Pitfalls in the use of Multidetector Row CT Angiography for Identification of Intracranial Vascular Abnormalities : Focus on the Various Radiological Findings / 대한뇌혈관외과학회지

OBJECTIVE: Multidetector-Row computed tomographic angiography (MDCTA) is a promising method for detection and surgical planning of intracranial vascular abnormalities. However, there are several problems, such as image degradation due to inevitable patients movement, venous contamination, kissing vessel artifact, demonstration of venous structures mimicking aneurysm and bone artifacts. The purpose of our study is to review our recent experience with false negative or positive cases on MDCTA. METHODS: Between May 2007 and May 2010, 259 consecutive patients, who were diagnosed with intracranial aneurysms or other vascular abnormalities by MDCTA, were retrospectively reviewed. Among the 259 patients, 172 patients who underwent digital subtraction angiography (DSA), which was considered as the standard of reference, were included in the study. Two neuroradiologists and two neurosurgeons evaluated independently and separately all of the MDCTA images. RESULTS: A total 26 cases (15.3%) were revealed abnormal vascular findings on MDCTA. There were 11 false negatives on MDCTA including incomplete scanning range of lesion site (n=3), a blood blister aneurysm (n=1), severe vasospasm (n=4) and bone artifacts (n=3). Also there were 15 false positives on MDCTA; venous contamination over the lesion site (n=6), focal dilation of the bifurcation or branching site of major vessels (n=6) and poor quality of the images due to inevitable patients movement (n=3). CONCLUSIONS: MDCTA is clearly not the total answer for aneurysm diagnosis. We recommend that MDCTA scanning range is planned to encompass the whole intracerebral vasculature. Close attention to image acquisition and interpretation are required to reduce errors in MDCTA of intracranial aneurysms.

Myocardial Bridging of the Left Anterior Descending Coronary Artery: Depiction Rate and Morphologic Features by Dual-Source CT Coronary Angiography

OBJECTIVE: To evaluate the depiction rate and morphologic features of myocardial bridging (MB) of the left anterior descending coronary artery (LAD) using dual-source CT (DSCT). MATERIALS AND METHODS: CT scans from a total of 1,353 patients who underwent DSCT were reviewed retrospectively for LAD-MB. Seventy-eight patients were excluded due to poor image quality or poor enhancement of the coronary artery. The length and depth of the MB were analyzed and classified as superficial or deep with respect to the depth ( 1 mm) of the LAD tunneled segment. Superficial MB was subdivided into complete or incomplete types according to full or partial encasement of the myocardium. RESULTS: Of the 1,275 patients included in this study, 557 cases of MB were found from 536 patients (42%). Superficial MB was observed in 368 of 557 (66%) cases, and deep MB was seen in 189 of 557 (34%) cases. Superficial MB showed 2 types: complete (128 of 368, 35%) and incomplete (240 of 368, 65%). The mean length of a tunneled segment for superficial MB was 16.4 +/- 8.6 mm. The mean length and depth of a tunneled segment for deep MB were 27.6 +/- 12.8 mm and 3.0 +/- 1.4 mm, respectively. The incidence of atherosclerotic plaques in a 2-cm-long segment proximal to MB was 16%. CONCLUSION: The depiction rate of LAD-MB using DSCT in a large series of patients was 42%, with two-thirds of MB segments being the superficial type.

Conventional Angiogram versus Multi-detector Row Helical Computed Tomography Angiogram for Preoperative Diagnostic Imaging in Low Extremity Arterial Surgery

