US guidance of interventional procedures

Advances in ultrasound (US) machine and transducer design have improved the ability of US to guide interventional procedures. Though affording excellent guidance without radiation and at relatively low cost, US remains underutilized because of lack of understanding and experience in this technique. This article illustrates the role that US has in interventional radiology and explains how to place a needle in a target under US guidance.     

Multiple-image in-room CT imaging guidance for interventional procedures

This HIPAA-compliant study was approved by the institutional review board; informed consent was not required. The purpose of this study was to retrospectively compare room use time for interventional procedures performed with multiple-image multi-detector row computed tomographic (CT) fluoroscopy (n=196) and single-image spiral CT fluoroscopy (n=175). There was no statistically significant difference in age, sex, or procedural type between the two groups. The median room use time was 90 minutes (interquartile range, 65-120 minutes) for the single-image technique and 75 minutes (interquartile range, 60-105 minutes) for the multiple-image technique. A two-sample t test with equal variance assumption on the log-transformed data showed a statistically significant difference in log time (P<.001) between the two groups. This time savings could potentially have a substantial clinical effect on resource use and patient throughput.     

Percutaneous abdominal and pelvic interventional procedures using CT fluoroscopy guidance.

OBJECTIVE: The purpose of our study was to assess the use of low-milliamperage CT fluoroscopy guidance for percutaneous abdominopelvic biopsy and therapeutic procedures. MATERIALS AND METHODS: We reviewed the clinical records and relevant imaging studies of 97 patients who underwent 119 percutaneous CT fluoroscopy-guided abdominal or pelvic procedures: fluid collection aspiration or drainage catheter insertion (n = 59), biopsy (n = 49), hepatocellular carcinoma ethanol ablation (n = 6), chemoneurolysis (n = 4), and brachytherapy catheter insertion (n = 1). These procedures were guided using a helical CT scanner providing real-time fluoroscopy reconstruction at six frames per second. A control panel and video monitor beside the gantry allowed direct operator control during all interventional procedures. RESULTS: One hundred twelve (94.1%) procedures were successfully performed using either a stand-off needle holder and continuous real-time CT fluoroscopy guidance or incremental manual insertion and intermittent CT fluoroscopy to confirm position. Image quality using low milliamperage was adequate for needle or drainage tube placement in all but two low-contrast liver lesions. Two hematomas were accessed but yielded no fluid on aspiration; one drainage procedure was abandoned after the patient developed endotoxic shock. Imaging of ethanol distribution during injection facilitated tumor ablation and neurolytic procedures. CT fluoroscopy allowed rapid assessment of needle, guidewire, dilator, and catheter placement, especially in nonaxial planes. Average CT fluoroscopy time for biopsy and therapeutic procedures was 133 sec (range, 35-336 sec) and 186 sec (range, 20-660 sec), respectively. CONCLUSION: CT fluoroscopy is a practical clinical tool that facilitates effective performance of percutaneous abdominal and pelvic interventional procedures.     

Abdominal cystic lymphangiomas: US and CT findings

We retrospectively analyzed six cases of abdominal cystic lymphangiomas (CL), who had undergone surgical resection. These cases had been evaluated by several modalities: ultrasonography (US), computed tomography (CT), angiography and fine needle aspiration. No age predilection was found. All patients were symptomatic. The most common presenting symptoms were abdominal pain (66%), palpable mass (66%), fever (50%) and vomiting (30%). US showed septations (85%) and unicameral mass (15%); in three cases (50%) echogenic material within the cyst was found, probably due to hemorrhage and infection. CT showed capsular enhancement in all cases. Capsular and septation thickness were slightly increased in cases of infection or bleeding. At CT the contents were usually of fluid attenuation (66%); in 33% the attenuation values were higher, probably because of internal bleeding and infection. US was superior to CT in the demonstration of septations and the internal nature of the cysts. The major role of imaging is to demonstrate the cystic nature of these abdominal masses, because they do not have specific signs or symptoms that could allow a clinical diagnosis.     

Abdominal vascular emergencies: US and CT assessment

Acute vascular emergencies can arise from direct traumatic injury to the vessel or be spontaneous (non-traumatic).The vascular injuries can also be divided into two categories: arteial injury and venous injury.Most of them are life-treatening emergencies, sice they may cause an important ipovolemic shock or severe ischemia in their end organ and require prompt diagnosis and treatment.In the different clinical scenarios, the correct diagnostic approach to vascular injuries isn’t firmly established and advantages of one imaging technique over the other are not obvious.Ultrasound (US) is an easy accessible, safe and non-invasive diagnostic modality but Computed Tomography (CT) with multiphasic imaging study is an accurate modality to evaluate the abdominal vascular injuries therefore can be considered the primary imaging modality in vascular emergencies.The aim of this review article is to illustrate the different imaging options for the diagnosis of abdominal vascular emergencies, including traumatic and non traumatic vessel injuries, focusing of US and CT modalities.     

