December 2015, VOLUME 205
NUMBER 6

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December 2015, Volume 205, Number 6

Neuroradiology/Head and Neck Imaging

Original Research

Cerebral CT Venography Using a 320-MDCT Scanner With a Time-Density Curve Technique and Low Volume of Contrast Agent: Comparison With Fixed Time-Delay Technique

+ Affiliation:
1 All authors: Department of Neuroradiology, The Walton Centre for Neurology and Neurosurgery, Lower Ln, Fazakerley, Liverpool, L9 7LJ, United Kingdom.

Citation: American Journal of Roentgenology. 2015;205: 1269-1275. 10.2214/AJR.14.14200

ABSTRACT
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OBJECTIVE. The purpose of this study was to compare a cerebral CT venography (CTV) technique performed on a 320-MDCT scanner with the use of a time-density curve (TDC) and a small volume of IV contrast medium (35 mL, with 15 mL used for the test bolus) with CTV performed using an established reference technique in which scanning is performed at a fixed time delay of 30 seconds with the use of a larger volume of contrast medium (100 mL).

MATERIALS AND METHODS. The time of peak enhancement was determined from the TDC generated from a scan in which a test bolus dose was used. CTV was performed at the time of peak enhancement. The diagnostic quality of 31 CTV venograms acquired using this technique was compared retrospectively with the diagnostic quality of 29 CTV venograms obtained at a fixed time delay of 30 seconds. The densities in the major venous sinuses and the degree of arterial contamination on the scans acquired using the two techniques were compared using objective and semiobjective methods. The semiobjective assessments were made independently by two neuroradiologists.

RESULTS. Attenuation was higher in the venous structures seen on CTV images acquired using the TDC technique. Of the scans obtained using the TDC technique, the proportion deemed to be of good quality, on the basis of a grading scale, was statistically significantly higher (p < 0.05). Also, the degree of arterial contamination was statistically significantly lower (p < 0.05). The interrater agreement for semiobjective assessments ranged from good to very good.

CONCLUSION. We describe a CTV technique performed using a low volume of IV contrast medium and a TDC on a 320-MDCT scanner. This technique provides better venous opacification and lower arterial contamination compared with use of the fixed time-delay technique.

Keywords: 320-MDCT, cerebral CT venography, time-density curve

A 320-MDCT scanner has z-axis coverage of 16 cm and can acquire whole-brain volumetric data in 0.5 second. For CT angiographic procedures, the subsecond imaging time can be used to reduce the dose of iodinated contrast medium by scanning at the peak contrast attenuation of the vessel and thereby avoiding prolonged contrast medium administration [1]. A low volume of iodinated contrast medium can potentially reduce the risk of contrast medium–induced nephrotoxicity [2], in addition to providing an economic benefit. The fast imaging capability of a 320-MDCT has been used in different CT angiographic techniques [3]. Good diagnostic-quality 3D cerebral CT angiographic images produced by a 320-MDCT scanner with use of a low volume of contrast medium have been described elsewhere [4], with investigators synchronizing the time of scanning with the time of peak enhancement. The time of peak enhancement was determined from a time-density curve (TDC) obtained after a dynamic test dose scan. The same principle can be applied to imaging of the venous sinuses. We describe a technique for performing cerebral CT venography (CTV) with the use of a 320-MDCT scanner, where the time of maximum contrast enhancement of the venous sinuses is determined from the TDC by use of a small volume of test contrast dose. CTV is then performed by timing the scanning with the time of peak attenuation determined from the TDC. The subsecond imaging time thereby synchronizes with the time of peak enhancement of the venous sinuses.

A widely described and practiced CTV technique involves acquiring a scan at a fixed time delay (FTD) after administration of IV contrast medium by use of a pump injector. Because this technique relies on estimating the time of maximal venous enhancement, it typically requires a higher dose of contrast medium to generate a longer contrast bolus length to allow potential mistiming. After initial installation of our 320-MDCT scanner, we performed CTV with the use of an FTD of 30 seconds.

