Multidetector Computed Tomography Perfusion Research Articles

Flat-panel Detector Perfusion Imaging and Conventional Multidetector Perfusion Imaging in Patients with Acute Ischemic Stroke : A Comparative Study.

Flat-panel detector computed tomography (FDCT) is increasingly used in (neuro)interventional angiography suites. This study aimed to compare FDCT perfusion (FDCTP) with conventional multidetector computed tomography perfusion (MDCTP) in patients with acute ischemic stroke. In this study, 19 patients with large vessel occlusion in the anterior circulation who had undergone mechanical thrombectomy, baseline MDCTP and pre-interventional FDCTP were included. Hypoperfused tissue volumes were manually segmented on time to maximum (Tmax) and time to peak (TTP) maps based on the maximum visible extent. Absolute and relative thresholds were applied to the maximum visible extent on Tmax and relative cerebral blood flow (rCBF) maps to delineate penumbra volumes and volumes with ahigh likelihood of irreversible infarcted tissue ("core"). Standard comparative metrics were used to evaluate the performance of FDCTP. Strong correlations and robust agreement were found between manually segmented volumes on MDCTP and FDCTP Tmax maps (r = 0.85, 95% CI 0.65-0.94, p < 0.001; ICC = 0.85, 95% CI 0.69-0.94) and TTP maps (r = 0.91, 95% CI 0.78-0.97, p < 0.001; ICC = 0.90, 95% CI 0.78-0.96); however, direct quantitative comparisons using thresholding showed lower correlations and weaker agreement (MDCTP versus FDCTP Tmax 6 s: r = 0.35, 95% CI -0.13-0.69, p = 0.15; ICC = 0.32, 95% CI 0.07-0.75). Normalization techniques improved results for Tmax maps (r = 0.78, 95% CI 0.50-0.91, p < 0.001; ICC = 0.77, 95% CI 0.55-0.91). Bland-Altman analyses indicated aslight systematic underestimation of FDCTP Tmax maximum visible extent volumes and slight overestimation of FDCTP TTP maximum visible extent volumes compared to MDCTP. FDCTP and MDCTP provide qualitatively comparable volumetric results on Tmax and TTP maps; however, direct quantitative measurements of infarct core and hypoperfused tissue volumes showed lower correlations and agreement.

Multidetector Computed Tomography Perfusion in Head and Neck Squamous Cell Carcinomas: Evaluation of a Dose Reduction Strategy.

Background Computed tomography perfusion (CTp), a useful technique in oncology, is not widely utilized due to the high radiation dose delivered from it. It involves scanning the region of interest every second for 50 seconds following intravenous contrast administration. Doubling sampling interval (SI) to 2 seconds will half the radiation dose, but may impact its effectiveness, which needs to be evaluated. Objectives To evaluate a dose reduction strategy in CTp by determining agreement between standard dose (SD) CTp (acquisition with SI 1 second) and low-dose CTp techniques with SI of 2 seconds (achieved either by reconstruction only or true low-dose acquisition). Materials and methods This cross-sectional study was conducted on histopathology-proven head and neck squamous cell carcinoma (HNSCC) patients who underwent CTp on 64 slice multidetector CT. A total of 56 patients had SD and 24 patients underwent true low dose (LD) acquisition. SD data were also reconstructed at SI 2 seconds to obtain a dataset simulating low dose (low-dose reconstruction [LDr]). Paired t -test was applied to compare CTp in SD and LDr groups and the Bland-Altman plot drawn to calculate 95% confidence limit of agreement. The Kolmogorov-Smirnov test compared CTp parameters for LDr and LD groups. Results There was no statistical difference in CTp parameters (except blood flow in malignant) in SD and LDr groups for both malignant and normal tissues. CTp of malignant tissue was not statistically different in LDr and LD groups but the radiation dose was half in the LD group. Conclusion Reduction of radiation dose to half achieved by doubling the SI does not affect the CTp parameters significantly. So LD acquisitions will increase the use of CTp in HNSCC.

