[The Optimal Start Timing of Helical Scan for Coronary CT Angiography and CT Myocardial Perfusion Scan Using 64-MDCT].

PURPOSE: Ichihara et al. (Fujita Med J 2015; 1(1): 9-14) developed a method to simultaneously obtain both coronary computed tomography (CT) angiography and CT myocardial perfusion (CTP) using 64-multi detector CT (MDCT). An input-function (time enhancement curve, TEC) of the ascending aorta (Ao) and myocardial CT density are necessary to calculate absolute myocardial blood flow (ml/g/min) using a two-compartment model. Helical scan starting timing is important to capture the peak (P) of Ao time enhancement curve (TEC). The purpose is to search the optimal timing of starting helical scan to capture the P. METHODS: We performed 14 CTPs using Definition AS+ (SIEMENS). A dynamic scan at the Ao level was started at 7 s after contrast injection and helical scan was started at various trigger on bolus tracking. Definition AS+ needs 2 s (other scanner may need 4 s) for changing from a dynamic to helical scan mode. We created TECs of pulmonary artery (PA) and Ao using the fifth function fitting. We measured the time from trigger point to the P (t200, t250, t300 and tCP). RESULTS: Mean t200, t250, t300 and tCP were 9.1±1.9, 7.9±2.0, 6.6±1.9 and 3.9±1.2 s, respectively. In additional other 16 CTP studies using the cross point method, we can capture the P in all (100%) examinations. CONCLUSION: Scan starting at the cross point is best for Definition AS+, and the Ao=300 HU may be best for other scanner that needs 4 s for changing scan mode to obtain a fine input function for calculating absolute myocardial blood flow.

[Development of a Striatal and Skull Phantom for Quantitative 123I-FP-CIT SPECT].

BACKGROUND: 123Iodine-labelled N-(3-fluoropropyl) -2ß-carbomethoxy-3ß-(4-iodophenyl) nortropane (123I-FP-CIT) single photon emission computerized tomography (SPECT) images are used for differential diagnosis such as Parkinson's disease (PD). Specific binding ratio (SBR) is affected by scattering and attenuation in SPECT imaging, because gender and age lead to changes in skull density. It is necessary to clarify and correct the influence of the phantom simulating the the skull. PURPOSE: The purpose of this study was to develop phantoms that can evaluate scattering and attenuation correction. METHODS: Skull phantoms were prepared based on the measuring the results of the average computed tomography (CT) value, average skull thickness of 12 males and 16 females. 123I-FP-CIT SPECT imaging of striatal phantom was performed with these skull phantoms, which reproduced normal and PD. SPECT images, were reconstructed with scattering and attenuation correction. SBR with partial volume effect corrected (SBRact) and conventional SBR (SBRBolt) were measured and compared. RESULTS: The striatum and the skull phantoms along with 123I-FP-CIT were able to reproduce the normal accumulation and disease state of PD and further those reproduced the influence of skull density on SPECT imaging. The error rate with the true SBR, SBRact was much smaller than SBRBolt. CONCLUSION: The effect on SBR could be corrected by scattering and attenuation correction even if the skull density changes with 123I-FP-CIT on SPECT imaging. The combination of triple energy window method and CT-attenuation correction method would be the best correction method for SBRact.

Robot-assisted partial nephrectomy: Superiority over laparoscopic partial nephrectomy.