The importance of complete 3D visualization of the intracranial venous structures has been described elsewhere [5] and emphasizes the use of bone subtraction techniques for improved differentiation of vessels from bones [6]. In our practice, we also acquire a volumetric scan to use as a mask to generate subtracted 3D maximum-intensity-projection (MIP) images that allow assessment of vessels from all projections.

In this study, we retrospectively compared the image quality of the scans obtained using the FTD technique with that of scans acquired using the TDC technique, with use of a 320-MDCT scanner. The volume of contrast medium used in the TDC technique is only a fraction of the volume of contrast medium used in the FTD technique.

Materials and Methods
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Advice regarding the requirement of ethics approval for a retrospective comparative study was sought from the regional research ethics committee. Ethics approval was waived because the study involved evaluating retrospective data obtained as part of routine clinical care. Consecutive patients who underwent CTV with the FTD technique for 7 months before the TDC technique was introduced were included in the study, as were consecutive patients who underwent CTV with the TDC technique for 8 months after TDC was introduced as a routine CTV technique in our department. Patients with extensive venous sinus thrombosis that precluded measurement of attenuation in the main venous sinuses were excluded from the study.

Description of Fixed Time-Delay Technique

Unenhanced volume CT—CTV with use of the FTD technique was performed using a 320-MDCT scanner (Aquilion One, Toshiba Medical Systems). On the scout image, the scanning range was set from the C2 vertebra to the vertex. A volume CT examination was performed using the following scanning parameters: section thickness, 0.5 mm; section interval, 0.25 mm; tube voltage, 120 kV; tube current, 50–100 mAs; and matrix, 512 × 512. The data from this scan were used to generate subtracted MIP images.

The CT venography examination—Iopromide (300 mg I/mL; Ultravist 300, Bayer HealthCare) was administered via a 16-gauge cannula placed in the antecubital vein. A total of 100 mL of contrast medium was injected at a rate of 4 mL/s, with use of a power injector. The scan was obtained after a 30-second delay. The scanning parameters used were as follows: section thickness, 0.5 mm; tube voltage, 120 kV; tube current, 135 mAs; matrix, 512 × 512; and rotation time, 0.5 second. Images were reconstructed at 1-mm intervals.

Description of TDC Technique

CTV studies at our institution were performed using a 320-MDCT scanner (Aquilion One, Toshiba Medical Systems) with the TDC technique. The TDC technique has three components: the dynamic test bolus, the volume CT, and the CTV examinations.

Dynamic test bolus—A localizer scan was acquired at the midclival region through the mastoid, to show the sigmoid sinuses. Continuous single-slice low-dose scans (tube voltage, 80 kV; tube current, 100 mAs) were acquired 8 seconds after the start of injection of the contrast medium (iopromide), at a rate of one scan per second. A 15-mL test bolus of contrast medium was administered at the rate of 6 mL/s and was followed by a saline flush (20 mL administered at a rate of 6 mL/s). Scanning was continued until washout of the contrast medium from the venous sinuses was observed. The TDC was generated by placing an ROI in the sigmoid sinuses (Fig. 1A). The TDC (Fig. 1B) (obtained using the TDC tool that is part of the Aquilion scanner software written by Toshiba Medical Systems) was used to determine the time of peak enhancement and was rounded up to the next whole number.

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Fig. 1A —Test dose scan obtained using time-density curve (TDC) technique.

A, 40-year-old woman with headaches. ROI (circle 1) is placed over left sigmoid sinus in test dose scan.

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Fig. 1B —Test dose scan obtained using time-density curve (TDC) technique.

B, TDC is generated by test dose scan. Time of peak enhancement rounded up to next whole number is considered to be scanning delay.

Volume CT scan—A volume CT examination was then performed. The scanning parameters were the same as those used for the unenhanced volume scan (mask volume) acquired using the FTD technique previously described.

