Intercostal Nerve Block Using an Innovative Intraneedle Ultrasound Transducer: A Proof-of-Concept study.

Intercostal nerve block is a widely used and effective approach to providing regional anesthesia in the thoracic region for pain relief. However, during ultrasound-guided intercostal nerve block, inaccurate identification of the anatomic structures or suboptimal positioning of the needle tip may result in complications and blockade failure. In this study, we designed an intraneedle ultrasound (INUS) system and validated its efficacy in identifying anatomic structures relevant to thoracic region anesthesia. The 20-MHz INUS transducer comprised a single lead magnesium niobate-lead titanate crystal, and gain was set to 20 dB. It fit into a regular 18G needle and emitted radiofrequency-mode ultrasound signals at 1 mm from the needle tip. One hundred intercostal punctures were performed in 10 piglets. Intercostal spaces were identified by surface ultrasound or palpation and located by inserting and advancing the INUS transducer needle until the appropriate anatomy was identified. Blockade success was defined by ideal saline and dye spreading and confirmed by dissection. The pleura had a distinctive ultrasound signal, and successful detection of the intercostal muscles, endothoracic fascia and double-layered parietal and visceral pleura was achieved in all 100 puncture attempts. INUS allows real-time identification of intercostal structures and facilitates successful intercostal nerve blocks.

Single-scan rest/stress imaging with 99mTc-Sestamibi and cadmium zinc telluride-based SPECT for hyperemic flow quantification: A feasibility study evaluated with cardiac magnetic resonance imaging.

INTRODUCTION: We aimed to evaluate whether the hyperemic myocardial blood flow (MBF) can be estimated using cadmium zinc telluride (CZT)-based single-photon emission computed tomography (SPECT) cameras with a single, rapid rest/stress dynamic scan. Dynamic contrast-enhanced (DCE) cardiac magnetic resonance imaging (MRI) was used as a reference modality for flow measurement. MATERIALS AND METHODS: The proposed protocol included both the rest and stress acquisitions within a 24-min scan. Patients were first injected with 99mTc-Sestamibi at the resting state. Sixty minutes after the first injection, the subject was positioned via scintigraphy, after which the list-mode data acquisition was initiated and continued for 24 minutes. Five minutes after data acquisition was initiated, a stressed state was induced via dipyridamole infusion, after which a second dose of 99mTc-Sestamibi was injected. Dynamic SPECT images were reconstructed for all subjects, who also underwent T1-weighted cardiac DCE-MRI performed on days other than those of the SPECT studies. MBF values were estimated for the rest and stress MRI studies, and for the stress portion of the SPECT study. The SPECT-measured hyperemic MBF was compared with the MR-measured hyperemic MBF and coronary flow reserve (CFR), based on the regions of interest. RESULTS: A total of 30 subjects were included in this study. The hyperemic MBF estimated from SPECT showed a strong correlation with the MR-measured hyperemic MBF (r2 = 0.76) and a modest correlation with the MR-measured CFR (r2 = 0.56). Using MR-measured CFR <1.3 as a cutoff for coronary stenosis, we found that the SPECT-measured hyperemic MBF served as a useful clinical index with 94% sensitivity, 90% specificity, and 93% accuracy. CONCLUSIONS: Hyperemic MBF can be measured with a rapid, single-scan rest/stress study with CZT-based SPECT cameras.