Preliminary study of time maximum intensity projection computed tomography imaging for the detection of early ischemic change in patient with acute ischemic stroke

Imaging features of cardioembolic stroke on 4-dimensional computed tomography angiography

Background

Identifying cardioembolic stroke is important for the decision-making of endovascular treatment and anticoagulation therapy. We aimed to explore the features of cardioembolic stroke on 4-dimensional (4D) computed tomography angiography (4D-CTA) and assess whether these features can assist in classifying stroke etiology.

Methods

In this retrospective study, we analyzed the images of 294 patients with acute ischemic stroke (AIS) from July 2020 to February 2022 at the First Affiliated Hospital of Chongqing Medical University, which had been consecutively collected. The data of 110 patients with occlusion of the M1/M2 segment of the middle cerebral artery (MCA) with/without intracranial internal carotid artery (ICA) occlusion were analyzed to calculate the clot burden score (CBS) and collateral score (CS), and the data of 88 patients with a clear origin and distal part were analyzed to measure clot length. Maximum intensity projection (MIP) and time MIP (tMIP) post-processing were used to assess the clot features. The Mann-Whitney U test was used to compare the clot characteristics between the 2 groups. Binary logistic regression was performed to assess the association between the image characteristics and cardioembolic stroke. Moreover, the receiver operating characteristic (ROC) curve was used to test the diagnostic efficacy of MIP/tMIP clot features in classifying cardioembolic stroke.

Results

Age, high-risk factors for cerebrovascular disease, high/medium-risk sources of cardioembolic stroke, clot length, CBS, and CS were significantly different between the cardioembolic stroke group and non-cardioembolic stroke group (P<0.05). In the cardioembolic stroke group, the median MIP and tMIP clot length was 12 mm [interquartile range (IQR), 8.3-17.4 mm] and 9.3 mm (IQR, 6.8-14.3 mm), respectively. In the non-cardioembolic stroke group, the median MIP and tMIP clot length was 6.5 mm (IQR, 4.7-11.5 mm) and 5.8 mm (IQR, 3.9-10.6 mm), respectively. Binary logistic regression showed that cardioembolic stroke was significantly associated with MIP-clot length [odds ratio (OR), 1.15; 95% confidence interval (CI): 1.02-1.29; P<0.05], tMIP-clot length (OR, 1.18; 95% CI: 1.02-1.36; P<0.05), and tMIP-CBS (OR, 3.96; 95% CI: 1.08-14.58; P<0.05). The area under the ROC curve (AUC) values of MIP clot length for identifying cardioembolic stroke were 0.75 (95% CI: 0.65-0.84, P<0.05), with a cut-off value of >7.4 mm [sensitivity: 84.62% (95% CI: 69.50-94.10%); specificity: 59.18% (95% CI: 44.20-73.00%)]. The AUC value of tMIP clot length was 0.72 (95% CI: 0.61-0.81, P<0.05), with a cut-off value of >5.4 mm [sensitivity: 92.31% (95% CI: 79.10-98.40%); specificity: 48.98% (95% CI: 34.40-63.70%)].

Conclusions

Clot length and CBS were overestimated on MIP images. Among the clot characteristics, clot length could identify cardioembolic stroke.

Evaluation of the lower extremity blood supply in no-option critical limb ischemia patients with stem cell transplantation by time maximum intensity projection CT perfusion: A single-centre prospective study

OBJECTIVES

Cell therapy has had satisfactory safety and efficacy outcomes for no-option critical limb ischaemia (NO-CLI) patients. In the current study, we aimed to compare the image quality of ischaemic lower limb blood vessels shown on volumetric CT-based time maximum intensity projection CT perfusion (t-MIP CTP) versus single-phase CTA (sCTA). We also tried to quantify the blood flow of the ischaemic lower extremity based on the t-MIP technique, not only to precisely show the dynamic change in blood flow from before to after cell therapy but also to detect any relationship between this change and patient prognosis.

METHODS

A total of 31 patients with thromboangiitis obliterans (TAO)-induced NO-CLI who had been referred from the department of vascular surgery to undergo autologous stem cell transplantation into a single limb from January 2020 to March 2021 were prospectively enrolled in this study. Preoperative sCTA or t-MIP CTP and postoperative 1-month t-MIP CTP were performed in all patients. Clinical outcomes, including the 1-month ankle-brachial index (ABI) and 3-month CLI status, were also analysed. Image quality, including objective scores (attenuation, signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]), subjective scores and collateral scores, was compared between preoperative sCTA and t-MIP CTP. Vascular volume was calculated as the total volume (mL) of lower limb arteries within the scanning range. All images and calculations were performed by 2 separate radiologists. Receiver operating characteristic curves were drawn to reveal the sensitivity and specificity of vascular volume and ABI in predicting prognosis.