CT venography examination—The scan was performed at the peak time, as determined from the TDC. A total of 35 mL of contrast medium was administered at a rate of 6 mL/s and was followed by a normal saline bolus of 70 mL administered at a rate of 6 mL/s. The scanning parameters were the same as those previously described for CTV performed with use of the FTD technique. The mask volume was used to generate the subtracted 3D MIP images (Fig. 2).

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Fig. 2A —37-year-old woman with postpartum headaches. Three-dimensional maximum-intensity-projection (MIP) images from CT venography (CTV) performed in three different projections, with data acquired using two different techniques.

A, 50-year-old man with recent-onset headache with papilloedema. Three-dimensional MIP images obtained from CTV data acquired using time-density curve (TDC) technique are shown in posteroanterior (A), right anterior oblique (B), and left anterior oblique (C) projections. Reduced arterial contamination is seen on images acquired using TDC technique.

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Fig. 2B —37-year-old woman with postpartum headaches. Three-dimensional maximum-intensity-projection (MIP) images from CT venography (CTV) performed in three different projections, with data acquired using two different techniques.

B, 50-year-old man with recent-onset headache with papilloedema. Three-dimensional MIP images obtained from CTV data acquired using time-density curve (TDC) technique are shown in posteroanterior (A), right anterior oblique (B), and left anterior oblique (C) projections. Reduced arterial contamination is seen on images acquired using TDC technique.

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Fig. 2C —37-year-old woman with postpartum headaches. Three-dimensional maximum-intensity-projection (MIP) images from CT venography (CTV) performed in three different projections, with data acquired using two different techniques.

C, 50-year-old man with recent-onset headache with papilloedema. Three-dimensional MIP images obtained from CTV data acquired using time-density curve (TDC) technique are shown in posteroanterior (A), right anterior oblique (B), and left anterior oblique (C) projections. Reduced arterial contamination is seen on images acquired using TDC technique.

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Fig. 2D —37-year-old woman with postpartum headaches. Three-dimensional maximum-intensity-projection (MIP) images from CT venography (CTV) performed in three different projections, with data acquired using two different techniques.

D, 50-year-old man with recent-onset headache with papilloedema. Three-dimensional MIP images obtained from CTV data acquired using fixed time-delay technique are shown in posteroanterior (D), right anterior oblique (E), and left anterior oblique (F) projections.

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Fig. 2E —37-year-old woman with postpartum headaches. Three-dimensional maximum-intensity-projection (MIP) images from CT venography (CTV) performed in three different projections, with data acquired using two different techniques.

E, 50-year-old man with recent-onset headache with papilloedema. Three-dimensional MIP images obtained from CTV data acquired using fixed time-delay technique are shown in posteroanterior (D), right anterior oblique (E), and left anterior oblique (F) projections.

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Fig. 2F —37-year-old woman with postpartum headaches. Three-dimensional maximum-intensity-projection (MIP) images from CT venography (CTV) performed in three different projections, with data acquired using two different techniques.

F, 50-year-old man with recent-onset headache with papilloedema. Three-dimensional MIP images obtained from CTV data acquired using fixed time-delay technique are shown in posteroanterior (D), right anterior oblique (E), and left anterior oblique (F) projections.

The diagnostic quality of scans obtained using the TDC technique was compared with that of scans obtained using the FTD technique, by use of the following methods: objective comparison of attenuation in the venous sinuses, objective comparison of arterial contamination, semiobjective assessment of enhancement of venous sinuses, and semiobjective comparison of arterial contamination.

Objective comparison of attenuation in the venous sinuses—CTV scans (acquired using both the TDC and FTD techniques) were randomly selected, and attenuation in six different venous structures was measured by placing the ROI cursor on those venous structures (Fig. 3). The area of the ROI used was approximately 2.5–3.0 mm2. Attenuation was calculated in the following structures: the superior sagittal sinus, transverse sinus, straight sinus, torcular herophili, sigmoid sinus, and internal jugular vein at the jugular foramen. The densities measured in these structures by use of the two different techniques were compared using the t test.

