Detection of intracranial aneurysms with 64 channel multidetector row computed tomography: Comparison with digital subtraction angiography

Cerebrovascular Complication and Valve Surgery in Infective Endocarditis

Infective endocarditis (IE) with neurologic complications is common in patients with active IE. The most common and feared neurological complication of left-sided IE is cerebrovascular, from septic emboli causing ischemic stroke, intracranial hemorrhage (ICH), or an infectious intracranial aneurysm with or without rupture. In patients with cerebrovascular complications, valve replacement surgery is often delayed for concern of further neurological worsening. However, in circumstances when an indication for valve surgery to treat IE is present, the benefits of early surgical treatment may outweigh the potential neurologic deterioration. Furthermore, valve surgery has been associated with lower in-hospital mortality than medical therapy with intravenous antibiotics alone. Early valve surgery can be performed within 7 days of transient ischemic attack or asymptomatic stroke when medically indicated. Timing of valve surgery for IE after symptomatic medium or large symptomatic ischemic stroke or ICH remains challenging, and current data in the literature are conflicting about the risks and benefits. A delay of 2 to 4 weeks from the time of the cerebrovascular event is often recommended, balancing the risks and benefits of surgery. The range of timing of valve surgery varies depending on the clinical scenario, and is best determined by a multidisciplinary decision between cardiothoracic surgeons, cardiologists, infectious disease experts, and vascular neurologists in an experienced referral center.

Splenosis of the abdomen and pelvis complicated by torsion of a splenic implant clinically mimicking an acute bowel ischemia

We present a case of splenosis of the abdomen and pelvis complicated by torsion of a splenic implant in a young female patient clinically mimicking an acute bowel ischemia. Splenosis is a benign condition defined as heterotopic auto-transplantation of splenic tissue throughout different body areas. It may occur after rupture of the spleen, either traumatic or secondary to surgical procedures. Although the presence of heterotopic splenic tissue is often asymptomatic and an incidental finding, it may present with sudden abdominal pain and bleeding. CT and MRI play a critical role in the detection of splenosis-related complications, such as torsion of the vascular pedicle and infarction. Splenosis torsion is extremely rare and it is still a diagnostic dilemma; the complication of abdominal splenosis should be considered in the differential diagnosis in patients with previous splenectomy.

Optimal scan timing for artery-vein separation at whole-brain CT angiography using a 320-row MDCT volume scanner

OBJECTIVE

A 320-row multidetector CT (MDCT) is expected for a good artery-vein separation in terms of temporal resolution. However, a shortened scan duration may lead to insufficient vascular enhancement. We assessed the optimal scan timing for the artery-vein separation at whole-brain CT angiography (CTA) when bolus tracking was used at 320-row MDCT.

METHODS

We analyzed 60 patients, who underwent whole-brain four-dimensional CTA. Difference in CT attenuation between the internal carotid artery (ICA) and the superior sagittal sinus (D_att) was calculated in each phase. Using a visual evaluation score for the depiction of arteries and veins, we calculated the difference between the mean score for the intracranial arteries and the mean score for the veins (D_score). We assessed the time at which the maximum D_att and D_score were simultaneously observed.

RESULTS

The maximum D_att was observed at 6.0 s and 8.0 s in the arterial-dominant phase and at 16.0 s and 18.0 s in the venous-dominant phase after the contrast media arrival time at the ICA (T_aa). The maximum D_score was observed at 6.0 s and 8.0 s in the arterial-dominant phase and at 16.0 s in the venous-dominant phase after the T_aa. There were no statistically significant differences in D_att (p = 0.375) or D_score (p = 0.139) between these scan timings.

CONCLUSION

The optimal scan timing for artery-vein separation at whole-brain CTA was 6.0 s or 8.0 s for the arteries and 16.0 s for the veins after the T_aa. Advances in knowledge: Optimal scan timing allowed us to visualize intracranial arteries or veins with minimal superimposition.

