of CT-guided microwave ablation (MWA) in the treatment of osteoid osteomas (OOs). MATERIALS AND METHODS: Thirteen consecutive patients (range 11-31 years old) presenting with OO were prospectively included and treated by CT-guided MWA. Power and duration of MWA were both recorded. The patient's pain was assessed using a numeric pain rating scale (NRS), and side effects were recorded during procedures, after 1 day, 7 days and 1 month. The nidus vascularization and the volume of necrosis induced by MWA were assessed using contrast-enhanced MRI. Success was defined as the complete relief of the patient's pain 1 month after the first procedure, associated with necrosis of the nidus on follow-up MRI. RESULTS: The success rate was up to 92.3% (12/13). At 1 day, 7 days and 1 month, the median NRSs were respectively 5 [interquartile range (IQR) 2-5], 0 (IQR 0-1) and 0 (IQR 0-0). Side effects observed were one partial and self-resolving lesion of a sensory branch of the radial nerve and two skin burns. The median power of the MWA used was 60 W (IQR 50-60) with a 1.5-min duration (IQR 1-2), leading to MWA-induced necrosis measuring on average 23 × 15 × 16 mm. CONCLUSION: CT-guided MWA of OO has a success rate that appears to be almost similar to that of laser or radiofrequency ablation, but care must be taken to prevent nerve or skin lesions.

Evaluation of the Effect of an Anisotropic Medium on Shear Wave Velocities of Intra-Muscular Gelatinous Inclusions.

In highly anisotropic biological tissues such as muscle or tendons, calculating Young's modulus from the shear wave speed (csw) by using shear wave elastography (SWE) involves a complex transversally isotropic rheological model not yet used in common practice. To our knowledge, the effect of muscle anisotropy on csw of intra-muscular lesions has not yet been investigated. The objective of our study was to define the effect of an anisotropic medium on csw of intra-muscular gelatinous inclusions. We conducted a prospective monocentric, in vitro study in order to examine the quantitative and qualitative SWE behavior of a 9-mm gelatinous intra-muscular implant depending on the orientation of the probe relative to the muscle fibers. There were very significant differences in the prevalence of SWE signal void (p < 0.01) and in the csw (p < 0.01) in the gelatinous intra-muscular implants depending on the orientation of the probe relative to the fibers. Performing the csw measurements of centimetric intra-muscular lesions by orienting the probe perpendicular to the fibers decreases the probability of artifacts occurring at high intensity interfaces.

Multi-modal imaging of the subscapularis muscle.

The subscapularis (SSC) muscle is the most powerful of the rotator cuff muscles, and plays an important role in shoulder motion and stabilization. SSC tendon tear is quite uncommon, compared to the supraspinatus (SSP) tendon, and, most of the time, part of a large rupture of the rotator cuff. Various complementary imaging techniques can be used to obtain an accurate diagnosis of SSC tendon lesions, as well as their extension and muscular impact. Pre-operative diagnosis by imaging is a key issue, since a lesion of the SSC tendon impacts on treatment, surgical approach, and post-operative functional prognosis of rotator cuff injuries. Radiologists should be aware of the SSC anatomy, variability in radiological presentation of muscle or tendon injury, and particular mechanisms that may lead to a SSC injury, such as coracoid impingement. TEACHING POINTS: • Isolated subscapularis (SSC) tendon tears are uncommon. • Classically, partial thickness SSC tendon tears start superomedially and progress inferolaterally. • Long head of biceps tendon medial dislocation can indirectly signify SSC tendon tears. • SSC tendon injury is associated with anterior shoulder instability. • Dynamic ultrasound study of the SSC helps to diagnose coracoid impingement.

Viscoelasticity in Achilles tendonopathy: quantitative assessment by using real-time shear-wave elastography.

PURPOSE: To investigate the differences in viscoelastic properties between normal and pathologic Achilles tendons (ATs) by using real-time shear-wave elastography (SWE). MATERIALS AND METHODS: The institutional review board approved this study, and written informed consent was obtained from 25 symptomatic patients and 80 volunteers. One hundred eighty ultrasonographic (US) and SWE studies of ATs without tendonopathy and 30 studies of the middle portion of the AT in patients with tendonopathy were assessed prospectively. Each study included data sets acquired at B-mode US (tendon morphology and cross-sectional area) and SWE (axial and sagittal mean velocity and relative anisotropic coefficient) for two passively mobilized ankle positions. The presence of AT tears at B-mode US and signal-void areas at SWE were noted. RESULTS: Significantly lower mean velocity was shown in tendons with tendonopathy than in normal tendons in the relaxed position at axial SWE (P < .001) and in the stretched position at sagittal (P < .001) and axial (P = .0026) SWE. Tendon softening was a sign of tendonopathy in relaxed ATs when the mean velocity was less than or equal to 4.06 m · sec(-1) at axial SWE (sensitivity, 54.2%; 95% confidence interval [CI]: 32.8, 74.4; specificity, 91.5%; 95% CI: 86.3, 95.1) and less than or equal to 5.70 m · sec(-1) at sagittal SWE (sensitivity, 41.7%; 95% CI: 22.1, 63.3; specificity, 81.8%; 95% CI: 75.3, 87.2) and in stretched ATs, when the mean velocity was less than or equal to 4.86 m · sec(-1) at axial SWE (sensitivity, 66.7%; 95% CI: 44.7, 84.3; specificity, 75.6%; 95% CI: 68.5, 81.7) and less than or equal to 14.58 m · sec(-1) at sagittal SWE (sensitivity, 58.3%; 95% CI: 36.7, 77.9; specificity, 83.5%; 95% CI: 77.2, 88.7). Anisotropic results were not significantly different between normal and pathologic ATs. Six of six (100%) partial-thickness tears appeared as signal-void areas at SWE. CONCLUSION: Whether the AT was relaxed or stretched, SWE helped to confirm and quantify pathologic tendon softening in patients with tendonopathy in the midportion of the AT and did not reveal modifications of viscoelastic anisotropy in the tendon. Tendon softening assessed by using SWE appeared to be highly specific, but sensitivity was relatively low.