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Fig. 3 —Image shows position of ROI (green line) in left transverse sinus for attenuation measurement. P = posterior, AV = average, AR = area.

Objective comparison of arterial contamination—Comparison of arterial contamination was performed by measuring the ratio of the contrast attenuation in one of the sigmoid sinuses to attenuation in the cavernous segment of one of the internal carotid arteries (ICAs). This ratio was considered to be a tool for indirect comparison of iodine load in these vascular structures. A lower ratio would therefore suggest greater arterial contamination with contrast medium. The average of the ratios in scans acquired using the two techniques (TDC vs FTD) was compared using the t test.

Semiobjective assessment of enhancement of venous sinuses—The extent of venous sinus enhancement was graded and scored on the basis of the MIP images. Scans with clear visualization with optimal opacification of the superior sagittal, transverse, straight, and sigmoid sinuses were considered to be of good quality (score, 3). Scans with clear visualization of the superior sagittal, transverse, straight, and sigmoid sinuses but without optimal opacification of one or more these structures, were deemed acceptable (score, 2). If one or more of the aforementioned sinuses were not clearly visualized, then the scan quality was considered nondiagnostic (score, 1). The difference in the grade of the scans acquired using the TDC and FTD techniques was measured by use of the Wilcoxon rank sum test.

Grading of the scans was performed by two neuroradiologists, one of whom had more than 10 years of experience (rater 1) and one of whom had 2 years of experience (rater 2). The difference in the grades for the scans acquired with the TDC and FTD techniques was measured using the Wilcoxon rank sum test. The kappa score was calculated to determine the degree of agreement between the neuroradiologists.

Semiobjective comparison of arterial contamination—The degree of arterial contamination was also assessed semiobjectively by evaluating the MIP images and then was graded and scored. Scans with opacification of the distal or peripheral arteries only were graded as having mild arterial contamination (score, 3). However, scans with opacification of the distal or peripheral arteries and the insular middle cerebral artery (MCA) were considered to have moderate arterial contamination (score, 2). Scans showing opacification of the distal arteries, MCA, and supraclinoid ICA were deemed as having marked arterial contamination (score, 1). Grading and scoring were done by the same two neuroradiologists. The difference in the grading of arterial contamination in scans obtained using the two different techniques (FTD and TDC) was measured with use of the Wilcoxon rank sum test. Again, the kappa score was calculated to assess interrater agreement.

Results
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A total of 29 patients (10 male and 19 female patients; age range, 17–77 years) underwent CTV performed using the FTD technique. Thirty-one patients (18 men and 13 women; age range, 18–81 years) underwent CTV performed using the TDC technique.

When the FTD technique was used, the average densities in the predefined venous sinuses were as follows: superior sagittal sinus, 190.90 HU (SD, 89.73 HU); transverse sinus, 186.20 HU (73.96 HU); straight sinus, 218.72 HU (69.96 HU); torcular herophili, 217.93 HU (75.59 HU); sigmoid sinus, 190.24 HU (84.66 HU); and internal jugular vein at the jugular foramen, 189.76 HU (85.02 HU). In comparison, when the TDC technique was used, the average densities in six predefined venous structures were as follows: superior sagittal sinus, 206.26 HU (51.73 HU); transverse sinus, 218.45 HU (51.24 HU); straight sinus, 226.10 HU (64.96 HU), torcular herophili, 229.35 HU (55.76 HU); sigmoid sinus, 226.32 HU (62.73 HU); and internal jugular vein at the jugular foramen, 208.84 HU (59.29 HU). The differences in average densities were not statistically significant (p > 0.05).

The average ratio of the attenuation in the sigmoid sinus to the attenuation in the cavernous segment of the ICA in scans obtained using the FTD technique was 1.87, whereas the same ratio was 2.04 (p = 0.413) when scans were obtained using the TDC technique.

