Spiral CT angiography and surgical correlations in the evaluation of intracranial aneurysms

We investigated the accuracy of spiral computed tomography angiography (CTA) in the detection and study of intracranial aneurysms by comparing CTA with selective angiograms and surgical findings. Twenty-six patients (9 men and 17 women; mean age 53.1 +/- 1.8 years) with suspected intracranial aneurysms were submitted to CTA (1- to 2-mm slices, pitch 1:1, 24 s, RI = 1) after a conventional CT examination showing subarachnoid hemorrhage (SAH) in 19 cases and during neuroradiological investigations performed for other reasons in 7 cases. One hundred twenty to 150 ml iodate contrast agent (0.3-0.4 gI/ml) were injected intravenously at 5 ml/s rate and with 12- to 25-s delay calculated with a preliminary test bolus. Three-dimensional shaded surface display (3D SSD) and maximum intensity projection (MIP) reconstructions were obtained from axial images. Then, within 48 h, all patients were submitted to digital subtraction angiography (DSA), with separate assessment of CTA and DSA findings. Twenty-two aneurysms shown by CTA were confirmed at DSA and surgery (true positives), whereas the vascular lesion was not confirmed at DSA in 2 cases (false positives). The presence of intracranial aneurysms was excluded at both CTA and subsequent DSA in 7 cases (true negatives) and there were no false negatives; sensitivity was 100 %, specificity 77.8 %, and diagnostic accuracy 93.5 %. Computed tomography angiography aneurysm location was confirmed at surgery in all cases, with very high accuracy in assessing the presence of an aneurysm neck (100 %). Computed tomography angiography accurately depicted the aneurysm shape in 20 of 22 cases, but failed to depict its multilobed nature in 2 cases. The mean aneurysm diameter calculated at CTA was 0.99 +/- 0.12 cm vs 1.09 +/- 0.11 cm at surgery (p < 0.01). The present results suggest that the high sensitivity of CTA, if confirmed by further studies, might help in avoiding having to resort to arteriography after negative CTA in SAH patients.     

Maximum intensity projection images in the detection of simulated pulmonary nodules by spiral CT

This study was undertaken to investigate the use of maximum intensity projection (MIP) images in the detection of pulmonary nodules by spiral CT (SCT). 40 pulmonary nodules of high density were created by endobronchial deployment of 2 and 4 mm beads in the peripheral airways of five anesthetized dogs. Standard SCT was performed with 5 mm collimation, pitch 2 and reconstruction of contiguous slices. MIP images were generated from overlapped slabs of seven consecutive 3 mm slices, reconstructed at 2 mm intervals and acquired at pitch 2. Scans were reviewed by six radiologists. The data were modelled using ordinal logistic regression for repeated measures, and the Wald chi 2 statistic used to test if there was a difference in nodule detection and reader confidence level between the two techniques. MIP imaging increased the odds of nodule detection by 2.18 (p = 0.0002). Reader confidence level for nodule detection was significantly higher with MIP images (p < 0.00001). MIP images improve the detection rate for small high density pulmonary nodules and increase reader confidence level, when compared with standard SCT.     

Diagnostic impact of four postprocessing techniques in evaluating contrast-enhanced three-dimensional MR angiography

OBJECTIVE: The purpose of this study was to determine the added diagnostic value of various three-dimensional (3D) data viewing techniques when analyzing contrast-enhanced 3D MR angiography. MATERIALS AND METHODS: Twenty patients (mean age, 62 years) with symptomatic peripheral vascular disease were assessed with breath-hold, contrast-enhanced 3D MR angiography and catheter angiography, which served as the standard of reference. After an initial interpretation of the 3D MR angiographic data sets based only on standardized maximum intensity projections (MIP), the diagnostic gain of the stepwise addition of interactive multiplanar reformations, shaded-surface displays (SSD), and virtual intraarterial endoscopy (VIE) images was calculated. Time required for each step of postprocessing was measured. RESULTS: Pathologic changes were revealed by catheter angiography in 60 vascular segments (50 severe stenoses, seven aneurysms, and three occlusions). The average postprocessing times were MIP, 8 min (range, 5-12 min); multiplanar reformations, 9 min (range, 3-11 min); SSD, 15 min (range, 8-25 min); and VIE, 40 min (range, 18-63 min). Addition of multiplanar reformations to MIPs resulted in the greatest gain of diagnostic accuracy, from 92% to 96%, and diagnostic confidence. When analysis was based on all four techniques, receiver operating characteristic curve analysis revealed only minimal improvements in diagnostic confidence, whereas diagnostic accuracy remained unchanged at 96%. CONCLUSION: Accurate and time-effective analysis of contrast-enhanced 3D MR angiography should be based on MIP algorithms and multiplanar reformations. Additional evaluation with VIE or SSD techniques is time-consuming and provides little diagnostic gain.     