Nephron-sparing surgery has been proven to positively impact the postoperative quality of life for the treatment of small renal tumors, possibly leading to functional improvements. Laparoscopic partial nephrectomy is still one of the most demanding procedures in urological surgery. Laparoscopic partial nephrectomy sometimes results in extended warm ischemic time and severe complications, such as open conversion, postoperative hemorrhage and urine leakage. Robot-assisted partial nephrectomy exploits the advantages offered by the da Vinci Surgical System to laparoscopic partial nephrectomy, equipped with 3-D vision and a better degree in the freedom of surgical instruments. The introduction of the da Vinci Surgical System made nephron-sparing surgery, specifically robot-assisted partial nephrectomy, safe with promising results, leading to the shortening of warm ischemic time and a reduction in perioperative complications. Even for complex and challenging tumors, robotic assistance is expected to provide the benefit of minimally-invasive surgery with safe and satisfactory renal function. Warm ischemic time is the modifiable factor during robot-assisted partial nephrectomy to affect postoperative kidney function. We analyzed the predictive factors for extended warm ischemic time from our robot-assisted partial nephrectomy series. The surface area of the tumor attached to the kidney parenchyma was shown to significantly affect the extended warm ischemic time during robot-assisted partial nephrectomy. In cases with tumor-attached surface area more than 15 cm(2) , we should consider switching robot-assisted partial nephrectomy to open partial nephrectomy under cold ischemia if it is imperative. In Japan, a nationwide prospective study has been carried out to show the superiority of robot-assisted partial nephrectomy to laparoscopic partial nephrectomy in improving warm ischemic time and complications. By facilitating robotic technology, robot-assisted partial nephrectomy will be more frequently carried out as a safe, effective and minimally-invasive nephron-sparing surgery procedure.

Effect of Green Tea Extract Ingestion on Fat Oxidation during Exercise in the Menstrual Cycle: A Pilot Study.

In women, fat oxidation during exercise changes with the menstrual cycle. This study aimed to investigate the effect of green tea extract (GTE) ingestion on fat oxidation during exercise depending on the menstrual cycle phase. Ten women with regular menstrual cycles participated in this randomized, double-blind, crossover study. GTE or placebo was administered during the menstrual cycle's follicular phase (FP) and luteal phase (LP). Participants cycled for 30 min at 50% maximal workload, and a respiratory gas analysis was performed. Serum estradiol, progesterone, free fatty acid, plasma noradrenaline, blood glucose, and lactate concentrations were assessed before, during, and after the exercise. Fat oxidation, carbohydrate oxidation, and the respiratory exchange ratio (RER) were calculated using respiratory gas. Fat oxidation during the exercise was significantly higher in the FP than in the LP with the placebo (p < 0.05) but did not differ between the phases with GTE. Carbohydrate oxidation, serum-free fatty acid, plasma noradrenaline, blood glucose, and lactate concentrations were not significantly different between the phases in either trial. Our results suggest that GTE ingestion improves the decrease in fat oxidation in the LP.

Quantification of myocardial blood flow using model based analysis of first-pass perfusion MRI: extraction fraction of Gd-DTPA varies with myocardial blood flow in human myocardium.

For the absolute quantification of myocardial blood flow (MBF), Patlak plot-derived K1 need to be converted to MBF by using the relation between the extraction fraction of gadolinium contrast agent and MBF. This study was conducted to determine the relation between extraction fraction of Gd-DTPA and MBF in human heart at rest and during stress. Thirty-four patients (19 men, mean age of 66.5 ± 11.0 years) with normal coronary arteries and no myocardial infarction were retrospectively evaluated. First-pass myocardial perfusion MRI during adenosine triphosphate stress and at rest was performed using a dual bolus approach to correct for saturation of the blood signal. Myocardial K1 was quantified by Patlak plot method. Mean MBF was determined from coronary sinus flow measured by phase contrast cine MRI and left ventricle mass measured by cine MRI. The extraction fraction of Gd-DTPA was calculated as the K1 divided by the mean MBF. The extraction fraction of Gd-DTPA was 0.46 ± 0.22 at rest and 0.32 ± 0.13 during stress (P < 0.001). The relationship between extraction fraction (E) and MBF in human myocardium can be approximated as E = 1 - exp(-(0.14 × MBF + 0.56)/MBF). The current results indicate that MBF can be accurately quantified by Patlak plot method of first-pass myocardial perfusion MRI by performing a correction of extraction fraction.

[A trial of 89Sr bremsstrahlung SPECT].