CT fluoroscopy for thoracic interventional procedures

In the past several years, CT fluoroscopy has proved a valuable new technique in guiding the performance of intrathoracic procedures. Several approaches to using CT fluoroscopy are discussed. We have found an interrupted, real-time technique optimal to facilitate biopsy of percutaneous lung nodules, particularly small lesions. The technique is also valuable in assisting thoracic drainage procedures. This article also discusses the use of CT fluoroscopy to guide transbronchial needle aspiration, which is another potentially important application.     

CT引导下肝脓肿穿刺置管引流术的探讨

目的 探讨CT引导下肝脓肿穿刺引流术的方法和疗效.方法 本组20例肝脓肿患者,均经临床、生化和影像学(CT)检查确诊为肝脓肿,行CT引导下定位穿刺抽吸并置管引流.脓肿位于肝左叶6例,肝右叶9例,肝2叶5例.结果 14例为单个脓肿,6例为多发脓肿,单个脓肿经1次抽吸后脓肿完全消失9例,1例经2次抽吸基本消失,多发或多房脓肿穿刺先抽较大脓肿,后抽较小脓肿,或分次抽吸,20例均放置引流管并冲洗,平均引流置管时间为19.2 d,所有患者至随访截止日未见复发.结论 CT引导下穿刺抽吸引流足治疗肝脓肿的非常有效的方法.     

Potentials of laser guidance system for percutaneous musculoskeletal procedures

 Early experience using a new laser guidance device to assist CT-guided percutaneous musculoskeletal procedures is presented. We describe six cases which demonstrate typical musculoskeletal applications of laser guidance. In our experience laser guidance for these procedures resulted in improved accuracy with no significant increase in biopsy time when a short learning period is considered. Other musculoskeletal procedures may benefit from laser guidance compared with current standard CT-guided techniques, particularly when precision and accuracy are essential.     

Radiation exposure of the interventional radiologist during percutaneous biopsy using a multiaxis interventional C-arm CT system with 3D laser guidance: a phantom study

Objective:

Evaluation of absolute radiation exposure values for interventional radiologists (IRs) using a multiaxis interventional flat-panel C-arm cone beam CT (CBCT) system with three-dimensional laser guidance for biopsy in a triple-modality, abdominal phantom.

Methods:

In the phantom, eight lesions were punctured in two different angles (in- and out-of-plane) using CBCT. One C-arm CT scan was performed to plan the intervention and one for post-procedural evaluation. Thermoluminescent dosemeters (TLDs) were used for dose measurement at the level of the eye lens, umbilicus and ankles on a pole representing the IRs. All measurements were performed without any lead protection. In addition, the dose–area product (DAP) and air kerma at the skin entrance point was documented.

Results:

Mean radiation values of all TLDs were 190 µSv for CBCT (eye lens: 180 µS, umbilicus: 230 µSv, ankle: 150 µSv) without a significant difference (p > 0.005) between in- and out-of-plane biopsies. In terms of radiation exposure of the phantom, the mean DAP was not statistically significantly different (p > 0.05) for in- and out-of-plane biopsies. Fluoroscopy showed a mean DAP of 7 or 6 μGym², respectively. C-arm CT showed a mean DAP of 5150 or 5130 μGym², respectively.

Conclusion:

In our setting, the radiation dose to the IR was distinctly high using CBCT. For dose reduction, it is advisable to pay attention to lead shielding, to increase the distance to the X-ray source and to leave the intervention suite for C-arm CT scans.

Advances in knowledge:

The results indicate that using modern navigation tools and CBCT can be accompanied with a relative high radiation dose for the IRs since detector angulation can make the use of proper lead shielding difficult.     

Patient and personnel exposure during CT fluoroscopy-guided interventional procedures

PURPOSE: To estimate patient dose and personnel exposure from phantom measurements during computed tomographic (CT) fluoroscopy, to use the estimates to provide users with dose information, and to recommend methods to reduce exposure. MATERIALS AND METHODS: Surface dose was estimated on a CT dosimetric phantom by using thermoluminescent dosimetric (TLD) and CT pencil chamber measurements. Scatter exposure was estimated from scattered radiation measured at distances of 10 cm to 1 m from the phantom. Scatter exposures measured with and without placement of a lead drape on the phantom surface adjacent to the scanning plane were compared. RESULTS: Phantom surface dose rates ranged from 2.3 to 10. 4 mGy/sec. Scattered exposure rates for a commonly used CT fluoroscopic technique (120 kVp, 50 mA, 10-mm section thickness) were 27 and 1.2 microGy/sec at 10 cm and 1 m, respectively, from the phantom. Lead drapes reduced the scattered exposure by approximately 71% and 14% at distances of 10 and 60 cm from the scanning plane, respectively. CONCLUSION: High exposures to patients and personnel may occur during CT fluoroscopy-guided interventions. Radiation exposure to patients and personnel may be reduced by modifying CT scanning techniques and by limiting fluoroscopic time. In addition, scatter exposure to personnel may be substantially reduced by placing a lead drape adjacent to the scanning plane.     