For the 29 scans obtained using the FTD technique, rater 1 semiobjectively graded venous sinus opacification as follows: 16 scans (55%) were deemed to be of good diagnostic quality, nine (31%) were of acceptable quality, and four (14%) were nondiagnostic. For the 31 scans obtained using the TDC technique, rater 1 graded venous sinus opacification as follows: 26 scans (84%) were considered to be of good diagnostic quality, four (13%) were of acceptable quality, and one (3%) was nondiagnostic. Rater 2 semiobjectively graded scans acquired using the FTD technique as follows: 15 scans (52%) were of good diagnostic quality, 10 (34%) were of acceptable quality, and four (14%) were nondiagnostic. Rater 2 graded scans obtained using the TDC technique as follows: 24 scans (77%) were found to be of good diagnostic quality, six (20%) were of acceptable quality, and one (3%) was nondiagnostic. The results are shown in Figure 4. The difference in the scores between the two techniques was also statistically significant (p < 0.05) for both raters, with the TDC technique favored.

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Fig. 4 —Results of semiobjective assessment by raters 1 and 2 of diagnostic quality of CT venography images obtained using time-density curve (TDC) technique versus fixed time-delay (FTD) technique.

When semiobjectively grading arterial contamination on the 29 scans obtained using the FTD technique, rater 1 found that nine scans (31%) showed mild contamination, 12 (41%) showed moderate contamination, and eight (28%) showed marked contamination. For the 31 scans acquired using the TDC technique, grading by rater 1 was as follows: 26 scans (84%) showed mild contamination, two scans (6%) showed moderate contamination, and three scans (10%) showed marked contamination. For rater 2, the results of semiobjective grading of arterial contamination by scans obtained by the FTD technique were as follows: contamination was mild on nine scans (31%), moderate on 11 scans (38%), and marked on nine scans (31%). For scans obtained using the TDC technique, the results were as follows: contamination was mild on 23 scans (74%), moderate on five scans (16%), and marked on three scans (10%). The difference in arterial contamination was found to be statistically significant (p < 0.05) for results of evaluations by both raters, with greater arterial contamination seen on images obtained using the FTD technique. The results are summarized in Figure 5.

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Fig. 5 —Results of comparison of arterial contamination by raters 1 and 2 in CT venography images obtained using time-density curve (TDC) technique versus fixed time-delay (FTD) technique.

The kappa scores indicating interrater agreement for semiobjective assessment of venous sinus enhancement were 0.76 (denoting good interrater agreement) and 0.80 (also denoting good interrater agreement) for the FTD and TDC techniques, respectively. For the degree of arterial contamination assessed, kappa scores were 0.89 (denoting very good interrater agreement) and 0.73 (denoting good interrater agreement) for the FTD and TDC techniques, respectively.

The average radiation dose resulting from CTV examinations performed using the FTD and TDC techniques had a dose-length product of 1064.35 mGy⋅cm, with an effective dose of 2.45 mSv. The average radiation dose during dynamic scanning performed with the test dose used in the TDC technique had a dose length product of 58.24 mGy⋅cm, with an effective dose of 0.13 mSv.

Discussion
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Although there is a large volume of available literature on intracranial CT angiography, we think that there is a relative lack of studies evaluating cerebral CTV techniques, given the major advancements in CT technology. We are not aware of any previous study that has evaluated intracranial CTV examinations performed using a 320-MDCT scanner. With advances in CT technology and faster scanning speeds, scanning time and the contrast dose used can be optimized. At the same time, the diagnostic quality of these scans must be compared with that achieved using long-established techniques. Our study is a step in this direction.