PURPOSE: We performed this study to assess the suitability of conventional angiography (CA) vs. multi-detector row helical CT angiogram (MD-CTA) as a method of preoperative diagnostic imaging for low extremity arterial surgery. METHODS: From February 2004 to September 2006, 23 patients (4 claudicants, 19 limb-threatening ischemia) were studied with CA and MD-CTA preoperatively. The site and degree of stenotic or occlusive lesions in arterial segments from the renal artery to the dorsalis pedis artery were compared with both methods. We also compared the surgical inflow and outflow site changes in preoperative planning based on CA and MD-CTA and the final outcome. Additional diagnostic value and test-related complications were also analyzed. RESULTS: The median age of patients was 68 years old (range: 43~89 years), with a male to female ratio of 1.3:1. Twenty-three patients had CA after an MD-CTA scan. One hundred fifty lesions were detected in these patients. The total ratio of consistency for occlusion in CA vs. MD-CTA was 69.6%. Three patients received amputation treatment and eleven patients received a bypass operation. The agreement between the preoperative plan based on MD-CTA and the final operation was 100%, even in critical limb ischemia. There were no serious complications related to the tests. CONCLUSION: These findings suggest that MD-CTA is an adequate preoperative imaging study of infrainguinal arterial surgery and may be substituted for conventional angiography without any serious complications.

Diagnostic accuracy of 64-slice multi-detector CT coronary angiography in the evaluation of coronary artery disease / 대한내과학회지

Conventional coronary angiography (CCA) has been the gold standard for the detection of significant coronary artery disease (CAD). However, CCA is invasive and 2/3 of all CCA have been performed for the diagnosis of significant stenosis without intervention. Recently, the use of multi-detector CT (MDCT) coronary angiography has been rapidly evolving as a promising non-invasive method for the assessment of patients with CAD. With the advent of 64-slice MDCT scanner, both temporal and spatial resolutions of coronary CT angiography have further improved for the non-invasive detection of coronary stenoses. The diagnostic performance for the assessment of CAD has significantly improved, and the nonassessable proportion of segments significantly decreased with the newer generations of MDCT scanners. Namgung et al. reported that high diagnostic accuracy for 64-slice MDCT in the detection of significant stenosis (> or =50% lumen diameter narrowing) on per segment (96% sensitivity and 97% specificity), per vessel (96% sensitivity and 97% specificity), and per patient analyses (100% sensitivity and 94% specificity). The negative predictive value for classification of segments, vessels, and patients with or without CAD was very high (99-100%). These findings indicate that 64-slice MDCT coronary angiography can be reliable as a gatekeeper of CCA in selected groups of patients.

Comparative Study of Angiography and Magnetic Resonance Image in Verifying Obliteration of Arteriovenous Malformation after Gamma Knife Radiosurgery

OBJECTIVE: The purpose of this study is that magnetic resonance(MR) imaging can substitute for conventional angiography in verifying obliteration of arteriovenous malformation(AVM) after Gamma Knife radiosurgery. METHODS: Among the patients of AVM treated with Gamma Knife between 1992 and 1997, all of 40 patients who had been followed up more than 2 years(range 24-101 months) had no AVM on follow-up MR images. Follow-up imaging was performed every 6 months or when clinically warranted. Conventional angiography was performed when the AVM was no longer seen on MR images. RESULTS: Among 40 patients who had shown total obliteration on MR images, thirty one patients(77.5%) showed complete obliteration of the lesion on angiography. However, subtotal obliteration was shown in five patients(12.5%) and partial obliteration in four patients(10.0%). CONCLUSION: The conventional angiography is absolutely needed for verifying obliteration of AVMs and to eliminate the misunderstanding of follow-up MR images.

Is Conventional Angiography Always Superior to MR Angiography in Evaluatin of Cerebral Aneurysm?

Conventional angiography still remains the procedure of choice in evaluation of cerebral aneurysm. However, MRI and MR angiography can play different roles in vizualizing cerebral aneurysm. A 43-year-old male was evaluated for recurrent seizure attacks. The brain MRI showed non-enhancing iso-signal mass on T1WI, signal voiding mass with stalk-like structure on coronal T2WI in the right temporal region. MRA also revealed dark round signal. However, the conventional cerebral angiography failed to visualize it. Finally, the mass was confirmed as a huge aneurysm filled with intraluminal thrombus on operation. It should seem that contrast media could not fill the aneurysmal sac because of intraluminal thrombus in conventional angiography. But aneurysmal sac seemed to be visible on MRA as paramagnetic artifact of thrombus. So, it can be assumed that MRA is superior to the conventional angiography in some cases of cerebral aneurysm, especially when it is associated with intraluminal thrombus.