Technique for providing analgesia during percutaneous biliary interventional procedures

AIMS: To evaluate the efficacy of interpleural analgesia during percutaneous transhepatic biliary procedures. METHOD: With the patient lying in the left lateral decubitus position a right sided interpleural catheter was sited at a chosen point between the 6th and 9th interspaces. Lignocaine was injected to provide a splanchnic and intercostal nerve block. The technique of interpleural block (IPB) is described. Assessment of the pulse, BP and O(2)saturation during the subsequent biliary procedure was made. The patient evaluated the maximum degree of pain felt during the biliary procedure according to a four-point pain scale (0-3). The nurse and radiologist also gave an objective assessment of the pain score. RESULTS: An IP catheter was successfully placed in 22 patients, one patient having the IPB on two occasions. Siting of the IP catheter failed in three patients. Good analgesia with no requirement for further analgesia or sedation was achieved in 11 patients on 12 occasions. Seven patients required additional small doses of analgesia for mild pain during the biliary procedure. IPB failed in four patients who required additional analgesia and sedation. No complication of the IPB technique occurred in our patient group. CONCLUSION: IPB is a safe and relatively effective method for analgesia during transhepatic percutaneous biliary procedures.     

职业辐射剂量:血液透析动静脉瘘和移植物的经皮介入手术治疗

摘要目的评估在经皮介入手术治疗血液透析动静脉瘘(AVF)和动静脉移植物(AVG)过程中术者所接受的辐射剂量。材料与方法57例病人行77次手术,手术过程中介入放射医师戴2个戒指状放射计量表、双腿戴2个热释光计量仪,前额戴1个热释光计量仪。记录剂量-面积值、透视时间、总的手术时间以及眼晶状体、手、腿的辐射剂量。不同病人手术方式、手术入路的位置和成像设备也不相同。使用符号秩和、等级秩和方法进行统计学分析。     

Benefits and safety of CT fluoroscopy in interventional radiologic procedures

PURPOSE: To determine the benefits and safety of computed tomographic (CT) fluoroscopy when compared with conventional CT for the guidance of interventional radiologic procedures. MATERIALS AND METHODS: Data on 203 consecutive percutaneous interventional procedures performed with use of CT fluoroscopic guidance and 99 consecutive procedures with conventional CT guidance were obtained from a questionnaire completed by the radiologists and CT technologists who performed the procedures. The questionnaire specifically addressed radiation dose measurements to patients and personnel, total procedure time, total CT fluoroscopy time, mode of CT fluoroscopic guidance (continuous versus intermittent), success of procedure, major complications, type of procedure (biopsy, aspiration, or drainage), site of procedure, and level of operator experience. RESULTS: The median calculated patient absorbed dose per procedure and the median procedure time with CT fluoroscopy were 94% less and 32% less, respectively, than those measurements with conventional CT scanning (P <.05). An intermittent mode of image acquisition was used in 97% of the 203 cases. This resulted in personnel radiation dosimetric readings below measurable levels in all cases. CONCLUSION: As implemented at the authors' institution, use of CT fluoroscopy for the guidance of interventional radiologic procedures markedly decreased patient radiation dose and total procedure time compared with use of conventional CT guidance.     

CT fluoroscopy--guided interventional procedures: techniques and radiation dose to radiologists.

PURPOSE: To determine the radiation dose to radiologists who perform computed tomographic (CT) fluoroscopic interventional procedures by using a quick-check method and a low-milliampere technique. MATERIALS AND METHODS: Two hundred twenty CT fluoroscopy--guided interventional procedures were performed in 189 patients. Procedures included 57 spinal injections, 17 spinal biopsies, 24 chest biopsies, 20 abdominal aspirations, 44 abdominal biopsies, and 58 abdominal drainages. Procedure details were prospectively recorded and included site, depth, target diameter, milliampere value, kilovolt peak, fluoroscopic time, and CT technique (continuous CT fluoroscopy, quick-check method, or a combination of these techniques). An individual collar and finger radiation detector were worn by each radiologist during each procedure to determine the dose per procedure. RESULTS: The quick-check technique was performed in 191 (87%) of 220 procedures. Four procedures were performed with continuous CT fluoroscopy, and a combination technique was used for 25 (11%) procedures. The overall mean CT fluoroscopic time was 17.9 seconds (range, 1.2--101.5 seconds). The mean milliampere value was 13.2 mA (range, 10--50 mA). The overall mean radiologist radiation dose per procedure was 2.5 mrem (0.025 mSv) (whole body). Individual procedure doses ranged from 0.66 to 4.75 mrem (0.007--0.048 mSv). The finger radiation dose was negligible. CONCLUSION: By using a low-milliampere technique and the quick-check method, CT fluoroscopic time and radiation exposure can be minimized.