Accuracy of 320-detector row nonsubtracted and subtracted volume CT angiography in evaluating small cerebral aneurysms

OBJECTIVE The study aimed to assess the diagnostic accuracy of 320-detector row nonsubtracted and subtracted volume CT angiography (VCTA) in detecting small cerebral aneurysms (< 3 mm) compared with 3D digital subtraction angiography (3D DSA). METHODS Six hundred sixty-two patients underwent 320-detector row VCTA and 3D DSA for suspected cerebral aneurysms. Five neuroradiologists independently reviewed VCTA and 3D DSA images. The 3D DSA was considered the reference standard, and the sensitivity, specificity, and accuracy of nonsubtracted and subtracted VCTA in depicting small aneurysms were analyzed. A p value < 0.05 was considered a significant difference. RESULTS According to 3D DSA images, 98 small cerebral aneurysms were identified in 90 of 662 patients. Nonsubtracted VCTA depicted 90 small aneurysms. Ten small aneurysms were missed, and 2 small aneurysms were misdiagnosed. The missed small aneurysms were located almost in the internal carotid artery, near bone tissue. The sensitivity, specificity, and accuracy of nonsubtracted VCTA in depicting small aneurysms were 89.8%, 99.2%, and 96.5%, respectively, on a per-aneurysm basis. Subtracted VCTA depicted 97 small aneurysms. Three small aneurysms were missed, and 2 small aneurysms were misdiagnosed. The sensitivity, specificity, and accuracy of subtracted VCTA in depicting small aneurysms were 96.9%, 99.2%, and 98.6%, respectively, on a per-aneurysm basis. There was no difference in accuracy between subtracted VCTA and 3D DSA (p = 1.000). However, nonsubtracted VCTA had significantly less sensitivity than 3D DSA and subtracted VCTA (p = 0.039 and 0.016, respectively). CONCLUSIONS Subtracted 320-detector row VCTA is sensitive enough to replace 3D DSA in the diagnosis of small cerebral aneurysms (< 3 mm). The accuracy rate of nonsubtracted VCTA was lower than that of subtracted VCTA and 3D DSA, especially in the assessment of small internal carotid artery aneurysms adjacent to the skull base.

Diagnostic Impact of Bone-Subtraction CT Angiography for Patients with Acute Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Detection and evaluation of ruptured aneurysms is critical for choosing an appropriate endovascular or neurosurgical intervention. Our aim was to assess whether bone-subtraction CTA is capable of guiding treatment for cerebral aneurysms in patients with acute SAH and could replace DSA.

MATERIALS AND METHODS

We prospectively studied 116 consecutive patients with SAH with 16-detector row bone-subtraction CTA and DSA before intracranial aneurysm treatment. Two independent neuroradiologists reviewed the bone-subtraction CTA blinded to DSA (reference standard). We determined the accuracy of bone-subtraction CTA for aneurysm detection and the measurement of aneurysm dimensions and compared the radiation doses of the 2 imaging modalities.

RESULTS

Seventy-one patients (61%) had 74 aneurysms on DSA. Bone-subtraction CTA detected 73 of these aneurysms, but it detected 1 additional aneurysm. On a per-aneurysm basis, sensitivity, specificity, and positive and negative predictive values for bone-subtraction CTA were 99%, 98%, and 99% and 98%, respectively. For aneurysms of ≤3 mm, sensitivity was 94% (95% CI, 73%-99%). Bone-subtraction CTA slightly overestimated neck and dome diameters by <0.2 mm and overestimated the dome-to-neck ratios by 2% on average. Dose-length product was 565 ± 201 mGy × cm for bone-subtraction CTA and 1609 ± 1300 mGy × cm for DSA.

CONCLUSIONS

Bone-subtraction CTA is as accurate as DSA in detecting cerebral aneurysms after SAH, provides similar information about aneurysm configuration and measures, and reduces the average effective radiation dose for vascular diagnostics by 65%. Diagnostic equivalence in association with dose reduction suggests replacing DSA with bone-subtraction CTA in the diagnostic work-up of spontaneous SAH.

CT angiography in non-traumatic subarachnoid hemorrhage: the importance of arterial attenuation for the detection of intracranial aneurysms

BACKGROUND

Computed tomography angiography (CTA) is today the primary method for the detection of intracranial aneurysms. The technique has evolved considerably during the last decade, and it is important to establish criteria for high image quality, especially with regard to improving the diagnosis of small aneurysms.

PURPOSE

To evaluate diagnostic accuracy and image quality by arterial attenuation of CTA in patients with non-traumatic subarachnoid hemorrhage (SAH).

MATERIAL AND METHODS

Between 2005 and 2011, CTA and digital subtraction angiography (DSA) were performed in 326 patients with non-traumatic SAH. Sensitivity and specificity for aneurysm detection were evaluated per patient, per aneurysm, and per ruptured aneurysm. The image quality of CTA was evaluated by arterial attenuation measurements (mean Hounsfield units [HU]) in the internal carotid artery (ICA).