Assessment of regional cerebral blood flow using dual energy multi detector computed tomography perfusion in patients of depression

Background: Major depressive disorder (MDD) involves a wide variety of psychobiological syndromes with the central characteristics of depressed mood and/or lack of interest associated with cognitive and somatic conditions, resulting in severe deterioration of function. Established correlation between depression and Regional cerebral hypoperfusion in specific areas by several SPECT studies. Aimed to assess changes In Regional Cerebral Blood Flow by CT Perfusion In patients of Depression. Material and Method: This prospective follow-up study conducted for duration of 18 months at Department of Radiodiagnosis, Era’s Lucknow Medical University, and Lucknow. Included all the patients aged between 18-40ys with newly diagnosed major depression fulfilling the ICD-10 criteria. Selected patients to undergo rCBF assessment before and after treatment by SIEMENS Somatom Force 384 Slice MDCT. The depression score was measured using questionnaire based with HAMD. Result: Total of 40 patients who met the inclusion criteria were included in present study after obtaining the informed consent from all. Majority of the patients were in age group of 18-30yrs of age. Majority of the patients were female than male. The depression score (HAMD) was significantly reduced at the 2nd visit (14.01±1.63) compared to the 1st visit (16.12±2.10). There was a significant improvement in the mean cerebral blood flow at 2nd visit compared to the 1st visit in various regions included as ACA, MCA and PCA of right and left side. Conclusion: The patients with depression are characterized by a wide range of cerebral blood flow impairments and there appear to be more prominent changes. The 384 slice MDCT appears to be a potentially useful tool for measuring rCBF, with advantages over existing instruments. This technique could be employed in psychiatric settings for biomarker, diagnostic and treatment response purposes.

Transmural myocardial perfusion gradients in relation to coronary artery stenoses severity assessed by cardiac multidetector computed tomography.

To assess the relationship between epicardial coronary artery stenosis severity and the corresponding regional transmural perfusion at rest and during adenosine stress, using multidetector computed tomography (MDCT). We evaluated the relationship between the severity of coronary artery diameter stenosis assessed by MDCT angiography and semi-quantitative myocardial MDCT perfusion in 200 symptomatic patients. The perfusion index (PI=mean myocardial attenuation density/mean left ventricular lumen attenuation density) at rest and during adenosine stress, the myocardial perfusion reserve (MPR=stress-PI/rest-PI), and the transmural perfusion ratio (TPR=subendocardium/subepicardium) were calculated. A coronary artery stenosis ≥50% was present in 49 patients (25%). Rest-PI and rest-TPR values were similar in patients with and without a coronary artery stenosis ≥50%, whereas stress-PI, stress-TPR and MPR were significantly reduced in patients with a stenosis ≥50% (p<0.001, p<0.0001 and p=0.02, respectively). Subendocardial PI was significantly higher than subepicardial PI at rest and during stress for patients without a significant stenosis, whereas this difference was blurred during stress in patients with ≥50% stenosis. In a broad spectrum of stenosis severity groups, TPR at rest remained unchanged until the group of patients with total occlusions, whereas TPR during stress decreased progressively when a threshold of 50% was superseded. In this study we establish the relationship between semi-quantitative perfusion measurements by MDCT and severity of coronary artery stenoses and find the transmural myocardial perfusion ratio to be a potential strong functional index of the hemodynamic significance of coronary artery atherosclerotic lesions.

Incremental value of an integrated adenosine stress-rest MDCT perfusion protocol for detection of obstructive coronary artery disease

Preliminary studies have shown the potential of myocardial computed tomography perfusion (CTP) analysis for ischemia detection in both animals and humans. To provide validation data on stress-rest CTP protocols as additive tools to improve the accuracy of multidetector computed tomography (MDCT) for coronary artery disease (CAD) in symptomatic patients. Ninety symptomatic patients with suspected CAD (62 ± 8 years, 66% males) underwent both MDCT and invasive coronary angiography (XA). The MDCT protocol included a prospective calcium score acquisition, a helical acquisition with retrospective gating during infusion of adenosine (140 μg/kg/min) and a prospective scan for computed tomography angiography (CTA) at rest (total effective radiation dose: 5.1 ± 0.8 mSv). Significant and higher-grade CADs were defined by the presence of ≥50% or ≥70% stenosis in at least one coronary artery, as evaluated by quantitative coronary angiography (QCA) using XA images. On a patient-based model, CTA sensitivity, specificity, and positive (PPV) and negative predictive values (NPV) to detect ≥50% or ≥70% stenosis were 98%, 71%, 80%, and 97% (global accuracy 86%) and 100%, 60%, 64%, and 100% (accuracy 77%), respectively. An integrative approach of CTA and CTP results had the best performance for detection of CAD with sensitivity of 83%, specificity of 98%, PPV of 98%, and NPV of 84% (accuracy 84%) for detection of 50% stenosis and 97%, 90%, 88%, and 98% (accuracy 93%), respectively, for the 70% threshold. The integration of results had the best overall performance in all scenarios but was particularly advantageous in the prediction of higher-grade CAD, with an area under the curve of 0.93, compared with 0.80 for isolated CTA and0.82 for CTP and in patients with severe calcifications (sensitivity 92%, specificity 87%, overall accuracy of 90%). The integration of functional and morphological data using CTA and CTP improved MDCT accuracy for detection of clinically relevant CAD at both thresholds of 50% and 70% in this intermediate to high pretest probability population.

