Whole-brain CT digital subtraction angiography of cerebral dural arteriovenous fistula using 320-detector row CT

Urodynamic 4D-CT evaluation: 320-row area detector CT scanner combined with PhyZiodynamics software analysis provides an innovative system to evaluate urinary flow and outlet obstructions

Background

Evaluation of the morphology of the lower urinary tract as well as the movements associated with urination are required for the symptomatic diagnosis of lower urinary tract obstruction as well as the assessment of postoperative adaptation. However, no tool currently exists for direct and easy patient evaluation.

Purpose

To evaluate lower urinary tract obstruction and postoperative adaptation using a four-dimensional (4D) virtual reality urination image (urodynamic 4D-CT image).

Material and Methods

We used a 320-row area detector CT scanner and PhyZiodynamics image analysis software to perform 197 urodynamic 4D-CT examinations on 175 first-time patients between January 2014 and March 2017.

Results

A comparison of the obtained images before and after holmium laser enucleation of the prostate revealed the morphological changes due to prostate enucleation and enabled visualization of the ideal urination conditions, showing that the anatomical structural changes during urination and the opening of the urethra play a major role in improving voiding function.

Conclusion

Using low-dosage radiation, the sharply defined moving image obtained via urodynamic 4D-CT examination can be utilized as a physiological diagnostic tool to evaluate a series of urinary movements from any angle between the prostate, urethra, and bladder in a unitary manner with the time axis added. There was negligible patient impact. This technique could provide new opportunities for the diagnosis of lower urinary tract symptoms and post-surgical adaptation assessment.

Clinical applications of dynamic CT angiography for intracranial lesions

BACKGROUND

Dynamic CT angiography (dCTA) augments traditional CTA with temporal resolution and has been demonstrated to influence operative planning in skull base surgery.

METHODS

Three hundred twenty-five dynamic CTA cases from a single institution were reviewed for indication of study, findings, and comparison to other modalities of imaging.

RESULTS

The most frequent application of dCTA was pre-operative surgical planning (59.4%); resection of skull base tumors represented the majority of these pre-operative studies (93.3%). It was also used to evaluate new neurological symptoms (20.9%). Of these, the most common symptoms prompting a dCTA study included headache (22.1%) and visual field deficit (11.8%). The most commonly visualized vascular lesions were partial (22.9%) and complete vascular occlusions (9.0%). Dynamic CTA has also been useful in post-operative imaging for vascular malformations (9.5%) and tumors (2.5%). Finally, dCTA was employed to evaluate ambiguous abnormal findings observed on other imaging modalities (7.7%). Cerebral dCTA ruled out inconclusive abnormal vascular findings visualized on other imaging modalities (64.0%) more frequently than it confirmed them (32.0%), and was inconclusive in a singular case (4.0%).

CONCLUSIONS

Cerebral dCTA is an evolving new technology with a diverse spectrum of potential applications. In addition to its role in guiding pre-operative planning for skull base surgical cases, dynamic CTA offers excellent spatial and temporal resolution for assessment of vascular lesions.

Pulsatile Tinnitus: Differential Diagnosis and Radiological Work-Up

PURPOSE OF REVIEW

Identification of the underlying cause of pulsatile tinnitus is important for treatment decision making and for prognosis estimation. For this, an adequate diagnostic imaging strategy is crucial.

RECENT FINDINGS

Both CT and MRI can be useful, and in general, these modalities provide complementary diagnostic information. The scanning protocol can be optimized based on the estimated a priori chance for finding specific pathology, or the need to rule out more rare but clinical significant disease. In recent years, dynamic CTA, also referred to as 4D-CTA, has become available as a new technique that enables non-invasive evaluation of hemodynamics for the detection, classification, and follow-up of vascular malformations.

SUMMARY

The value of different diagnostic imaging modalities in the work-up of pulsatile tinnitus is discussed in relation to the differential diagnosis. Furthermore, imaging findings of different diseases are presented, both for CT and MRI.

