Enhancement Curve Research Articles

Intravoxel Incoherent Motion Magnetic Resonance Imaging for Prediction of Induction Chemotherapy Response in Locally Advanced Hypopharyngeal Carcinoma: Comparison With Model-Free Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

Multiparametric intravoxel incoherent motion (IVIM) provides diffusion and perfusion information for the treatment prediction of cancer. However, the superiority of IVIM over dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in locally advanced hypopharyngeal carcinoma (LAHC) remains unclear. To compare the diagnostic performance of IVIM and model-free DCE in assessing induction chemotherapy (IC) response in patients with LAHC. Prospective. Forty-two patients with LAHC. 3.0 T MRI, including IVIM (12 b values, 0-800 seconds/mm2 ) with a single-shot echo planar imaging sequence and DCE-MRI with a volumetric interpolated breath-hold examination sequence. IVIM MRI is a commercially available sequence and software for calculation and analysis from vendor. The IVIM-derived parameters (diffusion coefficient [D], pseudodiffusion coefficient [D*], and perfusion fraction [f]) and DCE-derived model-free parameters (Wash-in, time to maximum enhancement [Tmax], maximum enhancement [Emax], area under enhancement curve [AUC] over 60 seconds [AUC60 ], and whole area under enhancement curve [AUCw ]) were measured. At the end of IC, patients with complete or partial response were classified as responders according to the Response Evaluation Criteria in Solid Tumors. The differences of parameters between responders and nonresponders were assessed using Mann-Whitney U tests. The performance of parameters for predicting IC response was evaluated by the receiver operating characteristic curves. Twenty-three (54.8%) patients were classified as responders. Compared with nonresponders, the perfusion parameters D*, f, f × D*, and AUCw were significantly higher whereas Wash-in was lower in responders (all P-values <0.05). The f × D* outperformed other parameters, with an AUC of 0.84 (95% confidence interval [CI]: 0.69-0.93), sensitivity of 79.0% (95% CI: 54.4-93.9), and specificity of 82.6% (95% CI: 61.2-95.0). The IVIM MRI technique may noninvasively help predict the IC response before treatment in patients with LAHC. 2 TECHNICAL EFFICACY: Stage 2.

Background Parenchymal Enhancement on Breast MRI as a Prognostic Surrogate: Correlation With Breast Cancer Oncotype Dx Score.

PurposeBreast MRI background parenchymal enhancement (BPE) can potentially serve as a prognostic marker, by possible correlation with molecular subtype. Oncotype Dx, a gene assay, is a prognostic and predictive surrogate for tumor aggressiveness and treatment response. The purpose of this study was to investigate the association between contralateral non-tumor breast magnetic resonance imaging (MRI) background parenchymal enhancement and tumor oncotype score.MethodsIn this retrospective study, patients with ER+ and HER2− early stage invasive ductal carcinoma who underwent preoperative breast MRI, oncotype risk scoring, and breast conservation surgery from 2008–2010 were identified. After registration, BPE from the pre and three post-contrast phases was automatically extracted using a k-means clustering algorithm. Four metrics were calculated: initial enhancement (IE) relative to the pre-contrast signal, late enhancement, overall enhancement (OE), and area under the enhancement curve (AUC). Histogram analysis was performed to determine first order metrics which were compared to oncotype risk score groups using Mann–Whitney tests and Spearman rank correlation analysis.ResultsThis study included 80 women (mean age = 51.1 ± 10.3 years); 46 women were categorized as low risk (≤17) and 34 women were categorized as intermediate/high risk (≥18) according to Oncotype Dx. For the mean of the top 10% pixels, significant differences were noted for IE (p = 0.032), OE (p = 0.049), and AUC (p = 0.044). Using the risk score as a continuous variable, correlation analysis revealed a weak but significant correlation with the mean of the top 10% pixels for IE (r = 0.26, p = 0.02), OE (r = 0.25, p = 0.02), and AUC (r = 0.27, p = 0.02).ConclusionBPE metrics of enhancement in the non-tumor breast are associated with tumor Oncotype Dx recurrence score, suggesting that the breast microenvironment may relate to likelihood of recurrence and magnitude of chemotherapy benefit.

Dynamic contrast-enhanced MRI for response evaluation of non-small cell lung cancer in therapy with epidermal growth factor receptor tyrosine kinase inhibitors: a pilot study.