OBJECTIVE: 89Sr bremsstrahlung SPECT imaging has been evaluated for detecting the more detailed whole body 89Sr distribution. METHODS: 89Sr bremsstrahlung whole body planar and merged SPECT images were acquired by using two detectors type SPECT system. Energy window A (100 keV +/- 50%) for planar imaging, and energy window A plus adjacent energy window B (300 keV +/- 50%) for SPECT imaging were set on the continuous spectrum. Those images were compared with 99mTc-H-MDP whole body planar and merged SPECT images. To verify the accumulation obtained by bremsstrahlung whole body planar and merged SPECT image, we made original phantom based on the counts of clinical study imaging. RESULTS: On 89Sr bremsstrahlung merged SPECT image, focal accumulations were recognized in the parts of 99mTc-H-MDP merged SPECT accumulation. Focal accumulations were much clearer on 89Sr bremsstrahlung merged SPECT imaging than those of whole body planar image of 89Sr bremsstrahlung. In phantom study, counts of each concentration linearly increase as acquisition time and number of rotation increase on planar and SPECT images. CONCLUSIONS: 89Sr bremsstrahlung merged SPECT imaging would be useful for detecting the more detailed whole body 89Sr distribution.

Semi-quantitative assessment optimized the grading of pulmonary aspiration on salivagram in children.

OBJECTIVE: Salivagram is one of the imaging modalities to detect pulmonary aspiration in children. This study aims to optimize the classification of pulmonary aspiration detected by salivagram with a semi-quantitative analytical method. METHODS: This is a retrospective study involving 737 patients (471 males, 266 females; aged 1 month to 8 years; mean age 5.3 months, median age 3.0 months old) with suspected pulmonary aspiration, who had salivagram done between January 2018 and June 2019. Positive cases were divided into 10 groups (Grade 1, R2, L2, R2L2, R3, L3, R3L2, R2L3, R3L3, and 4) according to the scintigraphic findings. Aspiration index was determined as the ratio of the count in the respiratory tract to the total count in the image field of view and compared among different groups using the receiver operating characteristics (ROC) curve analysis. RESULTS: A total of 180 cases had positive scintigraphic findings of various grades of aspiration (24.4%, 180/737). There is a high consistency among the two independent nuclear medicine physicians involved in the study, in determining both the disease gradings (κ = 0.919;95% CI: 0.915-0.923) and aspiration index (ICC = 0.994;95% CI: 0.993-0.996). There is no significant difference (p > 0.05) in aspiration index among the gradings in "mild" group (grade 1, R2, L2, L2R2), and "moderate" group (grade R3, R3L2, R3L3). After dividing the different grades into "mild", "moderate" and "severe" groups, the aspiration index of "mild" group is 4.40 ± 2.01, that of "moderate" group is 16.43 ± 8.20, and that of "severe" group is 46.94 ± 14.81. Difference in groups was statistically significant (p < 0.0001). In ROC curve analysis, AUC of "mild" and "moderate" groups is 0.970 and that of "moderate" and "severe" groups is 0.943; the cut-off value with highest diagnostic efficiency is 6.75 between "mild" and "moderate" groups and 38.00 between "moderate" and "severe" groups. CONCLUSIONS: We introduced a semi-quantitative analytical method in pulmonary aspiration on salivagram, to optimize and supplement to the current classification of pulmonary aspiration.

A method for reconstructing the arterial input function during helical CT: implications for myocardial perfusion distribution imaging.

PURPOSE: To determine if a multidetector computed tomographic (CT) image acquisition and analysis method can enable accurate measurement of the arterial input function (AIF) during first-pass adenosine stress helical multidetector CT angiography and to test the effect of using this method on the semiquantitative assessment of myocardial perfusion distribution. MATERIALS AND METHODS: The animal care and use committee of Johns Hopkins University approved the use of all procedures. The AIF was reconstructed by using a combination of bolus-tracking and time-registered helical multidetector CT data. After the AIF reconstruction method was validated in healthy animals, coronary stenosis was induced in seven dogs and contrast material-enhanced multidetector CT was performed during adenosine infusion (0.14-0.21 mg per kilogram of body weight per minute). Myocardial attenuation density (AD) parameters normalized to portions of the AIF were compared with microsphere myocardial blood flow (MBF) measurements at linear regression analysis. RESULTS: There was no significant difference between the area under the curve (AUC) for dynamic multidetector CT-derived AIF (3108 + or - 1250 [standard deviation]) and that for combined bolus-tracking and time-registered multidetector helical CT-derived AIF (3086 + or - 941) (P = .90). When AIF analysis was applied to helical multidetector CT myocardial perfusion measurements, the correlation between MBF and mean myocardial AD normalized to the AUC for the entire AIF was significant (R(2) = 0.82, P <.001). Myocardial AD normalized to the AUC for the AIF measured during helical multidetector CT correlated best with MBF (R(2) = 0.86, P <.001). CONCLUSION: The combination of bolus tracking and time-registered helical imaging enables reconstruction of the AIF during multidetector CT perfusion imaging. The helical CT AIF can be used to improve the semiquantitative assessment of myocardial perfusion distribution.