Cerebral venous thrombosis is an uncommon form of stroke that is associated with diverse presentations, with diagnosis and management of this condition often resulting in challenges [7]. CTV has emerged as a rapid, reliable, and readily available method of investigating cerebral venous thrombosis [8]. The cerebral veins and the venous sinuses have a complex anatomy, and the variation in anatomic features poses a challenge in the evaluation of the cerebral venous structures [5]. Optimum opacification of the venous structures therefore becomes important in making an accurate diagnosis of venous sinus thrombosis and enabling recognition of normal variants. With digital subtraction angiography considered the reference standard, the sensitivity of CTV has been reported to be 95% (with multiplanar reformatted images) [9]. CTV has previously been reported to be superior to MR venography in the identification of cerebral veins and dural sinuses, and it is at least equivalent to MR venography in establishing a diagnosis of dural sinus thrombosis [10]. In a more recent study that used time-of-flight MR venography as the reference standard, and with consideration of the venous structures involved, CTV has been reported to have sensitivity of 75–100%, specificity of 81–100%, positive predictive value of 75–100%, negative predictive value of 89–100%, and overall accuracy of 90–100% [11].

To our knowledge, Casey et al. [12] were the first to describe CTV examination performed after administration of IV contrast medium by means of a pump injector. With use of this technique, a total of 90 mL of IV contrast medium was administered at a rate of 3 mL/s, with a prescanning delay of 40 seconds. Other studies have reported a scanning delay of 40 or 45 seconds [9, 13] and administration of an IV contrast volume of 100 mL at a rate of 3 mL/s. CTV examinations performed using CT scanners with a smaller detector size require longer scanning durations and a larger volume of contrast medium to provide a longer contrast bolus. With our technique, the total contrast volume is approximately half the volume used in previously reported techniques (i.e., a total volume of 50 mL, a test dose of 15 mL, and 35 mL used for the CTV examination). Use of this dose size is made possible by synchronizing the subsecond scanning time of the 320-MDCT system with the time of peak enhancement of the venous sinuses; the time is determined from the peak of the TDC obtained from the test scan.

Our study shows that the attenuation in the six major venous structures, as seen on images obtained using the TDC technique, is higher than that seen on images obtained using the FTD technique, although the values are comparable and the differences are not statistically significant. However, considering the semi-objective assessment of the attenuation in the venous structures previously described, the difference in the grade of the scans acquired using the TDC and FTD techniques was statistically significant (i.e., greater attenuation in venous structures was achieved with use of the TDC technique). Therefore, this study provides a quality assurance tool that shows that the TDC technique, which is new to our institution, is not an inferior technique compared with the older FTD technique. In fact, this technique can generate CTV images on which attenuation in the venous sinus is greater than that seen on CTV images obtained using the FTD technique, with the added benefit that it uses a fraction of the contrast dose used by the FTD technique.

Attenuation achieved in the venous sinuses is not the only determinant of the diagnostic quality of a CTV image. In addition to the high attenuation achieved in the venous sinuses, reduced superimposed arterial opacification would also improve visualization of the venous sinuses. Arterial contamination also indicates persistent iodine load in the arterial bed, which is not of diagnostic value in CTV studies. In our study, we measured attenuation in the cavernous segment of the ICA for indirect measurement of arterial contamination. The ratio of the contrast attenuation in one of the sigmoid sinuses to the attenuation in the cavernous segment of one of the ICAs may be deemed an indirect measurement of iodine load in the artery relative to that in the venous sinuses. The average ratio was greater for scans obtained using the TDC technique compared with scans obtained using the FTD technique, although the value did not reach statistical significance. We also assessed the MIP images for superimposed arterial contamination, which may obscure the venous structures. After the semiobjective assessment, the difference in values was statistically significant, favoring lower contamination in CTV performed using the TDC technique.

Matsumoto et al. [14] described separate arterial and venous phases in a single 3D CT cerebral angiography procedure. This study reports determination of the optimal scanning delay to generate separate CT angiography and CTV values for TDCs obtained from a dynamic CT performed using a test dose. The authors described how the peak-to-peak time was used to determine the interscan time and, therefore, the time of scanning in the venous phase. The technique was performed on a 16-MDCT scanner; therefore, a scanning time of longer duration was required. Our technique uses the test bolus scan to determine the peak of venous enhancement. The subsecond scanning time also enables data acquisition time to be limited to the time of peak enhancement rather than a longer period. In addition, our study compares the quality of the scans acquired using this technique with the quality of scans acquired using the FTD technique, taking into account both the attenuation achieved and arterial contamination. Our study also validates the findings of Matsumoto et al. [14] and confirms that good-quality venous phase enhancement can be obtained by determining the scanning time from the TDC.