Pre-operative classification of abdominal aortic aneurysms with spiral CT: the axial source images revisited

OBJECTIVE: The differentiation of supra-, juxta- and high infrarenal abdominal aortic aneurysms (AAA), which is essential for good surgical management, remains problematic. This prospective study assessed the value of highly overlapping vs. contiguous axial spiral computed tomography (CT) reconstructions in the pre-operative assessment of AAA. PATIENTS AND METHODS: Thirty-five patients with abdominal aortic aneurysms were studied with spiral CT (10 mm collimation, pitch 1). Axial reconstructions were performed at 2 and 10 mm increments and compared with surgical findings. Using each protocol, the aneurysms were classified as infra-, juxta- or suprarenal. Observers also assessed visualization of main and accessory renal artery origins and identification of other surgically relevant vascular anomalies. RESULTS: The 2 mm protocol correctly identified 29/31 infrarenal, 3/3 juxtarenal and 1/1 suprarenal aneurysms; two infrarenal aneurysms were overestimated as suprarenal. The 10 mm protocol correctly classified 25/31 infrarenal, 3/3 juxtarenal and 1/1 suprarenal aneurysms; five infrarenal aneurysms were overestimated as juxtarenal (n = 3) or suprarenal (n = 2) and one case was equivocal. Correct classification was thus 94% using the 2 mm protocol and 83% with the 10 mm protocol (P = 0.063). All 70 main renal artery origins were visualized with the 2 mm protocol, while the 10 mm protocol missed six (P = 0.03) The 2 mm protocol identified 10 accessory renal arteries, four of which were missed by the 10 mm protocol. Both protocols demonstrated five surgically relevant venous anomalies. CONCLUSION: Spiral CT with highly overlapping axial reconstructions correctly classified 94% of abdominal aortic aneurysms; overlapping reconstructions were particularly useful in differentiating high infrarenal from juxtarenal aneurysms.     

Computed tomographic angiography for the evaluation of carotid artery stenosis

BACKGROUND AND PURPOSE: No previous study has compared the reliability of carotid artery measurement provided by axial images, shaded surface display (SSD), and maximum intensity projection (MIP). METHODS: Helical CT and conventional angiography were performed prospectively in 20 patients with atherosclerotic stenosis of the internal carotid artery. Stenosis measurement was performed in a blinded fashion on angiography and CT by two independent examiners. Calcifications were segmented when they were located far enough from the vascular lumen. SSD and MIP were systematically performed for each carotid bifurcation. We measured stenosis using conventional angiography as standard and the different CT reconstructions (axial images, SSD, and MIP) by comparing the stenosis diameter at its narrowest point to the normal internal carotid artery. The degree of stenosis was classified into six groups: no stenosis, mild stenosis (< 30%), moderate stenosis (30% to 70%), severe stenosis (> 70%), near occlusion, and occlusion (100%). No measurement was made in cases of normal artery, near occlusion, and occlusion. RESULTS: Correlations between angiography and the three types of reconstruction were very good. Axial sections correctly classified the carotid arteries in 95% of cases. In 10 carotid arteries, stenosis was not assessable by SSD and MIP because of calcifications. In the remaining carotid arteries, MIP correctly classified the degree of stenosis in 96% of cases, whereas SSD misclassified 21% of cases. CONCLUSIONS: Our study showed that axial images provide a reliable evaluation of carotid artery stenosis. Calcifications are limiting factors in SSD or MIP. When atherosclerotic plaques are not calcified, MIP reconstructions provide a more reliable measurement of the vascular lumen than SSD.     