Measurement of effective renal plasma flow using model analysis of dynamic CT in the preoperative evaluation of the renal transplant donors.

OBJECTIVES: Renal scintigraphy is widely used to evaluate residual function of a transplanted kidney from the donor. Dynamic computed tomography (CT) imaging can evaluate both kidney morphology and regional renal function. The aim of this study was to develop an imaging protocol and a calculation method using dynamic CT for assessing the effective renal plasma flow (ERPF) by model analysis, and to evaluate the validity of the obtained ERPF values. METHODS: Preoperative dynamic CT examination with a low radiation dose exposure system was performed for 25 renal transplant donors, and ERPF was calculated from the obtained images (CT-ERPF). To calculate CT-ERPF, we set the region of interest (ROI) in the renal cortex using automatic ROI-setting software developed in our laboratory. We compared the processing time with automatic and manual ROI settings. To evaluate the validity of CT-ERPF, we examined the correlation of age with CT-ERPF and compared with reported ERPF values. We also compared the uptake rates of technetium-99m-dimercaptosuccinic acid and CT-ERPF in terms of the right-to-left ratio. RESULTS: There was good agreement of CT-ERPF assessed using automatic and manual ROIs. CT-ERPF was negatively correlated with age and showed values below the reference ERPF range in 21 cases. The right-to-left ratio of CT-ERPF showed a significant correlation with that of technetium-99m-dimercaptosuccinic acid. CONCLUSIONS: Using our method, CT-ERPF was a useful indicator for preoperative evaluation of donor's renal function.

Quantitative analysis of first-pass contrast-enhanced myocardial perfusion MRI using a Patlak plot method and blood saturation correction.

The objectives of this study were to develop a method for quantifying myocardial K(1) and blood flow (MBF) with minimal operator interaction by using a Patlak plot method and to compare the MBF obtained by perfusion MRI with that from coronary sinus blood flow in the resting state. A method that can correct for the nonlinearity of the blood time-signal intensity curve on perfusion MR images was developed. Myocardial perfusion MR images were acquired with a saturation-recovery balanced turbo field-echo sequence in 10 patients. Coronary sinus blood flow was determined by phase-contrast cine MRI, and the average MBF was calculated as coronary sinus blood flow divided by left ventricular (LV) mass obtained by cine MRI. Patlak plot analysis was performed using the saturation-corrected blood time-signal intensity curve as an input function and the regional myocardial time-signal intensity curve as an output function. The mean MBF obtained by perfusion MRI was 86 +/- 25 ml/min/100 g, showing good agreement with MBF calculated from coronary sinus blood flow (89 +/- 30 ml/min/100 g, r = 0.74). The mean coefficient of variation for measuring regional MBF in 16 LV myocardial segments was 0.11. The current method using Patlak plot permits quantification of MBF with operator interaction limited to tracing the LV wall contours, registration, and time delays.

Predicting organ carotenoids levels from analysis of plasma could lead to errors: A study in cynomolgus monkeys.

