Can CT angiography reconstructed from CT perfusion source data on a 320-section volume CT scanner replace conventional CT angiography for the evaluation of intracranial arteries?

3D reconstructions, 4D imaging and postprocessing with CT in musculoskeletal disorders: Past, present and future

Three-dimensional (3D) imaging and post processing are common tasks used daily in many disciplines. The purpose of this article is to review the new postprocessing tools available. Although 3D imaging can be applied to all anatomical regions and used with all imaging techniques, its most varied and relevant applications are found with computed tomography (CT) data in musculoskeletal imaging. These new applications include global illumination rendering (GIR), unfolded rib reformations, subtracted CT angiography for bone analysis, dynamic studies, temporal subtraction and image fusion. In all of these tasks, registration and segmentation are two basic processes that affect the quality of the results. GIR simulates the complete interaction of photons with the scanned object, providing photorealistic volume rendering. Reformations to unfold the rib cage allow more accurate and faster diagnosis of rib lesions. Dynamic CT can be applied to cinematic joint evaluations a well as to perfusion and angiographic studies. Finally, more traditional techniques, such as minimum intensity projection, might find new applications for bone evaluation with the advent of ultra-high-resolution CT scanners. These tools can be used synergistically to provide morphologic, topographic and functional information and increase the versatility of CT.

Four-dimensional CT angiography (4D-CTA) in the evaluation of juvenile nasopharyngeal angiofibromas: comparison with digital subtraction angiography (DSA) and surgical findings

OBJECTIVES

To explore the value of four-dimensional CT angiography (4D-CTA) in the preoperative evaluation of juvenile nasopharyngeal angiofibromas (JNAs) using 320-row volume CT.

METHODS

4D-CTA and DSA data of 18 patients with histopathologically proven JNAs were retrospectively reviewed. The location, extent, feeding vessels and stage of JNAs were assessed by two radiologists independently and blindly. The agreements between both reviewers and between 4D-CTA and surgical findings for assessing the above indicators were analysed, respectively. The radiation dose and the number of feeding arteries between 4D-CTA and digital subtraction angiography (DSA) were also compared.

RESULTS

4D-CTA showed high diagnostic consistency with surgical pathology for JNAs with consistent rates of 96.2 and 100% in both reviewers, respectively. The effective dose of 4D-CTA was significantly less than that of DSA (p < 0.001). Good agreements between 4D-CTA and surgical findings and between the two reviewers were found in the assessment of the location, extent and stage of JNAs. 4D-CTA showed that 15 lesions were supplied strictly by the external carotid artery circulation and 3 by the external and internal carotid artery supply, which was in accordance with DSA. There were no significant differences in the main arterial feeder number obtained by 4D-CTA and DSA between different observers (all p > 0.05).

CONCLUSIONS

4D-CTA can provide a reliable preoperative diagnosis and assessment of JNAs, which is useful for determining the surgical strategy and management of this condition.

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.

Additive value of 320-section low-dose dynamic volume CT in relation to 3-T MRI for the preoperative evaluation of brain tumors

PURPOSE

To assess whether 320-section low-dose dynamic volume computed tomography (320-LDVCT) with adaptive iterative dose reduction (AIDR) adds value to 3-T MRI for the preoperative evaluation of brain tumors.

METHODS

The study population was comprised of 16 consecutive patients with brain tumors who, in addition to preoperative 3-T MRI, underwent 320-LDVCT with AIDR. Two radiologists independently evaluated the CT and MRI studies; one measured the relative cerebral blood volume (rCBV) in the tumor and contralateral brain on CT and MR perfusion maps. Interobserver agreement was assessed by κ statistics.