Cerebral aneurysm associated with persistent primitive olfactory artery aneurysm

Persistent primitive olfactory artery is a rare vascular anomaly but has a clinical importance because of its high association with cerebral aneurysm. We describe a patient with bilateral persistent primitive olfactory arteries associated with an unruptured saccular aneurysm on the left persistent primitive olfactory artery. Seven reported cases with this anomalous artery including ours are reviewed and classified into two variants. This anomalous artery arises from the terminal portion of the internal carotid artery and courses anteromedially along the ipsilateral olfactory tract and makes a hair-pin curve posterior to the olfactory bulb, becoming the distal anterior cerebral artery (variant 1) or the ethmoidal artery (variant 2). Out of 7 reported cases, 4 cases are associated with saccular aneurysms. The aneurysm in variant 1 is located on the hair-pin curve at which an apparent arterial branch is sometimes absent. Two patients suffer from anosmia. Persistent primitive olfactory artery should be kept in mind because of its high association with intracranial saccular aneurysms and unique clinical presentation.     

Molecular analysis of the malR gene of Clostridium butyricum NCIMB 7423, a member of the LacI-GalR family of repressor proteins

OBJECTIVE: The purpose of our study was to evaluate helical CT using axial, coronal, and three-dimensional (3D) reconstruction in the examination of potential kidney donors and to compare the results with angiography and surgery when possible. We also reviewed previously published reports. SUBJECTS AND METHODS: Thirty-six patients underwent unenhanced and enhanced helical CT (3-mm collimation, 150-170 ml of i.v. contrast material injected at 4 ml/sec; pitch 1.5; 17-sec scan delay) with coronal and 3D shaded-surface-display reconstructions made from 1.5-mm overlapping reconstructions. All CT scans were interpreted independently of each other by two observers unaware of other findings. A third observer, who was aware of other findings, also interpreted the images. Results were compared with angiography (24 cases) and surgery (24 cases). Our results are compared with those of other investigators. RESULTS: Axial CT was the best method for detecting accessory arteries (24%) and early branching (10%); it also detected relevant venous and ureteral anatomy and incidental findings. The coronal and 3D images rarely added information that resulted in changed patient treatment. CT findings were concordant with those of digital angiography in 89% of kidneys and were 98% concordant with surgery. CONCLUSION: Helical CT can show arterial, venous, and ureteral anatomy and can also show important incidental findings. If only helical CT is used, a few small accessory vessels and an occasional renal artery stenosis may be missed. Axial images are generally diagnostic and may be supplemented by multiplanar and 3D images read concurrently.     

Methotrexate hepatotoxicity: what is the evidence?

PURPOSE: To assess the usefulness of fractal geometry in quantitatively evaluating the convergence of peripheral vessels on peripheral lung tumors in maximum intensity projection (MIP) images. MATERIALS AND METHODS: We studied the MIP images of 34 pathologically proved small peripheral lung tumors (lung cancer in 21, hamartoma in 13) in 34 patients. To obtain MIP images, spiral CT (SOMATOM PLUS; Siemens) was performed during a single breath hold (24-second scan time, 2-mm section thickness, and 2 mm/sec table feed time, reconstructed at 1-mm increments). To evaluate the convergence of the peripheral vessels and bronchi towards the tumor, we fixed a region of interest (ROI) on the hilar side of the lung tumor, parallel to the chest wall, which consisted of 64 x 64 square pixels, in the images that divided at the center of the window width. We counted the overlapping pixels by the two-dimensional box-counting method and obtained fractal dimensional data on lung cancers and hamartomas. RESULTS: There was a statistically significant difference in the fractal dimension (D) between lung cancers (D = 1.81 +/- 0.13) and hamartomas (D = 1.67 +/- 0.10) (P = 0.0067). CONCLUSION: Fractal geometry could be useful in the diagnosis of small peripheral lung tumors.     

Three-dimensional images of hepatic tumors and hepatic vessels obtained by helical computed tomography

Helical computed tomography was performed with intravenous contrast material administration in ten patients with hepatic tumors (metastatic tumor, n = 6; hepatocellular carcinoma, n = 4). Maximum intensity projection (MIP) images of intrahepatic portal venous branches and hepatic veins, and shaded surface display (SSD) images of the hepatic tumors were reconstructed for each patient. The MIP image and SSD image were fitted to overlap on a single display to obtain three-dimensional (3-D) images showing both the hepatic vessels and hepatic tumors. Subsegmental localization of the tumors determined from the 3-D images proved to be correct in all of the six patients who received hepatic resection after examination. 3-D images seem to be useful for preoperative assessment of hepatic tumors.     