Xenon-enhanced CT using subtraction CT: Basic and preliminary clinical studies for comparison of its efficacy with that of dual-energy CT and ventilation SPECT/CT to assess regional ventilation and pulmonary functional loss in smokers

PURPOSE

To prospectively and directly compare the capability for assessments of regional ventilation and pulmonary functional loss in smokers of xenon-ventilation CT obtained with the dual-energy CT (DE-CT) and subtraction CT (Sub-CT) MATERIALS AND METHODS: Twenty-three consecutive smokers (15 men and 8 women, mean age: 69.7±8.7years) underwent prospective unenhanced and xenon-enhanced CTs, the latter by Sub-CT and DE-CT methods, ventilation SPECT and pulmonary function tests. Sub-CT was generated from unenhanced and xenon-enhanced CT, and all co-registered SPECT/CT data were produced from SPECT and unenhanced CT data. For each method, regional ventilation was assessed by using a 11-point scoring system on a per-lobe basis. To determine the functional lung volume by each method, it was also calculated for individual sublets with a previously reported method. To determine inter-observer agreement for each method, ventilation defect assessment was evaluated by using the χ2 test with weighted kappa statistics. For evaluation of the efficacy of each method for pulmonary functional loss assessment, functional lung volume was correlated with%FEV₁.

RESULTS

Each inter-observer agreement was rated as substantial (Sub-CT: κ=0.69, p<0.0001; DE-CT: κ=0.64, p<0.0001; SPECT/CT: κ=0.64, p<0.0001). Functional lung volume for each method showed significant to good correlation with%FEV₁ (Sub-CT: r=0.72, p=0.0001; DE-CT: r=0.74, p<0.0001; SPECT/CT: r=0.66, p=0.0006).

CONCLUSION

Xenon-enhanced CT obtained by Sub-CT can be considered at least as efficacious as that obtained by DE-CT and SPECT/CT for assessment of ventilation abnormality and pulmonary functional loss in smokers.

Radiation Dose Reduction in 4D Cerebral CT Angiography by Individualized Estimation of Cerebral Circulation Time

BACKGROUND AND PURPOSE

The novel technique of 4D CTA for dynamic assessment of the intracranial vessels has a greater radiation burden than conventional CTA. Previous descriptions of the technique used a fixed-duration exposure protocol. This study examines the potential for dose reduction by individualizing exposure time to patient physiology by the use of time-enhancement curve techniques as previously applied in CT angiography and venography.

MATERIALS AND METHODS

4D-CTA examinations performed at our institution were retrospectively reviewed. Scan protocols used a test-bolus scan with either a subjective estimate of the main acquisition timing (estimated-duration method) or a quantitative measure (measured-duration method). The estimated-duration method used peak arterial enhancement to determine the start of exposure, with the duration chosen at the radiologist's discretion. The measured-duration method used arterial and venous time-enhancement curves to determine exposure start and duration. Exposure duration, study adequacy, quality score, and maximum venous enhancement were compared among groups.

RESULTS

One hundred fifty-one examinations used the estimated-duration method, and 53 used measured-duration. The measured-duration method used a shorter exposure time (10 versus 15.8 seconds; P < .001). There was no statistically significant difference in the study adequacy rate, subjective quality score, or maximum venous enhancement. The radiation dose was reduced by 51% in the measured-duration method (3021 mGy × cm, 6.9 mSv, versus 1473 mGy × cm, 3.4 mSv). Both methods showed good agreement with DSA (κ = 0.88 for estimated-duration, κ = 1.0 for measured duration).

CONCLUSIONS

Exposure time in 4D-CTA can be reduced with dual time-enhancement curves to match exposure to physiology without degrading study adequacy or quality.

Four-dimensional computed tomography angiography is valuable in intracranial dural arteriovenous fistula diagnosis and fistula evaluation

This study was to evaluate the value of four-dimensional computed tomography angiography (4D-CTA) in the diagnosis of intracranial dural arteriovenous fistula (DAVF). This study included 16 patients who were diagnosed to have intracranial DAVF by digital subtraction angiography (DSA). The 4D-CTA was performed by Aquilion ONE multi-detector CT scanner (Toshiba Medical Systems, Japan) equipped with 320 × 0.5 mm detector rows. Standard biplane fluoroscopy equipments (Infinix, Toshiba Medical Systems, Japan and ADVANTX LC/LP, GE Medical Systems, Milwaukee, WI, USA) were applied in the diagnosis of intra-arterial DSA. Examinations were performed to evaluate the findings of DSA and 4D-CTA in each patient. The examination results were read by two independent readers in a blind manner. All results were documented on standardized scoring sheets. In all 16 cases, the same diagnosis results of intracranial DAVF were obtained from DSA and 4D-CTA. The results of subtype (Borden and Cognard classification), venous reflux and fistula sites were also accurately exhibited in 4D-CTA. In addition, there was a little discrepancy in identifying smaller and specific arterial branches and in distinguishing fistula type (focal or diffuse) using 4D-CTA. Good-to-excellent agreements were made between 4D-CTA and DSA. Therefore, 4D-CTA could be a feasible tool for the characterization of intracranial DAVF, with respect to determining fistula site and venous drainage.