RESULTS

In 3 of 16 patients (19 %), 320-LDVCT added diagnostic value to 3-T MRI studies with respect to the visualization of feeders (κ = 0.77), and in 12 (75 %) it helped the delineation of venous structures (κ = 0.71) and the relationship between the tumor and adjacent vessels (κ = 0.85). The average standardized rCBV value was 12.2 ± 2.40 (range 0.7-36.6) on MR and 8.80 ± 2.77 (range 0.8-38.0) on CT perfusion studies; the correlation between these values was very strong (r = 0.92, p < 0.0001). According to the neurosurgeons, 320-LDVCT added helpful information for surgery in 4 patients (25 %).

CONCLUSION

The 320-LDVCT can add value to 3-T MRI for the tumor feeders and relationship between the tumor and adjacent vessels.

Reduction of misregistration on cerebral four-dimensional computed tomography angiography images using advanced patient motion correction reconstruction

PURPOSE

The aim of this study was to evaluate whether advanced patient motion correction (APMC) can reduce the misregistration of pixels between the different X-ray tube positions in four-dimensional CT angiography (4D-CTA).

MATERIALS AND METHODS

Eight patients with intracranial aneurysms were included in this retrospective study. We compared the CTA images with APMC reconstruction and half-scan reconstruction with regard to the following 3 items: (1) bone misalignment area; (2) image noise; and (3) aneurysm volume change.

RESULTS

The bone misalignment area and image noise were significantly reduced in the APMC images, as compared to that in the half-scan reconstruction images (bone misalignment area: 33.0 ± 18.1 cm(3) vs 152.0 ± 72.2 cm(3), respectively; p < 0.001) (image noise at pons: 9.70 ± 2.58 vs 15.16 ± 5.02, respectively, p < 0.001). The aneurysm volume and volume variance were significantly smaller in the APMC reconstruction than those in the half-scan reconstruction (volume: 1107.2 ± 1813.8 mm(3) vs 1135.1 ± 1853.8 mm(3); p < 0.05; coefficient of variation: 0.0291 ± 0.014 vs 0.0463 ± 0.026, p < 0.05, respectively).

CONCLUSION

Our results show that APMC reduces the reconstruction related misregistration between the cardiac phases compared to half-scan reconstruction.

Diagnosis and Treatment of Intracranial Aneurysms with 320-Detector Row Volumetric Computed Tomography Angiography

OBJECTIVES

The objective of the study was to determine the clinical utility of 320-detector row volume-computed tomographic angiography (VCTA) in the management of intracranial aneurysms.

METHODS

Between February 2011 and May 2015, 550 patients successfully underwent 320-detector row VCTA for suspected intracranial aneurysms. Three-dimensional (3D) digital subtraction angiography (DSA) was used as the ultimate reference standard, and the sensitivity, specificity, and accuracy of both nonsubtracted and subtracted VCTA in identifying aneurysms were analyzed.

RESULTS

Nonsubtracted VCTA identified 417 aneurysms (2 false-positive readings, 12 false-negative readings). The diagnostic sensitivity, specificity, and accuracy of non-subtracted VCTA, on a per-aneurysm basis, were 97.2%, 99.0%, and 97.6%, respectively. Subtracted VCTA identified 426 aneurysms (2 false-positive readings, 3 false-negative readings). The sensitivity, specificity, and accuracy of subtracted VCTA, on a per-aneurysm basis, were 99.3%, 99.0%, and 99.2%, respectively. No differences in diagnostic accuracy were found between subtracted VCTA and 3D DSA. Nonsubtracted VCTA, however, was observed to be significantly less sensitive than 3D DSA and subtracted VCTA. Twenty-six aneurysm cases were referred for surgical treatment based on VCTA imaging. All aneurysms were deemed completely occluded during surgical clipping. On the basis of VCTA imaging, 299 aneurysms were found suitable for endovascular coiling, of which 293 aneurysms (98%) were treated successfully.

CONCLUSIONS

The 320-detector row subtracted VCTA technique is an effective, first-line diagnostic imaging modality for surgical and endovascular treatment of aneurysms. The nonsubtracted VCTA was less accurate than the subtracted VCTA, especially for intracranial aneurysms adjoining bone tissue.