Carotenoids are phytochemicals with strong antioxidant activity against reactive oxygen species that are widely distributed in fruits and vegetables. The beneficial effects of carotenoids on human health have attracted considerable attention. The plasma carotenoid profile in humans is generally recognized to reflect the dietary carotenoid composition. Although carotenoid profile in plasma is believed to correlate well with that in other tissues, the data for tissue accumulation of carotenoids in humans is very limited and poorly understood. In order to test the hypothesis that blood carotenoids reflect tissue accumulation of dietary carotenoids, the cynomolgus monkey was used as a model to determine it's suitable for extrapolation of data on tissue accumulation of carotenoids to humans. Herein, plasma carotenoids were measured in cynomolgus monkeys given a dietary mixture of carotenoids. The findings indicate that cynomolgus monkeys and humans are similar with regard to preferential accumulation of ß-cryptoxanthin in the blood and brain. These results suggested that cynomolgus monkeys could be used to collect data on tissue accumulation of carotenoids for extrapolation to humans. The tissue accumulation of carotenoids in other tissues of cynomolgus monkeys that have not yet been evaluated in humans were also investigated, revealing marked differences in carotenoid levels and composition among plasma and various monkey tissues. These results suggest that accumulation of carotenoids in plasma does not reflect necessarily that in tissues, so that predicting the tissue accumulation of carotenoids from plasma carotenoid levels and profiles alone could lead to errors.

Clinical utility of the normal database of 123I-iodoamphetamine brain perfusion single photon emission computed tomography for statistical analysis using computed tomography-based attenuation correction: a multicenter study.

OBJECTIVES: We have established a common normal database (NDB) with applicability in multicenter settings for the statistical analysis of brain perfusion single photon emission computed tomography (SPECT) with triple energy window scatter correction, computed tomography-based attenuation correction (CTAC), and spatial resolution compensation. This study aimed to compare the CTAC normal database (CTAC-NDB) with conventional normal databases for the statistical analysis of 123I-iodoamphetamine (123I-IMP) brain perfusion SPECT at three institutions and to assess the clinical efficiency of CTAC-NDB. METHODS: We recruited 45 patients (26 men and 19 women; mean age, 74.2 ± 3.9 years; Mini-Mental State Examination score, 19.8 ± 6.1) with Alzheimer's disease (AD, n = 26), dementia with Lewy bodies (DLB, n = 9), and mild cognitive impairment (n = 10) from three institutions. Three-dimensional stereotactic surface projection (3D-SSP) technique was used to analyze data obtained from the 123I-IMP brain perfusion SPECT images compared with both CTAC-NDB and conventional NDB. We visually assessed each 3D-SSP z score map to determine the changes in specific findings, such as AD/DLB pattern. Furthermore, the stereotactic extraction estimation analysis software was used to measure the regional z score severity and extent as a semiquantitative assessment. RESULTS: In the visual assessment, all cases exhibited clearer findings with CTAC-NDB than with conventional NDB in the parietotemporal association cortex as well as in the inferior temporal, frontal, and lateral occipital cortices. Contrarily, the findings from the medial cerebral regions, including the precuneus and the posterior cingulate, became indistinct in 71% of the cases and remained unchanged in 25% of the cases. In the semiquantitative analysis, a similar tendency was observed in the mean z score in the three institutions included in the study. CONCLUSION: Using the CTAC-NDB, the findings in the vicinity of the cranium became increasingly clear, whereas those in the medial surface of the brain became less defined or remained unchanged. These findings were confirmed via a semiquantitative analysis. Moreover, similar changes in the reduction pattern were observed in the three institutions. Therefore, the new database with CTAC might be applicable in other institutions. Data collected in this study may serve as a CTAC-NDB.

Effects of Dietary Paprika Xanthophylls on Ultraviolet Light-Induced Skin Damage: A Double-Blind Placebo-Controlled Study.

Generation of singlet oxygen by solar ultraviolet (UV) radiation causes acute inflammatory responses in the skin. Accumulation of singlet-oxygen-quenching antioxidants in the skin can suppress this photo-oxidative stress. This study evaluated the effect of dietary xanthophylls from red paprika fruit extract on UV-induced skin damage. A randomised double-blind placebo-controlled parallel group comparison study involving 46 healthy volunteers was performed. The minimal erythema dose (MED) of each individual was determined prior to the study. A capsule containing paprika xanthophylls (9 mg) or a placebo was administered daily for 5 weeks. The MED, minimal tanning dose (MTD), skin physiology parameters (skin color, hydration, and barrier function), and facial skin physiology parameters were evaluated at weeks 0, 2, and 4. The MED of the verum group at 2 and 4 weeks after administration was significantly higher than that of the placebo group. At 4 weeks, the suppression of UV-induced skin darkening by the verum diet was significantly greater than that of the placebo. There were no significant differences in facial skin parameters between the verum and placebo groups. Our results indicate the efficacy of dietary paprika xanthophylls in suppression of UV-induced skin damage.