Bone-Subtracted Spinal CT Angiography Using Nonrigid Registration for Better Visualization of Arterial Feeders in Spinal Arteriovenous Fistulas

BACKGROUND AND PURPOSE

Pretreatment diagnosis for the location of shunts and arterial feeders of spinal arteriovenous fistulas is crucial. This study aimed to evaluate the utility of subtracted CT angiography imaging by using nonrigid registration (R-CTA) in patients with spinal arteriovenous fistulas compared with conventional CTA imaging.

MATERIALS AND METHODS

The records of 15 consecutive subjects (mean age, 65 years; 2 women) who had undergone CTA and digital subtraction angiography for clinically suspected spinal arteriovenous fistula were reviewed. From CTA images obtained at the arterial and late arterial phases, warped images of the late arterial phase were obtained by using nonrigid registration that was adjusted to the arterial phase images. R-CTA images were then obtained by subtracting the warped images from the arterial phase images. The accuracies of using nonrigid registration and conventional spinal CTA and the time required for detecting arterial feeders in spinal arteriovenous fistulas were analyzed for each patient with DSA results as a standard reference. The difference between R-CTA and conventional spinal CTA was assessed by the Welch test and the McNemar χ(2) test.

RESULTS

R-CTA had a higher accuracy compared with conventional spinal CTA (80% versus 47%, P = .025). The time for interpretation was reduced in R-CTA compared with conventional spinal CTA (45.1 versus 97.1 seconds, P = .002).

CONCLUSIONS

Our subtracted CTA imaging by using nonrigid registration detects feeders of spinal arteriovenous fistulas more accurately and quickly than conventional CTA.

Four-dimensional computed tomography angiographic evaluation of cranial dural arteriovenous fistula before and after embolization

PURPOSE

This study aimed to evaluate the usefulness of four-dimensional CTA before and after embolization treatment with ONYX-18 in eleven patients with cranial dural arteriovenous fistulas, and to compare the results with those of the reference standard DSA.

PATIENTS AND METHODS

Eleven patients with cranial dural arteriovenous fistulas detected on DSA underwent transarterial embolization with ONYX-18. Four-dimensional CTA was performed an average of 2 days before and 4 days after DSA. Four-dimensional CTA and DSA images were reviewed by two neuroradiologists for identification of feeding arteries and drainage veins and for determining treatment effects. Interobserver and intermodality agreement between four-dimensional CTA and DSA were assessed.

RESULTS

Forty-two feeding arteries were identified for 14 fistulas in the 11 patients. Of these, 36 (85.71%) were detected on four-dimensional CTA. After transarterial embolization, one patient got partly embolized, and the fistulas in the remaining 10 patients were completely occluded. The interobserver agreement for four-dimensional CTA and intermodality agreement between four-dimensional CTA and DSA were excellent (κ=1) for shunt location, identification of drainage veins, and fistula occlusion after treatment.

CONCLUSION

Four-dimensional CTA images are highly accurate when compared with DSA images both before and after transarterial embolization treatment. Four-dimensional CTA can be used for diagnosis as well as follow-up of cranial dural arteriovenous fistulas in clinical settings.

4D-CTA in neurovascular disease: a review

CT angiography is a widely used technique for the noninvasive evaluation of neurovascular pathology. Because CTA is a snapshot of arterial contrast enhancement, information on flow dynamics is limited. Dynamic CTA techniques, also referred to as 4D-CTA, have become available for clinical practice in recent years. This article provides a description of 4D-CTA techniques and a review of the available literature on the application of 4D-CTA for the evaluation of intracranial vascular malformations and hemorrhagic and ischemic stroke. Most of the research performed to date consists of observational cohort studies or descriptive case series. These studies show that intracranial vascular malformations can be adequately depicted and classified by 4D-CTA, with DSA as the reference standard. In ischemic stroke, 4D-CTA better estimates thrombus burden and the presence of collateral vessels than conventional CTA. In intracranial hemorrhage, 4D-CTA improves the detection of the "spot" sign, which represents active ongoing bleeding.