RESULTS

Both sCTA and t-MIP CTP images exhibited good quality for diagnosis. t-MIP CTP images showed significantly higher attenuation, SNR and CNR in all arterial segments (popliteal artery, anterior tibial artery, posterior tibial artery and peroneal artery). In subjective and collateral score evaluations, t-MIP CTP images were also significantly better than sCTA images (both p < .05). At 1 month after transplantation, both vascular volume and ABI showed significant improvement (both p < .01). At 3 months after transplantation, 38.71% of patients (12/31) achieved CLI relief (Rutherford class < 4). Through the receiver operating characteristic (ROC) curve, the 1-month vascular volume increase ratio showed better ability to predict the 3-month prognosis (radiologist 1: AUC, 0.757; sensitivity, 0.750; specificity, 0.840; radiologist 2: AUC, 0.803; sensitivity, 0.500; specificity, 1.000) than the 1-month ABI increase ratio (AUC, 0.607; sensitivity, 0.230; specificity, 0.820) or 1-month ABI (AUC, 0.410; sensitivity, 0.080; specificity, 0.580).

CONCLUSION

t-MIP CTP showed significantly higher-quality images of ischaemic limb vascularity than sCTA. t-MIP CTP can reveal the anatomical information of collaterals more accurately, which is of great importance for NO-CLI patients undergoing cell transplantation. The 1-month vascular volume increase ratio can predict the 3-month prognosis more precisely on this basis.

Is it feasible to measure pulmonary vein data using volume rendering images?

BACKGROUND

Pulmonary vein (PV) data are commonly measured on multiplanar image reformation (MPR) images and volume rendering (VR) images.

PURPOSE

To compared and analyze the advantages and disadvantages of PV data based on VR images and MPR images.

MATERIAL AND METHODS

A total of 94 patients with atrial fibrillation (AF) with imaging data were included in the study. The respective image postprocessing time and the three surgical interventionists' preferences for the two images were recorded. A paired t-test or chi-square test was used to compare their difference, and P < 0.05 was considered statistically significant.

RESULTS

There was no statistically significant difference between the data values including the maximal and minimal ostial diameters of the left superior PV (LSPV), the left inferior PV (LIPV), the right superior PV (RSPV), and the right inferior PV (RIPV) obtained by VR and MPR images (P > 0.05). Yet, the mean postprocessing time of VR images (15.10 ± 3.05 min) was shorter compared to MPR images (16.54 ± 2.60 min) (t = 22.84, P < 0.05). All three surgical interventionists preferred VR images (accounted for 85.1%, 86.2%, and 84.0%, respectively), and there was no statistical difference in the degree of image preference among the three (chi-square = 0.596, P = 0.963).

CONCLUSION

PV data measurement could be performed on both VR and MRP images; however, the data on VR images were more intuitive and more accessible for interventional surgeons.

Temporal averaging angiographic reconstructions from whole-brain CT perfusion for the detection of vasospasm

PURPOSE

The aim of this study is to evaluate the image quality and diagnostic performance of angiographic images reconstructed from whole-brain CT perfusion (CTP) using temporal averaging compared to CT angiography (CTA) for the detection of vasospasm.

MATERIALS AND METHODS

39 CT studies in 28 consecutive patients who underwent brain CTA with CTP for suspected vasospasm between September 2020 and May 2021 were retrospectively evaluated. The image quality of these two vascular imaging techniques was assessed either quantitatively (image noise, vascular enhancement, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios,) and qualitatively (4 criteria assessed on a 5-point scale). Intra and interobserver agreements and a diagnostic confidence score on the diagnosis of vasospasm were measured. Radiation dose parameters (volume CT dose index (CTDI_vol) and dose-length product (DLP)) were recorded.

RESULTS

Both SNR and CNR were significantly higher with temporal averaging compared to CTA, increasing by 104% and 113%, respectively (p<0.001). The qualitative assessment found no significant difference in overall image quality between temporal averaging (4.33 ± 0.48) and brain CTA (4.19 ± 0.52) (p = 0.12).There was a significant improvement in intravascular noise and arterial contrast enhancement with temporal averaging. The evaluation of intra and interobserver agreements showed a robust concordance in the diagnosis of vasospasm between the two techniques.

CONCLUSIONS

Temporal averaging appeared as a feasible and reliable imaging technique for the detection of vasospasm. The use of temporal averaging, replacing brain CTA, could represent a new strategy of radiation and contrast material doses reduction in these patients.