Comparative evaluation of cerebral aneurysms with selective arterially enhanced CT and DSA

The purpose of our study was to compare selective arterially enhanced spiral computed tomographs (ACT) with digital subtraction angiographies (DSA) in the presurgical assessment of cerebral aneurysms. A total of 24 aneurysms in 18 patients were explored in a prospective study by ACT and DSA, using an interactive combined CT-angiography suite. Dimensions of the aneurysm, its relation to the parent vessel, and the aneurysmal index were defined on DSA and on surface-shaded display of 3D reformatted images obtained from ACT. Results were correlated with surgical findings. Three aneurysms suspected on DSA were not confirmed by ACT. One fusiform aneurysm suspected on DSA corresponded to a sacciform aneurysm on ACT. Surgical findings confirmed 20 sacciform aneurysms. The aneurysmal index could be measured in all 20 cases of sacciform aneurysms on ACT and could not be determined with confidence in 55 % of the cases on DSA. DSA and ACT gave identical results in 35 % of cases. In 10 %, the index measured by ACT was superior to that determined by DSA for aneurysms which had a diameter of less than 3 mm. In conclusion, the combination of DSA and ACT improved the results of DSA alone. ACT is a reliable method to measure the aneurysmal index in aneurysms with a diameter superior to 3 mm.     

Rupture of a previously documented small asymptomatic intracranial aneurysm in a patient with autosomal dominant polycystic kidney disease. Case report

Intracranial aneurysms are common extrarenal manifestations of autosomal dominant polycystic kidney disease (ADPKD). Although their natural history is not completely understood, small asymptomatic intracranial aneurysms in patients with ADPKD often are not treated but are followed with serial magnetic resonance (MR) angiography. The authors report the unique case of a patient with ADPKD who bled from a previously documented asymptomatic 3-mm intracranial aneurysm. This 42-year-old man with ADPKD suffered a subarachnoid hemorrhage (SAH) from a 7-mm left pericallosal artery aneurysm. This aneurysm was clipped and the patient made an excellent recovery. An irregular asymptomatic 3-mm right middle cerebral artery (MCA) aneurysm had also been demonstrated on angiography. While the patient was considering elective surgery for the MCA aneurysm, he suffered a hemorrhage from this lesion 10 weeks after the initial SAH. The aneurysm was clipped and the patient made a satisfactory recovery (he was moderately disabled). In this report the authors indicate that small asymptomatic intracranial aneurysms are not always innocuous in patients with ADPKD, and they suggest that treatment should be strongly considered for these lesions in this group of patients when there is a history of SAH or the aneurysm is irregular in appearance. Because MR angiography studies may not adequately define the configuration of small aneurysms and irregularity may easily be missed, conventional angiography is recommended for patients with ADPKD who are found to have an intracranial aneurysm on screening with MR angiography.     

Ghosting of pulmonary nodules with respiratory motion: comparison of helical and conventional CT using an in vitro pediatric model

OBJECTIVE: The study was designed to compare helical CT with varying pitch and reconstruction intervals and conventional CT for revealing pulmonary nodules in a model that simulates respiratory motion in children. MATERIALS AND METHODS: CT scans were obtained in an experimental model with one nodule (3 or 10 mm) in each scan. One-second scans were obtained at rates of 10, 20, and 30 respirations per minute using conventional CT with 4-mm collimation and table incrementation and helical CT with 4-mm collimation and either 4-mm/sec (pitch, 1:1) or 8-mm/sec (pitch, 2:1) table speed. Reconstructions were at 1-, 2-, and 4-mm intervals for scans obtained using 4-mm/sec table speed and at 1- and 4-mm intervals for scans obtained using 8-mm/sec table speed. Images were independently reviewed by three radiologists who estimated the number of nodules on each image. RESULTS: Ghosting (depiction of more than one nodule in a study) was seen in 79%, 80%, and 75% of helical CT scans obtained with a 1:1 pitch using 1-, 2-, and 4-mm reconstruction intervals, respectively. By comparison, ghosting was seen in only 54% and 58% of helical CT scans with a 2:1 pitch using 1-mm reconstruction intervals and 4-mm reconstruction intervals, respectively, and in 56% of conventional CT scans (p < .0001). A single nodule was detected on all other scans, and at least one nodule was seen on all scans. CONCLUSION: Ghosting of nodules is common in this model. Ghosting was seen less often on conventional scans and helical scans with 2:1 pitch than it was on helical scans with 1:1 pitch. Nonetheless, ghosting was seen on more than 50% of all scans with each technique.     