RESULTS

In all, 285 aneurysms in 235 patients were detected by DSA, 19 aneurysms were missed on CTA, and 223 aneurysms were classified as ruptured. In 91 patients, no aneurysm was found. Correct diagnosis with CTA was made in 28 patients with perimesencephalic hemorrhage. Sensitivity and specificity (95% confidence interval) calculated per patient were 91.6% (87.3-94.9) and 87.9% (79.8-93.6), respectively, per aneurysm 93.3% (89.7-95.9) and 88% (79.9-93.6), and per ruptured aneurysm 94.9% (91.3-97.3) and 96.7% (90.7-99.3). Arterial attenuation (in HU) in CTA revealing true positive ruptured aneurysms and true negative aneurysms (mean 535 ± 110 HU) differed significantly (P = 0.02) from false negative ruptured aneurysms (mean 424 ± 30 HU).

CONCLUSION

CTA has high sensitivity and specificity for the detection of ruptured aneurysms. The sensitivity is related to arterial attenuation in the ICA.

Subarachnoid hemorrhage in ten questions

Traumatic subarachnoid hemorrhage (SAH) has an annual incidence of 9 per 100 000 people. It is a rare but serious event, with an estimated mortality rate of 40% within the first 48hours. In 85% of cases, it is due to rupture of an intracranial aneurysm. In the early phase, during the first 24hours, cerebral CT, combined with intracranial CT angiography is recommended to make a positive diagnosis of SAH, to identify the cause and to investigate for an intracranial aneurysm. Cerebral MRI may be proposed if the patient's clinical condition allows it. FLAIR imaging is more sensitive than CT to demonstrate a subarachnoid hemorrhage and offers greater degrees of sensitivity for the diagnosis of restricted subarachnoid hemorrhage in cortical sulcus. A lumbar puncture should be performed if these investigations are normal while clinical suspicion is high.

The active extravasation of contrast (spot sign) depicted on multidetector computed tomography angiography might predict structural vascular etiology and mortality in secondary intracranial hemorrhage

OBJECTIVE

Intracerebral hemorrhage (ICH) occurs in 10% to 15% of all strokes and is accompanied by high rates of mortality, disability, and neurological sequelae. Our aim was to assess the presence and prognostic implications of the active extravasation of contrast within the hemorrhage (spot sign) in a series of patients with secondary ICH.

METHODS

We analysed 59 subjects who arrived at a tertiary hospital with secondary ICH and a brain parenchyma hemorrhage greater than 2.0 cm in any axis.

RESULTS

Spot sign was observed in 11 subjects, including 8 patients with saccular aneurysm, 1 with arteriovenous malformation, 1 with coagulation disorder and 1 with venous sinus thrombosis. A 37.5% mortality rate was documented in the spot sign-negative group, whereas the presence of this imaging finding was followed by an 81.8% in-hospital mortality rate.

CONCLUSIONS

Spot sign was correlated with vascular etiology and was a predictor of mortality in our series of patients.

The Impact of Transient Hepatic Attenuation Differences in the Diagnosis of Pseudoaneurysm and Arteriovenous Fistula on Follow-Up CT Scans after Blunt Liver Trauma

A feared complication to liver trauma is delayed vascular complication, such as pseudoaneurysm and arteriovenous fistula (PS/AF) seen as focal enhancement on contrast-enhanced computed tomography (CT) in the arterial phase. A hyperdense area termed transient hepatic attenuation difference (THAD) representing altered hepatic blood flow can be seen in the arterial phase near the liver lesion. The objective of this study was to describe THAD and PS/AF on follow-up CT after blunt liver trauma, and to evaluate if THAD influenced the evaluation of PS/AF. Three radiology residents retrospectively evaluated scans of 78 patients. The gold standard for PS/AF was an evaluation by an experienced senior radiologist, while THAD was a consensus between the residents. PS/AF was present in 14% and THAD in 54%. THAD was located in the periphery of the lesion with hazy borders and mean HU levels of 100, while PS/AF was located within the lesion with focal enhancement and mean HU levels of 170 (p < 0.05). In evaluation of PS/AF, the likelihood of agreement between the observers and the gold standard was 89% when THAD was present, and 98% when THAD was absent (p = 0.04). THAD is common and can hamper the evaluation of PS/AF.

64-section multidetector CT angiography for evaluation of intracranial aneurysms: comparison with 3D rotational angiography

BACKGROUND

To assess the diagnostic performance of 64-section computed tomography angiography (CTA) for detection of cerebral aneurysms by comparison with the new gold standard three-dimensional (3D) digital subtraction angiography (DSA).

MATERIAL AND METHODS

A total of 128 patients who underwent both 64-section CTA and 3D DSA for suspected intracranial aneurysms were included. The location, size, and shape of the aneurysm were assessed and compared with 3D DSA results. The sensitivity, specificity, positive and negative predictive values of 64-section CTA were calculated by using 3D DSA as reference standard.

