scholarly journals The Efficacy of Calculation of Mean Transit Time without Using Arterial Input Function : A Trial of Classification of Perfusion Reserve Capacity using Perfusion MRI

2003 ◽  
Vol 12 (10) ◽  
pp. 676-684
Author(s):  
Masahiro Furuichi ◽  
Yuzo Araki ◽  
Hiroaki Nokura ◽  
Ayumi Okumura ◽  
Shinichi Yoshimura ◽  
...  
Keyword(s):  
Transit Time ◽  
Arterial Input Function ◽  
Mean Transit Time ◽  
Input Function ◽  
Perfusion Mri ◽  
Reserve Capacity ◽  
Perfusion Reserve

scholarly journals Clinical and Radiological Correlates of Reduced CBF Measured Using MRI

Stroke ◽  
2001 ◽  
Vol 32 (suppl_1) ◽  
pp. 317-318
Author(s):  
Vincent N Thijs ◽  
Tobias Neumann-Haefelin ◽  
Michael E Moseley ◽  
Michael P Marks ◽  
Gregory W Albers
Keyword(s):  
Symptom Onset ◽  
Cerebral Blood Volume ◽  
Arterial Input Function ◽  
Mean Transit Time ◽  
Input Function ◽  
Lesion Volume ◽  
Time Curve ◽  
Measured Concentration ◽  
Ischemic Lesion ◽  
Adc Values

11 Background and purpose Methods for determining CBF using IV bolus tracking MRI have recently become available. Reduced apparent diffusion coefficient (ADC) values of brain tissue are associated with reductions in regional cerebral blood flow (rCBF). We studied the clinical and radiological features of patients with severe reductions of rCBF on MRI and analysed the relationship between reduced rCBF and ADC. Methods We studied patients with non-lacunar acute ischemic stroke in whom PWI and DWI MRI were performed within 7 hours after symptom onset. A PWI>DWI mismatch of >20% was required. Maps of rCBF, cerebral blood volume (rCBV) and mean transit time (rMTT) were generated after deconvoluting the measured concentration-time curve with the arterial input function using singular value decomposition. The ischemic lesion was outlined on the MTT map and the region of interest (ROI) transferred to the rCBF and rCBV map. ADC-maps were calculated. ADC lesions were defined as regions with ADC values ≤ 550 μm m2/sec. We compared the characteristics of patients with ischemic lesions that had a relative CBF of <50% to the contralateral hemisphere to patients with lesions that had relative CBF of >50%. Characteristics analysed included age, time to MRI, baseline NIHSS, mean ADC, DWI lesion volume, PWI lesion volume and absolute mismatch volume. Results Fifteen patients with an initial PWI>DWI mismatch of >20% were included. Ten had lesions with rCBF of >50% (median 60%) and five patients had rCBF of <50% (median 27.7%). Patients with rCBF <50% had lower ADC values (median 431 μmm2/sec versus 506 μ mm2/sec, p=0.028), larger DWI volumes (median 75.6 cm 3 versus 8.6 cm 3 , p=0.001) and larger PWI lesions as defined by the MTT volume (median 193 cm 3 versus 69 cm 3 , p=0.028) and more severe baseline NIHSS scores (median 18 versus 9, p=0.019). The rMTT and rCBV of the lesions were similar in both groups, as were the age, the absolute mismatch volume and the time from symptom onset to MRI. Conclusion These data indicate that ischemic lesions with severe CBF reductions, measured with new MRI techniques, are associated with a lower mean ADC, larger DWI and PWI lesion volumes and a higher NIHSS score.

scholarly journals Optimal Scaling Approaches for Perfusion MRI with Distorted Arterial Input Function (AIF) in Patients with Ischemic Stroke

2022 ◽  
Vol 12 (1) ◽  
pp. 77
Author(s):  
Sukhdeep Singh Bal ◽  
Fan Pei Gloria Yang ◽  
Yueh-Feng Sung ◽  
Ke Chen ◽  
Jiu-Haw Yin ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Arterial Input Function ◽  
Input Function ◽  
Peak Height ◽  
Perfusion Mri ◽  
Mri Imaging ◽  
Inaccurate Estimation ◽  
Parameter Values ◽  
The Brain ◽  
Accurate Quantification