Risks and benefits of diagnostic angiography after aneurysm surgery: a retrospective analysis of 597 studies

INTRODUCTION: Cerebral angiography performed after aneurysm surgery can identify causes of morbidity and mortality that may be corrected. The risks and benefits of angiography that is performed after aneurysm surgery, however, have not been clearly defined. We therefore reviewed our experience with postoperative angiography to determine its dangers and benefits. METHODS: During 10 years, 543 consecutive patients received treatment for cerebral aneurysms. A retrospective analysis of 597 diagnostic angiograms obtained after aneurysm surgery for 494 of these patients was performed. RESULTS: Catheter-induced vessel spasm and dissection, occurring most frequently in the internal carotid artery, were observed in seven (1.2%) and six (1%) studies, respectively. No angiography-associated strokes were identified. No association between age, smoking, hypertension, blood pressure, atherosclerosis, or severe vasospasm and angiographic complications was observed. Aneurysm remnants were identified in 36 (5.7%) of the 637 aneurysms that were surgically treated. Atherosclerosis (P < 0.01) or multiple clip applications (P < 0.01) were significantly associated with aneurysm remnants. Angiographic vessel occlusion was observed in 28 (5.7%) patients and resulted in stroke in 14 of these patients. Vessel occlusion was significantly associated with increasing aneurysm size (P < 0.001), atherosclerosis (P < 0.001), temporary clips (P < 0.001), multiple clips (P=0.03), multiple clip applications (P=0.001), and a new postoperative neurological deficit (P=0.002). Severe vasospasm and newly identified aneurysms were observed in 51 and 16 patients, respectively. CONCLUSION: Angiography after aneurysm surgery is safe and can be routinely performed. Angiography after aneurysm surgery should be particularly considered for patients with large aneurysms or cerebrovascular atherosclerosis and for those who develop new postoperative neurological deficits.     

Little known pages from the history of discovering tick-borne encephalitis

The purpose of this study was to evaluate the clinical usefulness of three-dimensional CT angiography (3D-CTA) for the diagnosis of cerebral aneurysm using a new reconstruction method called Multi-Angle Reconstruction Plan (MARP). The threshold values, region of interest and six angles of view were preset for the MARP method on the basis of our experience with cerebral 3D-CTA. Spiral CT angiography was performed in 27 patients with 29 aneurysms. The six images reconstructed with the MARP method were generated from the volumetric CT data. Two radiologists independently reviewed the six 3D-CT images for the presence of aneurysm. It took about five minutes to semiautomatically reconstruct the six 3D-CT images with the MARP method. There were no discrepancies in the evaluation of the 3D-CT images. Twenty-six aneurysms of 24 patients were demonstrated on the six 3D-CT images. Three aneurysms in 3 patients were not depicted on the 3D-CT images by the MARP method. In them, the additional 3D-CT images which were generated after evaluating the 2D-CT images clearly showed the aneurysms. The MARP method is considered to be a useful three-dimensional reconstruction technique for the diagnosis of cerebral aneurysm.     

The genomic organization of the genes for human lipopolysaccharide binding protein (LBP) and bactericidal permeability increasing protein (BPI) is highly conserved

PURPOSE: The authors evaluated computed tomographic (CT) virtual colography for the detection of simulated polyps under ideal conditions, as well as the effects on lesion conspicuity of (a) collimation, (b) table pitch, and (c) orientation of the colon lumen with respect to the gantry. MATERIALS AND METHODS: Pig colon was resected and cleansed, and polyps with diameters of 3, 7, and 10 mm were created. Each specimen was scanned with collimation of 5 and 7 mm and table pitch of 1.0, 1.6, and 2.0 at angles of 0 degrees, 45 degrees, and 90 degrees to the gantry. The initial two-dimensional (2D) images were reconstructed at 1-mm intervals (2D reconstructions), from which three-dimensional (3D) virtual colography images were generated. Polyp conspicuity on the initial and reconstructed 2D images and the 3D reconstructions was evaluated on a three-point scale: 0 = polyp not depicted, 1 = polyp faintly depicted, and 2 = polyp clearly depicted. RESULTS: The 10-mm-diameter polyp was clearly depicted (grade 2 conspicuity) on every initial and reconstructed 2D image and 3D reconstruction without regard to collimation, table pitch, or angle to the gantry. The 7-mm-diameter polyp was clearly depicted (grade 2 conspicuity) on every initial and reconstructed 2D image, but conspicuity on 3D reconstructions varied as the imaging parameters varied. The 3-mm-diameter polyp was faintly depicted (grade 1 conspicuity) on the initial and reconstructed 2D images and 3D reconstructions, but conspicuity varied on the 3D reconstructions as the imaging parameters varied. CONCLUSION: CT virtual colography helped detection of small mucosal polyps regardless of the angle of the colon lumen to the gantry at which they were obtained.     