RESULTS

According to the reference standard, a total of 145 aneurysms were detected at 3D DSA in 118 patients. Of these 145 aneurysms, 64-section CTA detected 139 aneurysms in 118 patients. The sensitivity of CTA for detection of aneurysm was 95.8% on a per-aneurysm basis. All missed aneurysms were non-causative very small aneurysms in patients harboring multiple aneurysms. On a per-patient basis, the sensitivity, specificity, positive and negative predictive values were 100%.

CONCLUSION

Compared with the new gold standard 3D DSA, 64-section CTA offers high sensitivity and specificity for detection of intracranial aneurysms. It could be readily used as a screening imaging method for detection of intracranial aneurysms.

Evaluating of small intracranial aneurysms by 64-detector CT Angiography: a comparison with 3-dimensional rotation DSA or surgical findings

BACKGROUND AND PURPOSE

The diagnostic performance of 64-detector computed tomographic angiography (CTA) for detection of small intracranial aneurysms (SIAs) was evaluated.

METHODS

In this prospective study, 112 consecutive patients underwent 64-detector CTA before volume-rendering rotation digital subtraction angiography (VR-RDSA) or surgery. VR-RDSA or intraoperative findings or both were used as the gold standards. The accuracy, sensitivity, specificity, and positive predictive values (PPV) and negative predictive values (NPV), as measures to detect or rule out SIAs, were determined by patient-based and aneurysm size-based evaluations.

RESULTS

The reference standard methods revealed 84 small aneurysms in 71 patients. The results of patient-based 64-detector CTA evaluation for SIAs were: accuracy, 98.2%; sensitivity, 98.6%; specificity, 97.6%; PPV, 98.6%; and NPV, 97.6%. The aneurysm-based evaluation results were: accuracy, 96.8%; sensitivity, 97.6%; specificity, 95.1%; PPV, 97.6%; and NPV, 95.1%. Two false-positive and two false-negative findings for aneurysms <3 mm in size occurred in the 64-detector CTA analysis.

CONCLUSION

The diagnostic performance of 64-detector CTA did not improve much compared with 16-detector CTA for detecting SIAs, especially for very small aneurysms. VR-RDSA is still necessary for patients with a history of subarachnoid hemorrhage if the CTA findings are negative.

320-detector row CT angiography for detection and evaluation of intracranial aneurysms: comparison with conventional digital subtraction angiography

AIM

To compare the diagnostic performance of 320-detector row computed tomographic angiography (CTA) with digital subtraction angiography (DSA) for the detection and characterization of intracranial aneurysms.

MATERIALS AND METHODS

Fifty-two consecutive patients with non-traumatic subarachnoid haemorrhage (SAH) and suspected intracranial aneurysms were evaluated from January 2009 to October 2011. All underwent both 320-detector row volume CTA examination and DSA. CTA volume data were transmitted to a VITREA workstation and two physicians with experience in diagnostic imaging of the nervous system independently carried out image post-processing and assessed the results. The three-dimensional (3D) CTA and DSA images were assessed using intraoperative findings as the reference standard.

RESULTS

In 52 patients, 54 aneurysms were detected; 48 patients underwent surgery for 50 aneurysms. The overall sensitivity, specificity, and accuracy of 3D CTA were 96.3, 100, and 94.6%, respectively. Meanwhile, the overall sensitivity, specificity, and accuracy of DSA were 98.1, 98.1, and 95.1%, respectively. For aneurysms less than 3 mm, the sensitivity, specificity, and accuracy of 3D CTA were 81.8, 100, and 93.3%, respectively. The sensitivity, specificity, and accuracy of DSA for small aneurysms were 90.9, 100, and 96.2%, respectively. 3D CTA was superior to DSA in demonstrating aneurysmal calcification, parent artery, and surrounding vascular anatomy.

CONCLUSIONS

3D CTA is a highly sensitive, specific, and non-invasive imaging method for diagnosis and evaluation of intracranial aneurysms. It also allows for precise depiction of aneurysm morphology. Therefore, 320-detector row CTA may be used as an alternative to DSA as a first-line imaging technique in patients with SAH.