Quantitative Analysis of First-Pass Contrast-Enhanced Myocardial Perfusion Multidetector CT Using a Patlak Plot Method and Extraction Fraction Correction During Adenosine Stress

The purpose of this study was to develop a quantitative method for myocardial blood flow (MBF) measurement that can be used to derive accurate myocardial perfusion measurements from dynamic multidetector computed tomography (MDCT) images by using a compartment model for calculating the first-order transfer constant ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) with correction for the capillary transit extraction fraction ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> ). Six canine models of left anterior descending (LAD) artery stenosis were prepared and underwent first-pass contrast-enhanced MDCT perfusion imaging during adenosine infusion (0.14-0.21 mg/kg/min). <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , which is the first-order transfer constant from left ventricular (LV) blood to myocardium, was measured using the Patlak plot method applied to time-attenuation curve data of the LV blood pool and myocardium. The results were compared against microsphere MBF measurements, and the extraction fraction of contrast agent was calculated. <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> is related to the regional MBF as <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">EF</i> , <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> =(1- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">exp</i> (- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PS</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> )), where <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PS</i> is the permeability-surface area product and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> is myocardial flow. Based on the above relationship, a look-up table from <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> to MBF can be generated and Patlak plot-derived <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> values can be converted to the calculated MBF. The calculated MBF and microsphere MBF showed a strong linear association. The extraction fraction in dogs as a function of flow ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> ) was <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> =(1- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">exp</i> (-(0.2532 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> +0.7871)/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> )) . Regional MBF can be measured accurately using the Patlak plot method based on a compartment model and look-up table with extraction fraction correction from <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> to MBF.

Volumetric quantification of myocardial perfusion using analysis of multi-detector computed tomography 3D datasets: comparison with nuclear perfusion imaging

Although the ability of multi-detector computed tomography (MDCT) to detect perfusion abnormalities associated with acute and chronic myocardial infarction (MI) has been demonstrated, this methodology is based on visual interpretation of selected 2D slices. We sought to develop a new technique for quantitative volumetric analysis of myocardial perfusion from 3D datasets and test it against resting nuclear myocardial perfusion imaging (NMPI) reference. We studied 44 patients undergoing CTCA: a control group of 15 patients and a study group of 29 patients. MDCT datasets acquired for CTCA were analyzed using custom software designed to: (1) generate bull's eye display of myocardial perfusion and (2) calculate a quantitative index of extent and severity of perfusion abnormality, Q(H), for 16 volumetric myocardial segments. Visual interpretation of MDCT-derived bull's eyes was compared with rest NMPI scores using kappa statistics of agreement on a coronary territory and patient basis. Quantitative MDCT perfusion data were correlated with rest NMPI summed scores and used for objective detection of perfusion defects. Visual analysis of MDCT-derived bull's eyes accurately detected perfusion defects in agreement with NMPI (kappa = 0.70 by territory; 0.79 by patient). Quantitative data were in good agreement with NMPI, as reflected by: (1) correlation of 0.87 (territory) and 0.84 (patient) between summed Q(H) and NMPI scores, (2) area under ROC curve 0.87 with sensitivity of 0.79-0.92, specificity 0.83-0.91, and accuracy 0.83-0.89 for objective detection of abnormalities. Our new technique for volumetric analysis of 3D MDCT images allows accurate objective detection of perfusion defects. This perfusion information can be obtained without additional radiation or contrast load, and may aid in elucidating the significance of coronary lesions.