Experience with computed tomographic angiography for the detection of intracranial aneurysms in the setting of acute subarachnoid hemorrhage

OBJECTIVE: To objectively compare computed tomographic angiography (CTA) with selective digital subtraction angiography (DSA) in the detection and anatomic definition of intracranial aneurysms, particularly in the setting of acute subarachnoid hemorrhage (SAH). METHODS: In a blinded prospective study, 40 patients with known or suspected intracranial saccular aneurysms underwent both CTA and DSA, including 32 consecutive patients with SAH in whom CTA was performed after CT images were obtained diagnostic for SAH. The CT angiograms were interpreted for presence, location, and size of the aneurysms, and anatomic features, such as the number of aneurysms lobes, aneurysm neck size (< or = 4 mm), and the number of adjacent arterial branches were suggested. The images obtained with CTA were then compared with the images obtained with DSA, with the later images serving as controls. RESULTS: DSA revealed 43 aneurysms in 30 patients and ruled out intracranial aneurysms in the remaining 10 patients. For aneurysm presence alone, the sensitivity and specificity for CTA was 86 and 90%, respectively. For the presence of an aneurysms, six CT angiogram showed false negative results and one CT angiogram showed a false positive result. False negative results were usually caused by technical problems with the image, tiny aneurysm domes (< 3 mm), and unusual aneurysm locations (i.e., intracavernous carotid or posterior inferior cerebellar artery aneurysms). The results obtained with CTA were, compared with the results obtained with DSA, more than 95% accurate in determining dome and neck size of aneurysm, aneurysm lobularity, and the presence and number of adjacent arterial branches. In addition, CTA provided a three-dimensional representation of the aneurysmal lesion, which was considered useful for surgical planning. CONCLUSION: CTA is useful for rapid and relatively noninvasive detection of aneurysms in common locations, and the anatomic information provided in images showing positive results is at least equivalent to that provided by DSA. In cases of SAH in which the nonaugmented CT and CTA results indicate a clear source of bleeding and provide adequate anatomic detail, we think it is possible to forego DSA before urgent early aneurysm surgery. In all other cases, DSA is indicated.     

Optimization and diagnostic accuracy of computerized tomography with tridimensional spiral technique in the study of craniostenosis

INTRODUCTION: Conventional Computed Tomography (CT) with three-dimensional (3D) reconstructions is considered the most complete and accurate imaging modality to diagnose craniosynostosis. However, the introduction of Spiral CT (SCT) opened new possibilities for 3D studies of the skull in pediatric patients with craniosynostosis. The purpose of our study is two fold: first, to optimize the scanning and imaging parameters to obtain diagnostic images in a single spiral scan; second, to assess the diagnostic accuracy of such images in the identification of normal and abnormal cranial vault sutures. MATERIAL AND METHODS: Seventy-eight pediatric patients (age range: 1-35 months; mean: 11.8 months) with craniosynostosis were submitted to SCT of the head. The images were acquired with the following parameters: 3- and 5-mm nominal slice thickness, 5-6 mm/s table feed (pitch 1-2), 165 mAs and 120 kV. Two different algorithms and increases were used for image reconstructions. A first set of images was reconstructed with 2-mm increases and a soft tissue algorithm: these images were used for brain studies and for 3D reconstructions. A second set of slices was reconstructed with 5-mm increases and a bone algorithm to visualize the sutures of the axial plane. The 3D images were processed with the Shaded Surface Display software with threshold values ranging 120-150 HU. All images were acquired with a single spiral scan lasting less than 30 seconds. Two blinded radiologists analyzed the 3D and the planar images independently to evaluate the course and depth of each cranial suture. The sensitivity, specificity and diagnostic accuracy of both 3D and planar SCT images were evaluated. The frequency of artifacts (the Lego effect, boiled egg, pseudoforamina, movement, and chainsaw artifacts) and their influence on the final diagnosis were studied on 3D SCT images. RESULTS: The diagnostic accuracy rates of 3D SCT images, by suture, were: sagittal 90.7%, metopic 100%, left lamboid 90.9%, right lamboid 93.9%, left coronal 85.7%, right coronal 91.1%. The diagnostic accuracy rates of the axial images, by suture, were: sagittal 90.7%, metopic 95.5%, left lamboid 86.4%, right lamboid 90.9%, left coronal 83.7%, right coronal 91.1%. The interobserver agreement on 3D images was: sagittal 91.1%, metopic 100%, left lamboid 88.9%, right lamboid 91.1%, left coronal 88.9%, right coronal 84.4%. The Lego effect artifact was the most frequent one (82%) and affected image evaluation in 6.3% of cases. CONCLUSIONS: Our results prove that 3D SCT is a very accurate technique for identifying normal and abnormal sutures and presents many advantages over conventional 3D CT in the examination of pediatric patients with craniosynostosis. The quality of 3D SCT images was adequate and the artifacts did not affect the final diagnostic yield significantly.     