Nontraumatic subarachnoid hemorrhage management: evaluation with reduced iodine volume at CT angiography

PURPOSE

To evaluate the technical quality and the diagnostic performance of a protocol with use of low volumes of contrast medium (25 mL) at 64-detector spiral computed tomography (CT) in the diagnosis and management of adult, nontraumatic subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

This study was performed outside the United States and was approved by the institutional review board. Intracranial CT angiography was performed in 73 consecutive patients with nontraumatic SAH diagnosed at nonenhanced CT. Image quality was evaluated by two observers using two criteria: degree of arterial enhancement and venous contamination. The two independent readers evaluated diagnostic performance (lesion detection and correct therapeutic decision-making process) by using rotational angiographic findings as the standard of reference. Sensitivity, specificity, and positive and negative predictive values were calculated for patients who underwent CT angiography and three-dimensional rotational angiography. The intraclass correlation coefficient was calculated to assess interobserver concordance concerning aneurysm measurements and therapeutic management.

RESULTS

All aneurysms were detected, either ruptured or unruptured. Arterial opacification was excellent in 62 cases (85%), and venous contamination was absent or minor in 61 cases (84%). In 95% of cases, CT angiographic findings allowed optimal therapeutic management. The intraclass correlation coefficient ranged between 0.93 and 0.95, indicating excellent interobserver agreement.

CONCLUSION

With only 25 mL of iodinated contrast medium focused on the arterial phase, 64-detector CT angiography allowed satisfactory diagnostic and therapeutic management of nontraumatic SAH.

Cerebral CT angiography using a small volume of concentrated contrast material with a test injection method: optimal scan delay for quantitative and qualitative performance

OBJECTIVES

The objective of this study was to determine the optimal scan delay quantitatively and qualitatively in cerebral CT angiography (CTA) with a test injection method at the circle of Willis (cW).

METHODS

66 consecutive patients suspected of having unruptured intracranial aneurysms underwent CTA using 40 ml of 370 mg iodine ml(-1) contrast material (CM). After the time until CM arrival at the cW (T(cW)) was calculated, scan delay was divided into three groups according to T(cW) and scan duration (SD) between the second cervical vertebra and cW as follows: [(T(cW)+6)-SD] in 21 patients (Group A); [(T(cW)+8)-SD] in 23 patients (Group B); and [(T(cW)+10)-SD] in 22 patients (Group C). Arterial and venous attenuation in the intracranial vessels was measured. Mean attenuation values were compared quantitatively. The arterial enhancement and venous overlap at the cW and above the cW were qualitatively compared among the three groups.

RESULTS

Mean arterial attenuation in Groups B and C was significantly higher than that in Group A. Mean venous attenuation in Group C was significantly higher than those in Groups A and B. Arterial enhancement above the cW showed a significant difference between Groups A and C, and at the cW between Groups A and B, and Groups A and C. There was a significant difference in venous overlap among the three groups, except for that at the cW between Groups B and C.

CONCLUSIONS

Setting scan delay as [(T(cW)+8)-SD] s can produce the best performance both quantitatively and qualitatively.

Comparison of standard- and low-tube voltage 320-detector row volume CT angiography in detection of intracranial aneurysms with digital subtraction angiography as gold standard

RATIONALE AND OBJECTIVES

The aim of this study was to prospectively assess the effect of low-tube voltage (80 kVp) 320-detector row volume computed tomographic (CT) angiography (L-VCTA) in the detection of intracranial aneurysms, with three-dimensional (3D) spin digital subtraction angiography (DSA) as the gold standard.

MATERIALS AND METHODS

Forty-eight patients with clinically suspected subarachnoid hemorrhages were divided into two groups. One group underwent L-VCTA and DSA, while the other group underwent conventional-tube voltage (120 kVp) volume CT angiography (C-VCTA) and DSA. Vascular enhancement, image quality, detection accuracy of aneurysms, and radiation dose were compared between the two groups.

RESULTS

For objective image quality, the L-VCTA group had higher mean vessel attenuation, correlated with higher image noise and lower signal-to-noise ratio, than the C-VCTA group. For subjective image quality, there were no significant differences between the two groups regarding scores for arterial enhancement, depiction of small arterial detail, interference of venous structures, and overall image quality scores. The mean effective dose for the L-VCTA group was significantly lower than for the C-VCTA group (0.56 ± 0.25 vs 1.84 ± 0.002 mSv), with a reduction of radiation dose of 69.73%. With 3D DSA as the reference standard, the sensitivity, specificity, and accuracy in the L-VCTA and C-VCTA groups were 94.12%, 100%, 94.4% and 100%, 100%, and 100%, respectively. In both groups, there were significant correlations for maximum aneurysm diameter measurements between volume CT angiography and 3D DSA; no statistical difference in the mean maximum diameter of each aneurysm was measured between volume CT angiography and 3D DSA.

CONCLUSIONS

L-VCTA is helpful in detecting intracranial aneurysms, with results similar to those of 3D DSA, but at a lower radiation dose than C-VCTA.