Preliminary Application of a Quantitative Collateral Assessment Method in Acute Ischemic Stroke Patients With Endovascular Treatments: A Single-Center Study

Objectives: To develop an efficient and quantitative assessment of collateral circulation on time maximum intensity projection CT angiography (tMIP CTA) in patients with acute ischemic stroke (AIS). Methods: Eighty-one AIS patients who underwent one-stop CTA-CT perfusion (CTP) from February 2016 to October 2020 were retrospectively reviewed. Single-phase CTA (sCTA) and tMIP CTA were developed from CTP data. Ischemic core (IC) volume, ischemic penumbra volume, and mismatch ratio were calculated. The Tan scale was used for the qualitative evaluation of collateral based on sCTA and tMIP CTA. Quantitative collateral circulation (CCq) parameters were calculated semi-automatically with software by the ratio of the vascular volume (V) on both hemispheres, including tMIP CTA V_CCq and sCTA V_CCq. Spearman correlation analysis was used to analyze the correlation of collateral-related parameters with final infarct volume (FIV). ROC and multivariable regression analysis were calculated to compare the significance of the above parameters in clinical outcome evaluation. The analysis time of the observers was also compared. Results: tMIP CTA V_CCq (r = 0.61, p < 0.01), IC volume (r = 0.66, p < 0.01), Tan score on tMIP CTA (r = 0.52, p < 0.01) and mismatch ratio (r = 0.60, p < 0.01) showed moderate negative correlations with FIV. tMIP CTA V_CCq showed the best prognostic value for clinical outcome (AUC = 0.93, p < 0.001), and was an independent predictive factor of clinical outcome (OR = 0.14, p = 0.009). There was no difference in analysis time of tMIP CTA V_CCq among observers (p = 0.079). Conclusion: The quantitative evaluation of collateral circulation on tMIP CTA is associated with clinical outcomes in AIS patients with endovascular treatments.

Quick evaluation of lower leg ischemia in patients with peripheral arterial disease by time maximum intensity projection CT angiography: a pilot study

Background

The purpose of this study is to evaluate a new method involving time maximum intensity projection (t-MIP) postprocessed from dynamic computed tomographic angiography (dyn-CTA) in diagnosing peripheral arterial disease (PAD).

Methods

A population of 34 patients with known PAD was examined with a combined CTA protocol consisting of a standard CTA (s-CTA) scan of the lower extremities and a dyn-CTA scan of the calves. For each lower leg, t-MIP images consisting of the MIP₀ (sagittal MIP), MIP_+θ (45° lateral MIP), and MIP_−θ (− 45° lateral MIP) were automatically generated from dyn-CTA. An objective evaluation of the vascular CT attenuation of the best enhancement phase of dyn-CTA and t-MIP was measured; a subjective evaluation of vessel stenosis and occlusion was performed, assigning a score for t-MIP and s-CTA. The CT attenuation of t-MIP and dyn-CTA was compared, as were the runoff scores of t-MIP and s-CTA.

Results

The CT attenuation of t-MIP CTA of three vascular segments from 68 lower extremities was higher than that of the best enhancement phase of dyn-CTA and s-CTA, with statistically significant differences at the posterior tibial artery and fibular artery (all p < 0.05). There were strong correlations (r ≥ 0.75, p < 0.05) of the runoff scores between t-MIP and s-CTA.

Conclusions

There is potential clinical applicability of t-MIP in assisting with the diagnosis of lower leg vascular stenosis in dyn-CTA with reliable diagnostic accuracy and convenient immediacy.

Evaluation of Intracranial Vascular Status in Patients with Acute Ischemic Stroke by Time Maximum Intensity Projection CT Angiography: A Preliminary Study

RATIONALE AND OBJECTIVES

To describe the application of time maximum intensity projection CTA (t-MIP CTA) in acute ischemic stroke and compare t-MIP CTA and single-phase CTA (sCTA) in assessing collateral circulation and predicting prognosis.

MATERIALS AND METHODS

Twenty-nine acute ischemic stroke patients who underwent one-stop CT angiography (CTA)-CT perfusion scan were reviewed retrospectively. sCTA and t-MIP CTA were developed by CT perfusion scanning data. Image quality and collateral circulation were compared between the sCTA and t-MIP CTA groups. CT attenuation values, image noise, signal to noise , contrast to noise, and subjective image quality were obtained and compared between these two groups. The correlations of clinical prognosis and infarct volume with collateral status on t-MIP CTA and sCTA were analyzed, separately. Receiver operating characteristic curve was used to reveal the sensitivity and specificity of t-MIP CTA and sCTA in predicting outcome.

RESULTS

All images exhibited good quality for diagnosis. In objective evaluation, the noise level of t-MIP CTA was significantly lower than that of sCTA (p < 0.001). Vascular attenuation (signal to noise and contrast to noise) of t-MIP were higher than those of sCTA (all, p < 0.001). The collateral status on t-MIP CTA and sCTA were both negatively correlated with modified Rankin Scale scores (t-MIP CTA, r = -0.709, p < 0.001; sCTA, r = -0.551, p = 0.024) and the final infarction volume (t-MIP CTA, r = -0.716, p = 0.001; sCTA, r = -0.629, p = 0.003). t-MIP CTA was better for predicting prognosis (AUC, 0.956; sensitivity, 0.917; specificity, 0.941; p < 0.001) than sCTA (AUC, 0.824; sensitivity, 0.500; specificity, 0.941; p = 0.003).

CONCLUSION

In comparison with sCTA, t-MIP images showed higher image quality of intracranial vascularity and MIP could reveal vascular occlusion and evaluate collateral circulation more accurately. It was speculated that t-MIP could predict the prognosis more precisely.