Spiral CT. Better resolution by increased pitch?

The longitudinal resolution of spiral CT has been investigated in dependence on table increment and beam collimation by use of a phantom. The results show clearly that the pitch (ratio of table increment per tube rotation to beam collimation) alone does not allow one to draw any conclusions about the resolution. Thus, a large pitch can yield a better resolution than the pitch of 1. The individual parameters table increment and beam collimation are more relevant with regard to the resolution than the rate of pitch. An alteration of the pitch can be achieved in two different ways. An increase of the pitch by a decreased beam collimation improves the resolution. In contrast, an increase of the pitch by an increased table increment decreases the resolution. A good spatial resolution of objects with high contrast (bone, lung, enhanced vessels) needs a narrow beam collimation, even if a pitch as high as 2 is necessary for a given scanning coverage. A large pitch does not cause gaps in the data set. Moreover, the patient's radiation dose decreases.     

Saccular aneurysms of meningeal artery: case report

OBJECTIVE AND IMPORTANCE: A rare observation of double saccular aneurysms of the meningeal artery is presented. CLINICAL PRESENTATION: This 22-year-old man was referred to the Neurosurgical Institute with a suspicion of an aneurysm of the anterior communicating artery. Bilateral angiography of the carotid arteries was performed 1 week after the subarachnoid hemorrhage, but the aneurysms were not visualized. Routine angiography of both carotid arteries and selective studies of the left vertebral artery were performed again, and angiography of the right carotid artery revealed an aneurysm. The patient's neurological state at the time of admission was normal. Fundoscopic examination revealed papilledema and conjunctival injection of the left eye. INTERVENTION: The patient was treated using a right pterional approach. One aneurysm had caused spontaneous subarachnoid hemorrhage. The aneurysms were removed using a direct approach, with histological examination of dura matter fragment containing both aneurysms. The results of the patient's 2-week follow-up examination were normal. Follow-up angiography of the right carotid artery showed absence of the aneurysm with a clip on the branch of meningeal artery. CONCLUSION: Saccular aneurysms of the meningeal artery can be manifested by subarachnoid hemorrhage, and intradural arterial aneurysms are similar to saccular cerebral vessel lesions structurally.     

Impact of scale standardization on images of digital radiography systems

OBJECTIVES: To test the effect of altering image size on diagnostic quality. METHODS: Endodontic files, size 10 and 15 were prepared to full root length and 1.5 mm short, in upper and lower molars and premolars. Digital images of the Sidexis (S) and Visualix/Vixa (V) system were reduced in size to Digora (D) scale, and the D images were enlarged to S scale. ROC analysis was performed and data analysed with MANOVA statistics. RESULTS: Assessment of root canal length with file size 10 was less accurate for the S images reduced in size, compared with the original S images (P < 0.011). All other differences were not significant (P > 0.081). CONCLUSIONS: Relevant diagnostic information may be lost when images are reduced in size. Therefore, for optimal presentation, the smaller images should be enlarged rather than the larger ones reduced.