Effect of Oral Paprika Xanthophyll Intake on Abdominal Fat in Healthy Overweight Humans: A Randomized, Double-blind, Placebo-controlled Study.

PURPOSE: Xanthophylls that exist in various vegetables and fruits have beneficial actions, such as antioxidant activity and an anti-metabolic syndrome effect, and daily intake of xanthophylls could play an important role in preventing lifestyle-related diseases. We investigated whether intake of xanthophylls from red paprika could decrease the abdominal fat area in the healthy overweight volunteers with a body mass index (BMI) ranging from 25 to < 30 kg/m2. METHODS: In a randomized, double-blind, placebo-controlled, parallel-group study, 100 healthy volunteers were assigned to oral administration of paprika xanthophyll capsules (containing 9.0 mg of paprika xanthophylls) or placebo capsules for 12 weeks. The primary endpoint was the effect of paprika xanthophyll intake on the abdominal visceral fat area (VFA) as determined by computed tomography. The secondary endpoints were as follows: 1) changes of the abdominal subcutaneous fat area (SFA), total fat area (TFA), and BMI; 2) changes of lipid metabolism parameters, glucose metabolism parameters, and other blood parameters. RESULTS: After 12 weeks, VFA was smaller in the paprika xanthophyll group than in the placebo group. In the paprika xanthophyll group, there was a significant decrease of SFA, TFA, and BMI after 12 weeks compared with baseline, and the reduction of SFA, TFA, and BMI was significantly greater in the paprika xanthophyll group than in the placebo group. Moreover, total cholesterol and low-density lipoprotein cholesterol decreased significantly in the paprika xanthophyll group, but not in the placebo group. No adverse effects were caused by intake of paprika xanthophyll capsules. CONCLUSIONS: Intake of paprika xanthophylls for 12 weeks significantly reduced the abdominal fat area and BMI in healthy overweight volunteers without causing any adverse effects. These findings suggest that paprika xanthophyll is a safe food ingredient that improves lipid metabolism and reduces abdominal fat. TRIAL REGISTRATION: UMIN-CTR UMIN000021529.

CT-based attenuation correction and resolution compensation for I-123 IMP brain SPECT normal database: a multicenter phantom study.

OBJECTIVE: Statistical image analysis of brain SPECT images has improved diagnostic accuracy for brain disorders. However, the results of statistical analysis vary depending on the institution even when they use a common normal database (NDB), due to different intrinsic spatial resolutions or correction methods. The present study aimed to evaluate the correction of spatial resolution differences between equipment and examine the differences in skull bone attenuation to construct a common NDB for use in multicenter settings. METHODS: The proposed acquisition and processing protocols were those routinely used at each participating center with additional triple energy window (TEW) scatter correction (SC) and computed tomography (CT) based attenuation correction (CTAC). A multicenter phantom study was conducted on six imaging systems in five centers, with either single photon emission computed tomography (SPECT) or SPECT/CT, and two brain phantoms. The gray/white matter I-123 activity ratio in the brain phantoms was 4, and they were enclosed in either an artificial adult male skull, 1300 Hounsfield units (HU), a female skull, 850 HU, or an acrylic cover. The cut-off frequency of the Butterworth filters was adjusted so that the spatial resolution was unified to a 17.9 mm full width at half maximum (FWHM), that of the lowest resolution system. The gray-to-white matter count ratios were measured from SPECT images and compared with the actual activity ratio. In addition, mean, standard deviation and coefficient of variation images were calculated after normalization and anatomical standardization to evaluate the variability of the NDB. RESULTS: The gray-to-white matter count ratio error without SC and attenuation correction (AC) was significantly larger for higher bone densities (p < 0.05). The count ratio error with TEW and CTAC was approximately 5% regardless of bone density. After adjustment of the spatial resolution in the SPECT images, the variability of the NDB decreased and was comparable to that of the NDB without correction. CONCLUSION: The proposed protocol showed potential for constructing an appropriate common NDB from SPECT images with SC, AC and spatial resolution compensation.