The FTD technique does not take into consideration the cardiovascular status of individual patients. Variation in cardiovascular status can significantly affect the time to peak enhancement of the venous sinuses and therefore the quality of the scan. A longer contrast bolus can compensate for this but at the cost of a higher contrast volume requirement and increased frequency of superimposed arterial contamination. The TDC technique, on the other hand, has the advantage of tailoring the timing by determining the time of peak enhancement of the venous sinuses by the test dose. The effect of variation in cardiovascular status can thus be virtually nullified. In our study, we have been able to generate CTV images of good diagnostic quality with use of the TDC technique with a smaller volume of contrast medium for all our patients, regardless of their cardiovascular status. It has been shown that the time to peak concentration cannot be calculated using hemodynamic parameters, and the usefulness of the test bolus dose in determining the venoarterial circulation time for cerebral vessels has been shown [15].

The feasibility of bolus tracking as a technique for cerebral CTV is questionable. In our experience, slow and variable flow in the venous structures makes it difficult to select a specific threshold of enhancement for triggering the scan consistently. Also, the variation in venous anatomy may make it difficult to preselect a venous structure for triggering purposes. We therefore did not consider bolus tracking as a method for routinely performing CTV. The FTD technique was used at our institution before introduction of the TDC technique. The TDC technique is now our technique of choice for performing CTV (Fig. 6).

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Fig. 6A —28-year-old woman with severe headache. CT venography (CTV) was performed using time-density curve technique.

A, Axial CTV image shows left transverse sinus thrombosis.

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Fig. 6B —28-year-old woman with severe headache. CT venography (CTV) was performed using time-density curve technique.

B, Maximum-intensity-projection CTV image shows reduced filling in left sigmoid sinus. Left transverse sinus is not visualized.

All the venous sinuses may not fill with contrast medium at the same time. Therefore, comparison of the degree of arterial contamination, as measured by the ratio of attenuation (expressed in Hounsfield units) in the cavernous segment of one of the ICAs to attenuation in one of the sigmoid sinuses, may not be accurate. Nevertheless, this ratio may be considered an indirect tool for measuring arterial contamination. A criticism of the TDC technique could be the additional radiation dose involved during the dynamic scanning after a test bolus of contrast medium. This is an inherent part of any technique involving a test dose. The additional radiation from the test scanning is only 5.3% of the average radiation involved in the actual CTV. We also believe that the TDC technique would reduce the need for repeat examination, which may have to be performed because of suboptimal diagnostic image quality as a result of variation in cardiovascular status. Technicians using the TDC technique have also reported greater confidence in administering IV contrast medium at a higher flow rate, because the initial scanning dose would test for the patency and efficacy of the venous cannulation. As in our previous study reporting use of the TDC technique in CT angiography [4], no complications were encountered with administration of contrast medium at a flow rate of 6 mL/s.

Conclusion
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CTV images acquired using a 320-MDCT scanner with the TDC technique are of high diagnostic quality, with the additional benefit that this technique uses a fraction of the contrast medium used by the FTD technique. The attenuation achieved in the venous structures when the TDC technique is used is higher than the attenuation achieved when the FTD technique is used. The degree of superimposed arterial contamination is also lower for scans obtained using the TDC technique compared with scans acquired using the FTD technique.

Acknowledgments
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We thank Debasree Purkayastha, Statistician and Senior Analyst, Public Health England, for helping with statistical analysis of the anonymized data. We also thank Christine Elizabeth Denby, Research Fellow, Department of Neuroradiology, The Walton Centre, Liverpool, United Kingdom, for reviewing the manuscript.