It is important to identify candidates who would benefit from target agent chemotherapy in advanced NSCLC patients. The purpose of this study is to evaluate the feasibility of DCE-MRI for early response evaluation in epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) treatment in patients with NSCLC. Seven patients were prospectively enrolled who have pathologically-proven NSCLC with EGFR mutations or at least 2 of the following factors; adenocarcinoma, female, or never-smokers. Patients were treated with gefitinib or erlotinib and the start of chemotherapy was denoted day 0. DCE-MRI was performed at day-1, day+7, and day+28. Longitudinal changes of perfusion parameters were quantified and compared to Response Evaluation Criteria in Solid Tumors (RECIST) results. Quantitative perfusion parameters; Ktrans, ve and vp of the lung cancer showed a significant decrease at day+7 (P=0.016), but no further significant decrease between day+7 and day+28 (P>0.05). Semiquantitative markers for tumor enhancement curve pattern; EA (enhancement amplitude), MS (maximum slope), and AUC (area under the curve) also showed a significant decrease at day+7 (P=0.016, 0.031, and 0.016, respectively), but no further significant decrease between day+7 and day+28 (P>0.05). When RECIST applied, all patient was in the stable disease at day+7 and three patients showed partial response (PR) at day+28. All seven patients showed PR by the 3-month follow-up. Perfusion parameters may be used as an early non-invasive imaging biomarker for the response evaluation of target agent treatment in NSCLC.

Exploring Optimization Merit Function-Based Plasmonic Resonance at NIR Using ITO

In this paper, indium tin oxide (ITO) is considered as an alternative plasmonic material beyond conventional plasmon generating metal. A total of 150-nm-thick ITO film-based Kretschmann configuration is demonstrated in NIR region. Minimum possible reflectance with optimum FWHM of resonance plot is the essential criteria for the incident angle selection of the said structure to increase the sensitivity and improve the performance of SPR biosensors in wavelength interrogation mode. Reflectance, phase, and field enhancement curves have been studied for different gaseous samples, and corresponding wavelength sensitivity has been calculated for the change of refractive index of the sample in the order of two. Differential resonance parameters have also been studied which are found to provide increased sensitivity. Theoretical simulation-based results validate that the proposed sensor can provide higher sensitivity by measuring the differential phase.

Feasibility of a multiparametric MRI protocol for imaging biomarkers associated with neoadjuvant radiotherapy for soft tissue sarcoma.

Objective:Soft tissue sarcoma (STS) is a rare malignancy with a 5 year overall survival rate of 55%. Neoadjuvant radiotherapy is commonly used in preparation for surgery, but methods to assess early response are lacking despite pathological response at surgery being predictive of overall survival, local recurrence and distant metastasis. Multiparametric MR imaging (mpMRI) is used to assess response in a variety of tumours but lacks a robust, standardised method. The overall aim of this study was to develop a feasible imaging protocol to identify imaging biomarkers for further investigation.Methods:15 patients with biopsy-confirmed STS suitable for pre-operative radiotherapy and radical surgery were imaged throughout treatment. The mpMRI protocol included anatomical, diffusion-weighted and dynamic contrast-enhanced imaging, giving estimates of apparent diffusion coefficient (ADC) and the area under the enhancement curve at 60 s (iAUC60). Histological analysis of resected tumours included detection of CD31, Ki67, hypoxia inducible factor and calculation of a hypoxia score.Results:There was a significant reduction in T1 at visit 2 and in ADC at visit 3. Significant associations were found between hypoxia and pre-treatment iAUC60, pre-treatment ADC and mid-treatment iAUC60. There was also statistically significant association between mid-treatment ADC and Ki67.Conclusion:This work showed that mpMRI throughout treatment is feasible in patients with STS having neoadjuvant radiotherapy. The relationships between imaging parameters, tissue biomarkers and clinical outcomes warrant further investigation.Advances in knowledge:mpMRI-based biomarkers have good correlation with STS tumour biology and are potentially of use for evaluation of radiotherapy response.

Comparison of clinical and magnetic resonance imaging findings of triple-negative breast cancer with non-triple-negative tumours.

PurposeTriple-negative breast cancer (TNBC) has some distinctive features. The aim of the study was to compare clinical and breast magnetic resonance imaging (MRI) findings of TNBC with non-triple-negative breast cancer (nTNBC) in molecular subtypes such as ADC (apparent diffusion coefficient) values, T2-weighted (T2W) image intensity, shape, margin, lymph node involvement, grade, multifocality, multicentricity, bilaterality, and enhancement pattern differences between tumour subtypes.Material and methodsA total of 141 patients who underwent breast biopsy at our institution between January 2010 and June 2018 were included in this study. Patients were divided into molecular subtypes according to hormone receptor status, and Ki-67 index. Tumour grade, enhancement patterns, age, lymph node involvement, ADC values, breast imaging reporting and data system (BI-RADS) category, bilaterality, multifocality, multicentricity, margin, shape, and T2W image intensity were evaluated for these subtypes.ResultsADC values were higher in triple-negative tumours than in luminal A and luminal B tumours (p = 0.010 and p = 0.002, respectively). Circumscribed margin, type 2 enhancement curve, and rim enhancement were significantly higher in triple-negative tumours (p < 0.001). No significant difference was found between the groups in terms of other MRI findings including bilaterality, multifocality, multicentricity, shape, and T2W image intensity (p > 0.05).ConclusionsADC values, circumscribed margin, and rim enhancement can provide important information about the tumour’s biological behaviour and the course of the disease.