Comparison between CT Angiography and Conventional Angiography in the Diagnosis of Intracrnial Aneurysms

Cerebral angiography has been essential for the diagnosis of the intracranial aneurysms but, is sometimes accompanied by serious complications. Resolution of CT angiography was up-graded greatly to represent the three-demensional structure of vessels since helical CT had been introduced. We have compred 26 cases of CT angiography and 28 cases of conventional angiography in terms of specificity and sensitivity for the diagnosis, detectable aneurysm diameter, configurational diagnosis and diagnostic confidency. All results showed no statistical difference between CT angiography and conventional angiography. These should suggest that CT angiography could be replaced with conventional angiography for the diagnosis of ruptured aneurysms and even of unruptured aneurysms, resulting in the introduction of first screening modality of unruptured aneurysms.

Comparison between CT Angiography and Conventional Angiography in the Diagnosis of Intracrnial Aneurysms

Cerebral angiography has been essential for the diagnosis of the intracranial aneurysms but, is sometimes accompanied by serious complications. Resolution of CT angiography was up-graded greatly to represent the three-demensional structure of vessels since helical CT had been introduced. We have compred 26 cases of CT angiography and 28 cases of conventional angiography in terms of specificity and sensitivity for the diagnosis, detectable aneurysm diameter, configurational diagnosis and diagnostic confidency. All results showed no statistical difference between CT angiography and conventional angiography. These should suggest that CT angiography could be replaced with conventional angiography for the diagnosis of ruptured aneurysms and even of unruptured aneurysms, resulting in the introduction of first screening modality of unruptured aneurysms.

Diagnostic Value of Three-Dimensional Computed Tomographic Angiography(3-DCTA) in Intracranial Aneurysm

The authors have evaluated the efficacy of three dimensional computed tomographic angiography(3-DCTA) in diagnosing intracranial aneurysm. This literature studied thirty five patients harboing forty intracranial aneurysms using dynamic CT scan with intravenous contrast enhancement. After injection of 2 mg/kg of nonionic contrast material(RayvistR) intravenously, rapid dynamic CT scanning with thin section was performed. Three dimensional reconstruction was performed using the GE 9800 HR surface-rendering method with a threshold of about 100 Hounsfield units(HU). The authors comparatively analysed this 3-DCTA with conventional cerebral angiography to determine aneurysmal detection, shape, direction, and its relationships to surrounding vessels. While 3-DCTA clearly detected 38 aneurysms, conventional angiography did 37 ones. There was no significant difference between 3-DCTA and conventional angiography in demonstrating aneurysmal direction, but 3-DCTA was superior to conventional angiography in demonstrating aneurysmal shape, its neck and surrounding vascular structures. 3-DCTA showed deliberate anatomy of aneuysm and adjacent vessels through 3 dimensional image, and its operative view is helpful in surgical planning. 3-DCTA might be expected to substitute for conventional angiography in the near future.

Clinical Applications of Digital Subtraction Angiography(DSA) in Neurosurgical Field

Methods for the identification and amplification of signals from quantities of intravascularly administered iodinated contrast agent and their combination with image subtraction have evolved into a clinically useful technique called digital subtraction angiography (DAS). The initial motivation for the development of DSA was the desire to replace standard conventional angiographic procedures with simpler, less invasive techniques. We have evaluated IV-DSA and IA-DSA which are made in 150 patients with clinically suspected intracranial diseases from Dec. 1983 to Mar. 1985. Comparison with IA-DSA and conventional angiography indicated that the quality and information of content of the film were equivalent. IV-DSA image quality was inferior to that of conventional angiography. But IV-DSA can be used for intracranial studies to evaluate results of surgery of aneurysm, AVM or tumor and to revaluate vasospasm after subarachnoid hemorrhage before surgery. Also, IV-DSA can be used for neck vessel appearance due to reveal adequate information.