CT guidance

The author has used percutaneous CT guided thrombin injection in six patients where pancreatitis associated aneurysms could not be seen at selective angiography. The technique is relatively simple, the aneurysm being punctured with a 21-Gauge saline flushed needle under CT guidance... 

Using CT guidance the initial needle tip placement will be into the leak sac (Fig. 14.3). However, with fluoroscopic guidance and a relatively small leak, the initial puncture may end up in thrombus. In these cases, the leak sac can usually be found fairly easily using a hydrophilic guidewire and catheter. 

In conclusion, real-time registration and fusion of pre-procedure CT volume images with intra-procedure US are feasible and accurate in the experimental setting. Further studies are warranted to validate the system under clinical conditions. For simple biopsies, an experienced interventional radiologist will not ask for such a guidance tool and, given the cost and availability, US and CT guidance... 

Sheafor DH, Paulson EK, Kliewer MA et al (2000) Comparison of sonographic and CT guidance techniques. Does CT fluoroscopy decrease procedure time AJR 174 939-942... 

Fichtinger G, DeWeese TL, Patriciu A et al (2002) System for robotically assisted prostate biopsy and therapy with intraoperative CT guidance. Acad Radiol 9 60-74 Geis WP, Kim HC, Brennan EJ Jr, McAfee PC, Wang Y (1996) Robotic arm enhancement to accommodate improved efficiency and decreased resource utilization in complex minimally invasive surgical procedures. Stud Health Technol Inform 29 471-481... 

The nerve trajectory is locaUzed under CT guidance. An intravenous contrast medium is routinely used... 

Fig. 11.1. Pancoast s syndrome with major cervical spine invasion in a patient with excruciating pain in the upper limb. A 22-gauge needle was introduced just lateral to the transverse process of the affected vertebra under CT guidance. The spinal nerve lies in the sulcus of the transverse process. Brachial plexus block was performed at C5 and C6 level. Slight weakness of the limb after alcoholization. Good pain relief was obtained lasting until death of the patient 6 weeks later...

The thoracic sympathetic ganglia are located in front of the head of the ribs and the pleura is immediately in front of and closely related to the ganglia. Under CT guidance, a 22-gauge needle is inserted percu-taneously along the lateral aspect of the vertebral body at the level of, or superior to, the tumoral lesion. The tip of the needle is located between the vertebral periosteum and the parietal pleura, in front of the head of the rib. After injection of 3 ml of 1% lidocaine diluted with contrast media, 3-5 ml... 

The patient is placed in a prone position. After intravenous bolus injection of contrast medium, the celiac and superior mesenteric arteries are localized. The 22-gauge needle is positioned under precise CT guidance near the celiac artery. A transaortic approach pathway could be used. After CT confirmation of needle tip position, the procedure described previously is performed. A bilateral block is often necessary with the posterior approach technique (Kurdziel and Dondelinger 1990 Schild 1998 Lieberman and Waldman 1990 Whiteman et al. 1986) (Fig. 11.7c). 

Under CT guidance, a 22-gauge needle is inserted into the retrocrural space at the level of T11-T12 by a posterior percutaneous approach. The needle tip is located just lateral to the anterolateral surface of the vertebra where the three thoracic splanchnic nerves are located in close proximity to one another (Fig. 11.8). After injection of 2 ml of bupivacaine diluted with contrast medium confirming the location of the needle tip, 10 ml of ethanol (96%) are injected on both sides. A bilateral block is often essential for relief of upper abdominal pain (Bonica 1990b Kurdziel and Dondelinger 1990). 

In splanchnic nerve block, complications like orthostatic arterial hypotension are unusual because the procedure is less likely to involve the lumbar sympathetic chain than with celiac plexus block. Pneumothorax, intrathecal, and intravascular injection can be avoided under precise CT guidance (Kurdziel and Dondelinger 1990). 

Gangi A et al (1994a) Injection of alcohol into bone metat-stases under CT guidance. J Comput Assist Tomogr 18 932-935... 

Montero Matamala A et al (1988) The percutaneous anterior approach to the celiac plexus using CT guidance. Pain 34 285-288... 

Sequential CT guidance. For planning of the access route, a CT scan of the region of interest is performed first. The preliminary scan can be performed without contrast, if a recent diagnostic study is available and the lesion is easily visible. In the chest, a nonenhanced CT scan (S3-mm slice thickness) is also sufficient for detection of intrapulmonary lesions suitable for aspira-... 

Pancreas. Typically, the pancreas is surrounded by various organs like the stomach, liver, transverse colon, kidney, or major vessels. In particular, needle biopsy of small suspect masses in the pancreatic head is therefore usually regarded as technically sophisticated, and CT guidance preferred instead of ultrasound (Fig. 37.5). For differentiation of the tumor from surrounding normal parenchyma or inflammation, a contrast-enhanced CT scan obtained in an arterial phase should generally be performed prior to the intervention. The most common access route is from an anterior approach and often... 

Retroperitoneum. Biopsies of retroperitoneal lesions are usually performed under CT guidance. With the most common posterior approach, the needle passes through or parallel to the psoas muscle (Fig. 37.6). Small-gauge needles are only necessary using an anterior approach. 

FNAB in the abdomen with both US and CT guidance has been described as safe and technically successful procedure by several authors (Ferrucci et al. 1980 Memel et al. 1996 Smith 1991 Welch et al. 1989). CT-guided FNAB of liver lesions has been reported to have sensitivity rates of 92% and specificity rates of 96% (Tuning et al. 1984). 

In comparison to MR imaging, CT is inexpensive and easily available in most institutions. Therefore, most bone biopsies are performed under CT guidance. First, a CT scan is performed in order to visualize the bone lesion, and the needle entry point and access path are chosen. In cases of superficial bone biopsies without potential interference with vascular and nerve structures along the access path, a nonenhanced CT scan is usually sufficient for planning of the access route. Vessels, nerves, visceral, and articular structures should be avoided. Depending on the localization of the bone lesion, different approaches are available ... 

In comparison to conventional CT guidance, the advantage of CTF is the online visualization, the excellent resolution of bone, and the surrounding soft tissue and the possibility to target even small lesions (Daly and Templeton 1999). The very good resolution of bone and soft tissue is furthermore able to reduce the amount of complications due to misplacement of the needle. 

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