The Role of 3 Tesla MRA in the Detection of Intracranial Aneurysms

Intracranial aneurysms constitute a common pathological entity, affecting approximately 1–8% of the general population. Their early detection is essential for their prompt treatment. Digital subtraction angiography is considered the imaging method of choice. However, other noninvasive methodologies such as CTA and MRA have been employed in the investigation of patients with suspected aneurysms. MRA is a noninvasive angiographic modality requiring no radiation exposure. However, its sensitivity and diagnostic accuracy were initially inadequate. Several MRA techniques have been developed for overcoming all these drawbacks and for improving its sensitivity. 3D TOF MRA and contrast-enhanced MRA are the most commonly employed techniques. The introduction of 3 T magnetic field further increased MRA's sensitivity, allowing detection of aneurysms smaller than 3 mm. The development of newer MRA techniques may provide valuable information regarding the flow characteristics of an aneurysm. Meticulous knowledge of MRA's limitations and pitfalls is of paramount importance for avoiding any erroneous interpretation of its findings.

Sixty-four-row multislice computed tomographic angiography in the diagnosis and characterization of intracranial aneurysms: comparison with 3D rotational angiography

BACKGROUND

Sixty-four-row multislice computed tomographic angiography (CTA) has great potential for use in vascular studies. The aim of our study was to compare 64-slice CTA with three-dimensional rotational angiography (3DRA) in the detection and characterization of intracranial aneurysms with special attention to smaller (<3-mm) aneurysms.

METHODS

In a prospective study, a total of 133 patients were included who successively underwent 64-slice CTA and digital subtraction angiography (DSA) examinations for suspected intracranial aneurysms. The 64-slice CTA, conventional DSA, and 3DRA images were independently reviewed by five readers who performed the presence, shape, dimension, and location of aneurysms. The 3DRA results were considered as the ultimate reference standard.

RESULTS

The reference standard revealed 111 aneurysms in 93 patients: 27 aneurysms were read as <3 mm, 66 were read as being between 3 and 8 mm, and 18 were read as >8 mm. The sensitivities of 64-slice CTA for aneurysms<3 mm, between 3 and 8 mm, and >8 mm were 96.3%, 98.5%, and 100%, respectively, on a per-aneurysm basis. The sensitivities of conventional DSA for aneurysms<3 mm, between 3 and 8 mm, and >8 mm were 85.2%, 100%, and 100%, respectively, on a per-aneurysm basis. The 64-slice CT angiographic images could clearly show the aneurysmal characteristics and the relationship between aneurysms and adjacent branch vessels.

CONCLUSION

Sixty-four-slice CTA is a highly accurate imaging examination of the first-line imaging technique for detecting and characterizing intracranial aneurysms including <3-mm aneurysms.

Automatic bone removal dual-energy CT angiography for the evaluation of intracranial aneurysms

PURPOSE

To evaluate the diagnostic accuracy of dual-energy computed tomographic angiography (DE-CTA) in the detection of intracranial aneurysms and to determine whether DE-CTA provides adequate information to guide treatment choice.

MATERIALS AND METHODS

Eighty patients (31 men and 49 women; mean [SD] ages of 52 [9] years) with spontaneous subarachnoid hemorrhage underwent DE-CTA. The performance of DE-CTA was compared with conventional CTA created from average weighted images and digital subtraction angiography (DSA). Sensitivity and specificity for aneurysm detection were determined on a per-patient and per-aneurysm basis. The treatment choice was assessed on the basis of aneurysm neck size and/or the dome/neck ratio.

RESULTS

With DSA as reference standard (n = 61; 47 aneurysms in 41 patients), DE-CTA correctly detected 45 aneurysms in 41 patients corresponding to sensitivity and specificity of 100% and 95.0% on a per-patient basis versus 95.7% and 95.0% on a per-aneurysm basis, whereas conventional CTA correctly detected 43 aneurysms in 39 patients corresponding to sensitivity and specificity of 95.1% and 95.0% on a per-patient basis versus 91.5% and 95.0% on a per-aneurysm basis. No statistical difference between DE-CTA and conventional CTA was found for the diagnostic evaluation of intracranial aneurysms. Surgery was performed to treat 38 aneurysms, coiling in 26 aneurysms, stent in one patient, and follow-up in the remaining 5 aneurysms. Dual-energy CTA correctly predicted treatment choice in 44 aneurysms, with 15 aneurysms coiled and 29 aneurysms clipped.