Underestimation of myocardial blood flow by dynamic perfusion CT: Explanations by two-compartment model analysis and limited temporal sampling of dynamic CT.

PURPOSE: Previous studies using dynamic perfusion CT and volume perfusion CT (VPCT) software consistently underestimated the stress myocardial blood flow (MBF) in normal myocardium to be 1.1-1.4 ml/min/g, whilst the O 15-water PET studies demonstrated the normal stress MBF of 3-5 ml/min/g. We hypothesized that the MBF determined by VPCT (MBF-VPCT) is actually presenting the blood-to-myocardium transfer constant, K1. In this study, we determined K1 using Patlak plot (K1-Patlak) and compared the results with MBF-VPCT. MATERIAL AND METHODS: 17 patients (66 ± 9 years, 7 males) with suspected coronary artery disease (CAD) underwent stress dynamic perfusion CT, followed by rest coronary CT angiography (CTA). Arterial input and myocardial output curves were analyzed with Patlak plot to quantify myocardial K1. Significant CAD was defined as >50% stenosis on CTA. A simulation study was also performed to investigate the influence of limited temporal sampling in dynamic CT acquisition on K1 using the undersampling data generated from MRI. RESULTS: There were 3 patients with normal CTA, 7 patients with non-significant CAD, and 7 patients with significant CAD. K1-patlak was 0.98 ± 0.35 (range 0.22-1.67) ml/min/g, whereas MBF-VPCT was 0.83 ± 0.23 (range 0.34-1.40) ml/min/g. There was a linear relationship between them: (MBF-VPCT) = 0.58 x (K1-patlak) + 0.27 (r(2) = 0.65, p < 0.001). The simulation study done on MRI data demonstrated that Patlak plot substantially underestimated true K1 by 41% when true K1 was 2.0 ml/min/g with the temporal sampling of 2RR for arterial input and 4RR for myocardial output functions. CONCLUSIONS: The results of our study are generating hypothesis that MBF-VPCT is likely to be calculating K1-patlak equivalent, not MBF. In addition, these values may be substantially underestimated because of limited temporal sampling rate.

Theoretical considerations in measurement of time discrepancies between input and myocardial time-signal intensity curves in estimates of regional myocardial perfusion with first-pass contrast-enhanced MRI.

The purpose of this study was to develop a method to determine time discrepancies between input and myocardial time-signal intensity (TSI) curves for accurate estimation of myocardial perfusion with first-pass contrast-enhanced MRI. Estimation of myocardial perfusion with contrast-enhanced MRI using kinetic models requires faithful recording of contrast content in the blood and myocardium. Typically, the arterial input function (AIF) is obtained by setting a region of interest in the left ventricular cavity. However, there is a small delay between the AIF and the myocardial curves, and such time discrepancies can lead to errors in flow estimation using Patlak plot analysis. In this study, the time discrepancies between the arterial TSI curve and the myocardial tissue TSI curve were estimated based on the compartment model. In the early phase after the arrival of the contrast agent in the myocardium, the relationship between rate constant K1 and the concentrations of Gd-DTPA contrast agent in the myocardium and arterial blood (LV blood) can be described by the equation K1={dCmyo(tpeak)/dt}/Ca(tpeak), where Cmyo(t) and Ca(t) are the relative concentrations of Gd-DTPA contrast agent in the myocardium and in the LV blood, respectively, and tpeak is the time corresponding to the peak of Ca(t). In the ideal case, the time corresponding to the maximum upslope of Cmyo(t), tmax, is equal to tpeak. In practice, however, there is a small difference in the arrival times of the contrast agent into the LV and into the myocardium. This difference was estimated to correspond to the difference between tpeak and tmax. The magnitudes of such time discrepancies and the effectiveness of the correction for these time discrepancies were measured in 18 subjects who underwent myocardial perfusion MRI under rest and stress conditions. The effects of the time discrepancies could be corrected effectively in the myocardial perfusion estimates.

