Inverse Problem Algorithm-Based Time-Resolved Imaging of Head and Neck Computed Tomography Angiography Contrast Kinetics with Clinical Testification.

This study mitigated the challenge of head and neck CT angiography by IPA-based time-resolved imaging of contrast kinetics. To this end, 627 cerebral hemorrhage patients with dizziness, brain aneurysm, stroke, or hemorrhagic stroke diagnosis were randomly categorized into three groups, namely, the original dataset (450), verification group (112), and in vivo testified group (65), in the Affiliated BenQ Hospital of Nanjing Medical University. In the first stage, seven risk factors were assigned: age, CTA tube voltage, body surface area, heart rate per minute, cardiac output blood per minute, the actual injected amount of contrast media, and CTA delayed trigger timing. The expectation value of the semi-empirical formula was the CTA number of the patient's left artery (LA). Accordingly, 29 items of the first-order nonlinear equation were calculated via the inverse problem analysis (IPA) technique run in the STATISTICA 7.0 program, yielding a loss function and variance of 3.1837 and 0.8892, respectively. A dimensionless AT was proposed to imply the coincidence, with a lower AT indicating a smaller deviation between theoretical and practical values. The derived formula was confirmed for the verification group of 112 patients, reaching high coincidence, with average ATavg and standard deviation values of 3.57% and 3.06%, respectively. In the second stage, the formula was refined to find the optimal amount of contrast media for the CTA number of LA approaching 400. Finally, the above procedure was applied to head and neck CTA images of the third group of 65 patients, reaching an average CTA number of LA of 407.8 ± 16.2 and finding no significant fluctuations.

Image quality improvement in head and neck CT angiography: Individualized post-trigger delay versus fixed delay.

PURPOSE: To compare the contrast media opacification of head and neck CT angiography (CTA) between conventional fixed trigger delay and individualized post-trigger delay (PTD). METHODS: In this prospective study (April-October 2022), 196 consecutive participants were randomly divided into two groups to perform head and neck CTA in bolus tracking with either an individualized PTD (Group A) or a fixed 4-second PTD (Group B). All CT and contrast media protocol parameters were consistent between the two groups. One reader evaluated objective image quality, while two readers rated subjective image quality. Objective image quality was compared between groups via two-sample t-test, while the subjective ratings were compared with chi-square analysis. RESULTS: Participants' clinical information including sex, age, weight, body weight index (BMI), and heart rate were not statistically different between two groups (all p > 0.05). Individualized PTD ranging from 3.5 to 7.9 s (average 5.6 s), which is shorter than fixed delays (p < 0.05). Both readers rated better subjective image quality for the Group A (p < 0.05). The mean vessel enhancement was significantly higher in Group A in all vessels (all p < 0.05). CONCLUSIONS: Compared to the fixed post-trigger delay in bolus tracking technique, individualized post-trigger delay could achieve reliable scan timing, optimize vessel opacification and obtain better image quality for head and neck CT angiography.

A preliminary study on the combination of high iodine flow rate and high noise index in reducing the radiation dose of CT angiography for head and neck / 中国医学装备

Objective:To carry out preliminarily study on the combination of high iodine flow rate (IDR) and high noise index (NI) in reducing radiation dose of CT angiography (CTA) for head and neck.Methods:A total of 120patients with lesions on head and neck who underwent head and neck CTA in the hospital were divided into high IDR combined with high NI group (high IDR+NI group, 50 cases) , middle IDR combined with middle NI group (middle IDR+NI group, 40 cases) and low IDR combined with low NI group (low IDR+NI group, 30 cases) according to the random number table method.The scanned images were reconstructed by the iterative reorganization algorithm (ASiR) 2.0.The CT values of head and neck, signal to noise ratio (SNR) , contrast noise ratio (CNR) of all images in three groups were analyzed objectively and scored subjectively.And the CT dose index (CTDI) , dose length product (DLP) , effective radiation dose (ED) of the iodine intake and radiation dose were recorded.Results:The differences of CT value of ascending aorta, upper common carotid artery or lower internal carotid artery among the three groups were no significant, respectively.The SNR and CNR in high IDR+NI group were significantly higher than those in middle IDR+NI group and low IDR+NI group (F=47.908, F=52.525, P<0.05) , respectively.And there was no significant difference in subjective scores among the three groups.The differences of CTDI, DLP and ED in high IDR+NI group were significantly lower than those in middle IDR+NI group and low IDR+NI group (F=224.861, F=199.610, F=412.443, P<0.05) , respectively.Conclusion:The combination of high IDR and high NI for patients who undergoes head and neck CT can reduce the radiation dose when ensure the image quality, and it is worthy in clinical application.