CONCLUSIONS

Compared with DSA, DE-CTA had a comparable diagnostic accuracy for the detection of intracranial aneurysms, visualization of the morphology of aneurysms at the skull base, and prediction of aneurysm treatment choice in most patients with spontaneous subarachnoid hemorrhage based on this study.

Value of noninvasive imaging in follow-up of intracranial aneurysm

Follow-up is necessary for treated and untreated aneurysms. The purpose of this study is to assess the results of treated aneurysms, the development of untreated aneurysms and the incidence of new aneurysms through short-term follow-up with noninvasive imaging, including CTA and MRA. More-than-once follow-up imaging with either CTA or MRA was performed in 73 patients, 65 of them suffering SAH. CTA was performed in 46 patients with clipped aneurysms, 9 patients with coiled aneurysms and 8 cases with untreated aneurysms. MRA was performed in ten patients with coiled aneurysms. CTA follow-up demonstrated that in 48 clipped aneurysms, 47 aneurysms completely disappeared; one aneurysm with neck remnant and one new aneurysm was found. No recurrence was found after microsurgical clipping. CTA follow-up provided limited information for ten coiled aneurysms because of poor quality images due to artifacts from coil. MRA follow-up of 12 coiled aneurysms showed there were no recanalization, recurrence or new aneurysm. In 20 untreated aneurysms, 19 stayed unchanged, and one aneurysm automatically disappeared. The newest generation of CTA and MRA can be used for following-up of intracranial aneurysms, and is more readily accepted by Chinese patients because of convenience, non-invasiveness and low price.

Detection and Characterization of Intracranial Aneurysms with Dual-Energy Subtraction CTA: Comparison with DSA

BACKGROUND

to investigate the diagnostic performance of dual-energy subtraction CTA in evaluating intracranial aneurysms by comparison with DSA.

METHODS

ninety-seven patients with suspected intracranial aneurysms were included into our study and completed both 64-section dual-energy subtraction CTA and DSA examinations. Two independent readers retrospectively reviewed all subtraction CTA images in a blinded manner. Sensitivity, specificity, positive predictive value and negative predictive value of subtraction CTA and DSA were calculated on a per-patient and per-aneurysm basis.

RESULTS

according to the reference standard, 96 aneurysms were present in 81 patients and no aneurysm was found in 16 patients. The overall sensitivity, specificity, positive predictive value and negative predictive value of subtraction CTA on a per-aneurysm basis were 98.9, 100, 100 and 94.1%, respectively. DSA prospectively detected 88 aneurysms in 79 of 81 patients. On a per-aneurysm basis, the sensitivity, specificity, positive predictive value and negative predictive value of DSA were 91.7, 100, 100 and 66.7%, respectively.

CONCLUSION

the diagnostic accuracy of 64-section dual-energy subtraction CTA is promising in detection and characterization of intracranial aneurysms. In most cases, it may substitute for conventional DSA as the primary imaging method in the diagnostic work-up of intracranial aneurysms.

Advanced imaging applications for endovascular procedures

Advanced imaging techniques, particularly in CT and MRI, have become state-of-the-art to support the performance of interventional neuroradiologic procedures. Multidetector CT scanners with submillimeter detectors and real-time workstations have allowed the use of a noninvasive study, CT angiography, as a first-line diagnostic study at many institutions to detect and evaluate the morphology of aneurysms. Follow-up for postsubarachnoid spasm now includes transcranial Doppler, CT angiography, and sometimes perfusion to guide therapy. While both intracranial and extracranial stenosis have long been well evaluated by MR and CT angiography, information about the intimal wall and plaque morphology is now possible. In the setting of acute ischemia, CT with perfusion or MR with diffusion and perfusion has increased the ability to separate territory at risk from infarcted tissue, and can help to guide more appropriate intervention. This article addresses current state-of the-art imaging applications as well as a few techniques on the horizon that show great promise in helping to characterize those lesions amenable to endovascular therapy.

Diagnosis of unruptured intracranial aneurysms: 3T MR angiography versus 64-channel multi-detector row CT angiography

BACKGROUND AND PURPOSE

We compared 3-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) using a 3-tesla (T) MR unit with 64-channel multi-detector row computed tomographic angiography (64-MDCTA) for detection and characterization of angiographically proven unruptured intracranial aneurysms.

METHODS

Thirty-eight patients with 47 aneurysms and 8 patients without aneurysms underwent 3T, 3D TOF MRA; 64-MDCTA; and intra-arterial angiography. As a first study, 3 radiologists blinded to pertinent clinical information independently reviewed MRA and CTA images. We evaluated diagnostic accuracy using an alternative free-response receiver operating characteristic (AFROC) analysis and evaluated the sensitivity and specificity of each technique. Next, 2 radiologists used volume-rendering images generated from MRA or CTA data to evaluate the morphology of the 47 aneurysms detected, and MRA and CTA results were compared. Three-dimensional digital angiography (DA) images were used as the standard of reference.

