ABSTRACT
Orthopedic hardware should not be considered a contraindication to computed tomography (CT) or magnetic resonance (MR) imaging. The hardware alloy, the geometry of the hardware, and the orientation of the hardware all affect the magnitude of image artifacts. For commonly encountered alloys, the severity of image artifacts is similar for CT and MR. Cobalt chrome or stainless steel hardware produces the most artifacts; titanium hardware produces the least. In general, image artifacts are most severe adjacent to the hardware. CT image artifacts are related to incomplete X-ray projection data resulting in streaks. These can be mitigated by increasing scan technique and using a smoother reconstruction filter. Hardware with a rectangular cross-sectional shape such as a fixation plate will cause more artifacts than a radially symmetrical device such as an intramedullary nail. Image artifacts at MR are caused by the hardware magnetic susceptibility and the induction of eddy currents within the metal. A turbo spin-echo sequence yields the best results. The use of larger image matrices, thinner slices, and a wide receiver bandwidth are recommended parameter adjustments when imaging patients with hardware. This article discusses how hardware-related artifacts can be minimized by altering scan technique and image reconstruction.
Subject(s)
Artifacts , Image Interpretation, Computer-Assisted/methods , Magnetic Resonance Imaging/methods , Musculoskeletal Diseases/surgery , Postoperative Complications/diagnosis , Prostheses and Implants , Tomography, X-Ray Computed/methods , Humans , Metals , Postoperative PeriodABSTRACT
OBJECTIVE: To compare the safety and patient-reported effectiveness of two regimens for conscious sedation during enteroclysis. MATERIALS AND METHODS: We surveyed two groups of outpatients and retrospectively reviewed procedure records for conscious sedation and complications. Patients were divided into Group One (received sedative/amnesic diazepam), and Group Two, (received amnesic/sedative, midazolam and analgesic fentanyl). RESULTS: All enteroclyses were successfully completed; there were no hospital admissions due to complications. In Group One (n=106), mean dose of diazepam was 12.7 mg. 25% had oxygen desaturation (n=25), and post-procedure vomiting without aspiration (n=1). 56% of outpatients completed phone surveys, and 68% recalled procedural discomfort. In Group Two (n=45), mean doses were 3.9 mg midazolam and 108 mcg fentanyl. 31% had desaturation (n=13), and post-procedure vomiting without aspiration (n=1). 87% had only a vague recall of the procedure or of any discomfort. CONCLUSION: A combination of amnesic and fentanyl prevented the recall of discomfort of nasoenteric intubation and infusion in most patients who had enteroclysis compared to diazepam. Most of the patients would undergo the procedure again, if needed.
Subject(s)
Conscious Sedation/methods , Diazepam/administration & dosage , Fentanyl/administration & dosage , Intestines/diagnostic imaging , Midazolam/administration & dosage , Adult , Aged , Aged, 80 and over , Female , Humans , Hypnotics and Sedatives/administration & dosage , Male , Middle Aged , Radiography , Treatment OutcomeABSTRACT
A 40-year-old male with alcoholic cirrhosis and portal hypertension presented with acute variceal hemorrhage. Abdominal CT scan and endoscopy revealed large gastric varices. The patient underwent a TIPS procedure. Portal venography demonstrated persistent filling of the large gastric varices with associated high-flow spontaneous splenorenal shunt. Because of the large size of the varices, a Simon-Nitinol filter was used in conjunction with multiple embolization coils to enable successful occlusion of the varices.