Usefulness of Routine Use of Multidetector Coronary Computed Tomography in the “Fast Track” Evaluation of Patients With Acute Chest Pain

Recently published American Heart Association/American College of Cardiology guidelines suggest that multidetector computed tomography (MDCT) may be appropriate for investigating acute chest pain (ACP). Only a few small studies have evaluated the use of MDCT in ACP, where it was not part of routine investigation. We sought to evaluate the routine use of MDCT in a large cohort of patients presenting with ACP in a real-world setting. We studied 785 consecutive patients with ACP who underwent evaluation by MDCT or myocardial perfusion scintigraphy after an observation period of > or = 12 hours. Patients with findings suggestive of significant coronary artery disease (CAD) were referred to coronary angiography. Forty-two patients were hospitalized due to evidence of myocardial ischemia and 44 patients were discharged after the observation period. Of the remaining 699 patients, 340 underwent MDCT and 359 myocardial perfusion scintigraphy. In 22 patients (7%) multidetector computed tomogram showed significant CAD and in 32 (9%) patients myocardial perfusion scintigram showed significant ischemia. Significant CAD was confirmed by coronary angiography in 65% and 60%, respectively. Multidetector computed tomogram was nondiagnostic in 31 patients (9%). Extracardiac findings that might be related to ACP and/or necessitated further investigation were demonstrated by multidetector computed tomogram in 71 patients (21%). During 3-month follow-up, 1 patient (0.3%) with negative multidetector computed tomographic and 9 (3%) with negative myocardial perfusion scintigraphic findings developed an acute coronary syndrome or died. Rehospitalization, due to recurrent chest pain, occurred in 9 patients (3.3%) and 21 patients (7.2%), respectively. In conclusion, MDCT could be an appropriate alternative to traditional noninvasive techniques for investigating ACP.

Combined Assessment of Coronary Anatomy and Myocardial Perfusion Using Multidetector Computed Tomography for the Evaluation of Coronary Artery Disease

Multidetector computed tomography (MDCT) is increasingly used as an alternative to invasive coronary angiography. Although computed tomographic coronary angiography (CTCA) has been validated against invasive coronary angiography and nuclear myocardial perfusion imaging, the potential of MDCT to evaluate perfusion has not been fully explored. We sought to (1) develop a new technique for quantitative assessment of myocardial enhancement based on analysis of MDCT images acquired for CTCA, (2) identify the underlying causes of myocardial hypoenhancement detected by MDCT, and (3) determine the added diagnostic value of the MDCT perfusion index when combined with CTCA. We studied 84 patients undergoing clinical CTCA (64 patients with invasive coronary angiogram and a control group of 20 patients). MDCT perfusion index was calculated from x-ray attenuation measured in 16 myocardial segments. Hypoenhancement was automatically detected using comparisons with the normal range obtained in the control group, and its added value was determined against invasive coronary angiographic findings combined with known previous myocardial infarction. Myocardial hypoenhancement was detected in 29 of 64 patients in 47 vascular territories, of which 36 (77%) were abnormal by the reference technique. Of these 36 abnormalities, 10 (28%) were associated with previous myocardial infarction, whereas 26 (72%) corresponded to significant coronary stenosis. The addition of MDCT perfusion index to CTCA improved its diagnostic accuracy (sensitivity 0.87 to 0.96, accuracy 0.84 to 0.88, despite a decrease in specificity 0.79 to 0.68). In conclusion, myocardial hypoenhancement is a potentially valuable addition to MDCT evaluation of coronary artery disease without additional cost in radiation dose or contrast load.

Abstract 4177: Quantitative Evaluation of Regional Myocardial Blood Flow Using Multi-detector Row Computed Tomography in Pre- and Post- Coronary Artery Bypass Grafting Patients; Assessment with Regional Left Ventricular Function

Introduction: The advent of high resolution multidetector computed tomography (MDCT) created the potential to quantify myocardial blood flow (MBF) reduction. The effect in regional MBF produced by coronary artery bypass grafting has not been quantitatively evaluated. The purpose of this study was to test the hypothesis that adenosine stress/rest MDCT can detect ischemia by measuring MBF differences in pre- versus post-CABG patients. Methods: Ninety regional areas in 10 patients (median age 71; 65–79, 7 males), scheduled for CABG at our institution, were studied. Each patient underwent adenosine stress 64-slice MDCT perfusion imaging in both pre- and postoperative period. Myocardial blood flow was calculated with Patlak plots analysis. Regional left ventricular function (LVF) was assessed by Echocardiography. Results: Preoperative mean MBF in ischemic and non-ischemic areas was 0.76±0.49 (ml/g/min) and 2.15±0.66, respectively (p&lt;0.05). Postoperative MBF increased to 1.40±0.77 (ml/g/min) in ischemic areas (p&lt;0.05), though the non-ischemic area showed no differences. The degree of ischemia on MDCT was correlated to change in regional LVF. Postoperative assessment revealed the improved regional LVF that was correlated with the increase in regional MBF. Conclusions: The regional MBF can be quantitatively assessed by adenosine stress 64-slice MDCT perfusion imaging. This technique provides quantitative information about regional MBF in pre- and post- CABG patients, which may predict the regional LVF recovery after CABG.