RESULTS

On the AFROC analysis, the value of the mean area under the AFROC curve (A(1)) was 0.91 for both modalities. Mean sensitivity of 89% and specificity of 76% for MRA were not significantly different from sensitivity of 87% and specificity of 79% for CTA. Therefore, when used to evaluate aneurysmal morphology, both modalities appear satisfactory for determining these vascular anomalies.

CONCLUSION

Three-tesla, 3D TOF MRA and 64-MDCTA are excellent modalities with high diagnostic accuracy for evaluating unruptured intracranial aneurysms and no significant difference between them in diagnostic performance.

Infected (mycotic) aneurysms: spectrum of imaging appearances and management

Infected aneurysms are uncommon. The aorta, peripheral arteries, cerebral arteries, and visceral arteries are involved in descending order of frequency. Staphylococcus and Streptococcus species are the most common causative pathogens. Early clinical diagnosis of infected aneurysms is challenging owing to their protean manifestations. Clinically apparent infected aneurysms are often at an advanced stage of development or are associated with complications, such as rupture. Nontreatment or delayed treatment of infected aneurysms often has a poor outcome, with high morbidity and mortality from fulminant sepsis or hemorrhage. Current state-of-the-art imaging modalities, such as multidetector computed tomography and magnetic resonance imaging, have replaced conventional angiography as minimally invasive techniques for detection of infected aneurysms in clinically suspected cases, as well as characterization of infected aneurysms and vascular mapping for treatment planning in confirmed cases. Doppler ultrasonography allows noninvasive assessment for infected aneurysms in the peripheral arteries. Imaging features of infected aneurysms include a lobulated vascular mass, an indistinct irregular arterial wall, perianeurysmal edema, and a perianeurysmal soft-tissue mass. Perianeurysmal gas, aneurysmal thrombosis, aneurysmal wall calcification, and disrupted arterial calcification at the site of the infected aneurysm are uncommon findings. Imaging-guided endovascular stent-graft repair and embolotherapy can be performed in select cases instead of open surgery. Familiarity with the imaging appearances of infected aneurysms should alert the radiologist to the diagnosis and permit timely treatment, which may include endovascular techniques.

Detection of aneurysms by 64-section multidetector CT angiography in patients acutely suspected of having an intracranial aneurysm and comparison with digital subtraction and 3D rotational angiography

BACKGROUND AND PURPOSE

Four-section multisection CT angiography (MSCTA) accurately detects aneurysms at or more than 4 mm but is less accurate for those less than 4 mm. Our purpose was to determine the accuracy of 64-section MSCTA (64MSCTA) in aneurysm detection versus combined digital subtraction angiography (DSA) and 3D rotational angiography (3DRA).

MATERIALS AND METHODS

In a retrospective review of patients studied because of acute symptoms suspicious for arising from an intracranial aneurysm, 63 subjects were included who had undergone CT angiography (CTA). Of these, 36 underwent catheter DSA; all but 4 were also studied with 3DRA. The most common indication was subarachnoid hemorrhage (SAH; n = 43). Two neuroradiologists independently reviewed each CTA, DSA, and 3DRA.

RESULTS

A total of 41 aneurysms were found in 28 patients. The mean size was 6.09 mm on DSA/3DRA and 5.98 mm on 64MSCTA. kappa was excellent (0.97) between the aneurysm size on 64MSCTA and DSA/3DRA. Ultimately, 37 aneurysms were detected by DSA/3DRA in 25 of the 36 patients who underwent conventional angiography. The reviewers noted four 1- to 1.5-mm sessile outpouchings only on 3DRA; none were considered a source of SAH. One 64MSCTA was false positive, whereas one 2-mm aneurysm was missed by CTA. The sensitivity of CTA for aneurysms less than 4 mm was 92.3%, whereas it was 100% for those 4-10 mm and more than 10 mm, excluding the indeterminate, sessile lesions.

CONCLUSIONS

In comparison with the available literature, 64MSCTA may have improved the detection of less than 4-mm aneurysms compared with 4- or 16-section CTA. However, the combination of DSA with 3DRA is currently the most sensitive technique to detect untreated aneurysms and should be considered in suspicious cases of SAH where the aneurysm is not depicted by 64MSCTA, because 64MSCTA may occasionally miss aneurysms less than 3-4 mm size.