Accumulation of Paprika Carotenoids in Human Plasma and Erythrocytes.

The accumulation (incorporation) of paprika carotenoid in human plasma and erythrocytes was investigated. A paprika carotenoid supplement (14 mg/day) was ingested for 4 weeks by 5 young healthy volunteers (3 men and 2 women). After 2 weeks of carotenoid ingestion, the carotenoid levels in plasma and erythrocytes increased by 1.2-fold and 2.2-fold, respectively. Characteristic carotenoids found in paprika (capsanthin, cucurbitaxanthin A, and cryptocapsin) were detected in both plasma and erythrocytes. An oxidative metabolite of capsanthin (capsanthone) was also found in both plasma and erythrocytes.

Development of a method for automated and stable myocardial perfusion measurement using coronary X-ray angiography images.

The purpose of this study was to develop a method for automatic and stable determination of the optimal time range for fitting with a Patlak plot model in order to measure myocardial perfusion using coronary X-ray angiography images. A conventional two-compartment model is used to measure perfusion, and the slope of the Patlak plot is calculated to obtain a perfusion image. The model holds for only a few seconds while the contrast agent flows from artery to myocardium. Therefore, a specific time range should be determined for fitting with the model. To determine this time range, automation is needed for routine examinations. The optimal time range was determined to minimize the standard error between data points and their least-squares regression straight line in the Patlak plot. A total of 28 datasets were tested in seven porcine models. The new method successfully detected the time range when contrast agent flowed from artery to myocardium. The mean cross correlation in the linear regression analysis (R(2)) was 0.996 ± 0.004. The mean length of the optimal time range was 3.61 ± 1.29 frames (2.18 ± 1.40 s). This newly developed method can automatically determine the optimal time range for fitting with the model.

Differences in fatty acid metabolic disorder between ischemic myocardium and doxorubicin-induced myocardial damage: assessment using BMIPP dynamic SPECT with analysis by the Rutland method.

UNLABELLED: Dynamic myocardial SPECT data acquired with 15-(123)I-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) were analyzed by the Rutland method. The relative time-activity curves generated from dynamic SPECT in normal control subjects were compared with similar curves from patients with established ischemic heart disease (IHD) and doxorubicin-induced myocardial damage (DxMD). Comparison of such time-activity curves may provide some indirect information concerning qualitative differences in BMIPP metabolism. METHODS: Thirteen patients with various malignancies who received doxorubicin, 16 patients with IHD, and 15 normal control subjects were examined. Immediately after the bolus injection of BMIPP, dynamic data acquisition with a 3-head SPECT system was started and continued for 15 min. Using the time-activity curves of the myocardium as the output function (Mo(t)) and the time-activity curves of the left ventricular cavity as the input function (B(t)), the Rutland equation was calculated: Mo(t)/B(t) = F + K integral B(t)dt/B(t), where F is the blood - background subtraction factor and K is the uptake constant. The duration of the linear portion in this equation and the K values were evaluated. RESULTS: Mo(t)/B(t) was plotted against integral B(t)dt/B(t). Mo(t)/B(t) showed a good linear correlation with integral B(t)dt/B(t) from 30 s to 230 +/- 57 s in normal control subjects. The duration of this linearity was prolonged to 317 +/- 79 s in DxMD (P = 0.0014) and shortened to 182 +/- 58 s in IHD (P = 0.039). The mean K value was 0.0740 +/- 0.0184 in normal control subjects, significantly higher than the K values of 0.0599 +/- 0.0148 in DxMD patients (P = 0.026) and 0.0497 +/- 0.0189 (P = 0.0020) in IHD patients. CONCLUSION: Analysis of BMIPP dynamic SPECT data by the Rutland method is useful for detecting qualitative differences in BMIPP metabolism in various types of myocardial damage. It is speculated that the fatty acid metabolic disorder is characterized by a delay in metabolism in DxMD and by increased backdiffusion in IHD.