The study was performed using an Aquilion One scanner (Toshiba Medical Systems). Toshiba Medical Systems UK provided support to the Department of Neuroradiology, The Walton Centre for Neurology and Neurosurgery, Liverpool, United Kingdom, to facilitate research by funding the post of a research fellow under the supervision of K. Das. Acknowledgment is given to this research fellow, but the fellow's contribution to this study was insufficient to merit authorship.

References
Previous section
1. Sorantin E, Riccabona M, Stücklschweiger G, Guss H, Fotter R. Experience with volumetric (320 rows) pediatric CT. Eur J Radiol 2013; 82:1091–1097 [Google Scholar]
2. Gleeson TG, Bulugahapitiya S. Contrast-induced nephropathy. AJR 2004; 183:1673–1689 [Abstract] [Google Scholar]
3. Siebert E, Bohner G, Dewey M, et al. 320-slice CT neuroimaging: initial clinical experience and image quality evaluation. Br J Radiol 2009; 82:561–570 [Google Scholar]
4. Das K, Biswas S, Roughley S, Bhojak M, Niven S. 3D CT cerebral angiography technique using a 320-detector machine with a time-density curve and low contrast medium volume: comparison with fixed time delay technique. Clin Radiol 2014; 69:e129–e135 [Google Scholar]
5. Seo H, Choi DS, Shin HS, Cho JM, Koh EH, Son S. Bone subtraction 3D CT venography for the evaluation of cerebral veins and venous sinuses: imaging techniques, normal variations, and pathologic findings. AJR 2014; 202:[web]W169–W175 [Abstract] [Google Scholar]
6. Venema HW, Hulsmans FJ, den Heeten GJ. CT angiography of the circle of Willis and intracranial internal carotid arteries: maximum intensity projection with matched mask bone elimination—feasibility study. Radiology 2001; 218:893–898 [Google Scholar]
7. Saposnik G, Barinagarrementeria F, Brown RD Jr, et al. Diagnosis and management of cerebral venous thrombosis: a statement for healthcare professionals from the American Heart Association/American Stroke Association. Stroke 2011; 42:1158–1192 [Google Scholar]
8. Leach JL, Fortuna RB, Jones BV, Gaskill-Shipley MF. Imaging of cerebral venous thrombosis: current techniques, spectrum of findings, and diagnostic pitfalls. RadioGraphics 2006; 26(suppl 1):S19–S41 [Google Scholar]
9. Wetzel SG, Kirsch E, Stock KW, Kolbe M, Kaim A, Radue EW. Cerebral veins: comparative study of CT venography with intraarterial digital subtraction angiography. AJNR 1999; 20:249–255 [Google Scholar]
10. Ozsvath RR, Casey SO, Lustrin ES, Alberico RA, Hassankhani A, Patel M. Cerebral venography: comparison of CT and MR projection venography. AJR 1997; 169:1699–1707 [Abstract] [Google Scholar]
11. Khandelwal N, Agarwal A, Kochhar R, et al. Comparison of CT venography with MR venography in cerebral sinovenous thrombosis. AJR 2006; 187:1637–1643 [Abstract] [Google Scholar]
12. Casey SO, Alberico RA, Patel M, et al. Cerebral CT venography. Radiology 1996; 198:163–170 [Google Scholar]
13. Rodallec MH, Krainik A, Feydy A, et al. Cerebral venous thrombosis and multidetector CT angiography: tips and tricks. RadioGraphics 2006; 26(suppl 1):S5–S18 [Google Scholar]
14. Matsumoto M, Kodama N, Sakuma J, et al. 3DCT arteriography and 3D-CT venography: the separate demonstration of arterial-phase and venous-phase on 3D-CT angiography in a single procedure. AJNR 2005; 26:635–641 [Google Scholar]
15. Puskás Z, Schuierer G. Determination of blood circulation time for optimizing contrast medium administration in CT angiography. Radiologe 1996; 36:750–757 [Google Scholar]
Address correspondence to S. Biswas ().

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