Background: Diagnosis and timely treatment of ischemic stroke depends on the fast and accurate quantification of perfusion parameters. Arterial input function (AIF) describes contrast agent concentration over time as it enters the brain through the brain feeding artery. AIF is the central quantity required to estimate perfusion parameters. Inaccurate and distorted AIF, due to partial volume effects (PVE), would lead to inaccurate quantification of perfusion parameters. Methods: Fifteen patients suffering from stroke underwent perfusion MRI imaging at the Tri-Service General Hospital, Taipei. Various degrees of the PVE were induced on the AIF and subsequently corrected using rescaling methods. Results: Rescaled AIFs match the exact reference AIF curve either at peak height or at tail. Inaccurate estimation of CBF values estimated from non-rescaled AIFs increase with increasing PVE. Rescaling of the AIF using all three approaches resulted in reduced deviation of CBF values from the reference CBF values. In most cases, CBF map generated by rescaled AIF approaches show increased CBF and Tmax values on the slices in the left and right hemispheres. Conclusion: Rescaling AIF by VOF approach seems to be a robust and adaptable approach for correction of the PVE-affected multivoxel AIF. Utilizing an AIF scaling approach leads to more reasonable absolute perfusion parameter values, represented by the increased mean CBF/Tmax values and CBF/Tmax images.

scholarly journals Assessment of Renal Function Based on Dynamic Scintigraphy Parameters in the Diagnosis of Obstructive Uro/Nephropathy

2021 ◽  
Vol 10 (3) ◽  
pp. 529
Author(s):  
Paweł Cichocki ◽  
Krzysztof Filipczak ◽  
Zbigniew Adamczewski ◽  
Jacek Kuśmierek ◽  
Anna Płachcińska
Keyword(s):  
Renal Function ◽  
Transit Time ◽  
Mean Transit Time ◽  
Diagnostic Value ◽  
Normative Values ◽  
Cohen’S Kappa ◽  
Cohen's Kappa ◽  
Split Function

This study evaluates the usefulness of parameters allowing assessment of renal function in absolute values in dynamic renal scintigraphy (DRS) with 99mTc-ethylenedicysteine (99mTc-EC) uptake constant (K), mean transit time (MTT), and parenchymal transit time (PTT) in the diagnosis of obstructive uro/nephropathy. The study included 226 people: 20 healthy volunteers, for whom normative values of assessed parameters were determined, and 206 patients. Reproducibility of results obtained by two independent operators, specificity, correlation with estimated GFR (eGFR), and Cohen’s kappa were used to evaluate reliability of assessed parameters. Normative values were as follows: K ≥ 1.6, MTT ≤ 250 s, and PTT ≤ 225 s. Reproducibility of determination of K (rs = 0.99) and MTT (rs = 0.98) was significantly higher than that of PTT (rs = 0.95) (p = 0.001). Specificity was 100% for K, 81% for MTT, and 91% for PTT. Correlation of eGFR with K (rs = 0.89) was significantly higher than with PTT (rs = 0.53) and with split function (SF) (rs = 0.66) (p < 0.0001). Cohen’s kappa was κ = 0.89 for K, κ = 0.88 for MTT, and κ = 0.77 for PTT. In a group of patients where standard DRS parameters are unreliable (bilateral obstructive uro/nephropathy or single functioning kidney), the use of K (the most effective among assessed parameters) changed the classification of 23/79 kidneys (29%). K enables reproducible assessment of absolute, individual kidney function without modifying routine DRS protocol. Diagnostic value of MTT and PTT is limited.

scholarly journals Computational Fluid Dynamics Simulations of Contrast Agent Bolus Dispersion in a Coronary Bifurcation: Impact on MRI-Based Quantification of Myocardial Perfusion

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Regine Schmidt ◽  
Dirk Graafen ◽  
Stefan Weber ◽  
Laura M. Schreiber
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Myocardial Perfusion ◽  
Contrast Agent ◽  
Arterial Input Function ◽  
Myocardial Perfusion Reserve ◽  
Input Function ◽  
Coronary Bifurcation ◽  
Perfusion Reserve ◽  
Contrast Agent Bolus

Contrast-enhanced first-pass magnetic resonance imaging (MRI) in combination with a tracer kinetic model, for example, MMID4, can be used to determine myocardial blood flow (MBF) and myocardial perfusion reserve (MPR). Typically, the arterial input function (AIF) required for this methodology is estimated from the left ventricle (LV). Dispersion of the contrast agent bolus might occur between the LV and the myocardial tissue. Negligence of bolus dispersion could cause an error in MBF determination. The aim of this study was to investigate the influence of bolus dispersion in a simplified coronary bifurcation geometry including one healthy and one stenotic branch on the quantification of MBF and MPR. Computational fluid dynamics (CFD) simulations were combined with MMID4. Different inlet boundary conditions describing pulsatile and constant flows for rest and hyperemia and differing outflow conditions have been investigated. In the bifurcation region, the increase of the dispersion was smaller than inside the straight vessels. A systematic underestimation of MBF values up to −16.1% for pulsatile flow and an overestimation of MPR up to 7.5% were found. It was shown that, under the conditions considered in this study, bolus dispersion can significantly influence the results of quantitative myocardial MR-perfusion measurements.

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