Differences in episode-based care costs for multidetector computed tomographic coronary angiography versus myocardial perfusion imaging for the diagnosis of coronary artery disease

Background: Multidetector computed tomography (MDCT) is a novel method for diagnosis and prognosis of coronary artery disease (CAD). The opportunity costs that favour MDCT over other CAD diagnostic methods is currently unknown.Methods: This study used an episodes of care cost model based on epidemiologic and economic data evaluating individuals without known CAD undergoing MDCT or myocardial perfusion scintigraphy (MPS). It was a multicenter retrospective database review of medical and pharmacy-related claims linked by episodes of care from 2002 to 2005. CAD-related episodes of care costs were examined 1-year downstream for patients after initial MDCT that were matched to patients who underwent MPS.Results: After adjustment for patient factors, 1-year total CAD-related episodes of care costs for MDCT were 16.4% lower than MPS, by an average of $682 (95% confidence interval $14, $1,350) per patient. While costs per CAD-related episode were similar between MDCT and MPS groups ($4,284 vs. $4,277, p=0.08).Conclusions: Patients without known CAD who undergo MDCT as an initial diagnostic test, compared to MPS, incurred fewer CAD-related episodes of care and lower overall CAD-related costs.

Abstract 2547: Quantification of Myocardial Perfusion in Patients Using 256-Row Multidetector Computed Tomography: Evaluation of Endocardial vs. Epicardial Blood Flow

Introduction: The advent of 256x0.5 mm high resolution multidetector computed tomography (MDCT) created the potential to quantify subendocardial myocardial blood flow (MBF) reduction, the hallmark of ischemia. The purpose of this study was to test the hypothesis that adenosine stress / rest 256x0.5mm MDCT can detect ischemia by measuring differences in subendo-cardial versus subepicardial MBF. Methods: Nineteen patients with abnormal SPECT perfusion studies underwent adenosine (140μg/kg/min) stress 256x0.5mm MDCT perfusion imaging (CTP): 120kV, 100mAs, 3 gantry rotations at 0.5 secs, followed by rest 256x0.5mm MDCT angiography (CTA): 120kV, 175mAs, 3 gantry rotations at 0.5 secs. CT perfusion images were reconstructed in the short axis with a 3 mm slice thickness. Endocardial and epicardial borders were defined, myocardium was sectored according to the standard 17 segment model, and divided circumferentially into endocardial and epicardial layers. The transmural perfusion ratio (TPR) was calculated by dividing the endocardial attenuation density (AD) by the epicardial AD in each sector. Ischemia was defined as TPR &lt;0.8 in more than one sector. The TPR results were compared to the presence or absence of stenoses ≥50% on CTA and perfusion deficits on SPECT. Results: Mean TPR in abnormal and normal sectors was 0.71±0.05 and 1.01±0.06, respectively (p&lt;0.01). Mean number of abnormal sectors for patients with no stenoses, 1-vessel, and multi-vessel disease were 1.6, 2.5, and 6.3; respectively (p&lt;0.05). The sensitivity and specificity of TPR for detecting a stenosis ≥50% severity was 62% and 86% compared with 62% and 71% for SPECT (NS). When defining territorial ischemia as a SPECT perfusion abnormality plus a stenosis ≥50%, the sensitivity, specificity, positive and negative predictive values were 75%, 95%, 75%, and 95% for combined CTA/CTP imaging, respectively. Conclusions: The transmural perfusion ratio measured from 256x0.5mm MDCT perfusion images can detect the presence of obstructive atherosclerosis with similar accuracy compared with SPECT imaging. The combination of 256x0.5mm MDCT angiography and perfusion imaging may avoid the high false positive rate seen with SPECT imaging alone as well as improve its prediction of territorial ischemia.