Invasive breast carcinoma with MRI kinetic curve type 1

Breast cancer is the most common cancer in women and is the most significant cause of morbidity and mortality in women cancer patients. Increased awareness of people followed by periodic screening, appropriate supporting examinations, and imaging modalities according to the patient's condition could improve prognosis.&#x0D; We report a case report of a 55-year-old woman with a complaint of a lump in the right breast. Ultrasound examination and mammography showed a single solid lesion in the superior quadrant of the right breast corresponding to Breast Imaging-Reporting and Data System (BI-RADS) 4c. Magnetic Resonance Imaging (MRI) examination revealed a single lesion with enhancement curve type 1 according to bi-rads 4b. Results of the biopsy were grade 2 breast carcinoma without any lymph node metastases.&#x0D; The use of a single modality cannot be used as a benchmark in determining the best diagnosis and therapy. The kinetic feature/enhancement curve of Dynamic Contrast-Enhanced MRI (DCE-MRI) cannot be used as the main guide for determining the diagnosis. The morphology of the lesion either from ultrasound, mammography, or MRI should also be considered in determining the diagnosis and treatment plan

Cardiac magnetic resonance imaging myocardial perfusion reserve index in heart transplant patients

ObjectiveTo compare the myocardial perfusion reserve index (MPRI) measured during stress cardiac magnetic resonance imaging (MRI) with regadenoson in patients with heart transplants versus in patients without heart transplants. Material and methodsWe retrospectively compared 20 consecutive asymptomatic heart transplant patients without suspicion of microvascular disease who underwent stress cardiac MRI with regadenoson and coronary computed tomography angiography (CTA) to rule out cardiac allograft vasculopathy versus 16 patients without transplants who underwent clinically indicated stress cardiac MRI who were negative for ischemia and had no signs of structural heart disease. We estimated MPRI semiquantitatively after calculating the up-slope of the first-pass enhancement curve and dividing the value obtained during stress by the value obtained at rest. We compared MPRI in the two groups. Patients with positive findings for ischemia on stress cardiac MRI or significant coronary stenosis on coronary CTA were referred for conventional coronary angiography. ResultsMore than half the patients remained asymptomatic during the stress test. Stress cardiac MRI was positive for ischemia in two heart transplant patients; these findings were confirmed at coronary CTA and at conventional coronary angiography. Patients with transplants had lower end-diastolic volume index (59.3 ± 15.2 ml/m2 vs. 71.4 ± 15.9 ml/m2 in those without transplants, p = 0.03), lower MPRI (1.35 ± 0.19 vs. 1.6 ± 0.28 in those without transplants, p = 0.003), and a less pronounced hemodynamic response to regadenoson (mean increase in heart rate 13.1 ± 5.4 bpm vs. 28.5 ± 8.9 bpm in those without transplants, p < 0.001). ConclusionStress cardiac MRI with regadenoson is safe. In the absence of epicardial coronary artery disease, patients with heart transplants have lower MPRI than patients without transplants, suggesting microvascular disease. The hemodynamic response to regadenoson is less pronounced in patients with heart transplants than in patients without heart transplants.

Bionic optimization of MFCC features based on speaker fast recognition

Surrounded by low SNR, how to make the voice faster and better recognize the owner has become a heated research topic. The human auditory system can accurately acquire the characteristics of acoustic events in complex systems or low SNR noise environment, which is of significance in the research of bionic hearing of human ear. The response curve of human ear output is obtained by bionic technology, which is the best response curve for sound enhancement to modify Mel filter. The method of adaptive threshold selection is used to integrate Mel features to realize the reduction and dynamic extraction of low SNR speech features. This method not only can resist the disadvantages of poor robustness and complexity of parameter model, but also obtain dynamic and comprehensive speech information of different speakers in different scenes. Finally, the improved CNN and I-vector system are contributed to reduce the dimension of the data and to verify the recognition, so as to achieve the optimal frequency selective amplification and simplification of the acoustic signal. In the case of SNR-5db, the model is reduced by 15% and the recognition accuracy is improved by 3%.

Application of Contrast-Enhanced Ultrasound in the Differential Diagnosis of Different Molecular Subtypes of Breast Cancer

To explore the value of contrast-enhanced ultrasound (CEUS) in the differential diagnosis of molecular subtypes of breast cancer. Sixty-two cases of breast cancer were divided into luminal epithelium A or B subtype (luminal A/B), Her-2 over-expression subtype and triple negative subtype (TN). CEUS and routine ultrasonography were performed for all patients before surgery. (1) The luminal epithelium subtype contrast enhancement pattern was more likely to present with radial edge (76.92%, p < 0.05) and low perfusion (69.23%, p < 0.05). The maximum intensity (IMAX) was lower in the luminal epithelium subtype (p < 0.05). (2) The Her-2 over-expression subtype contrast enhancement pattern was more likely to present with centripetal enhancement (93.75%, p < 0.05) and perfusion defect (75.0%, p < 0.05), and the time to peak (TTP) was shorter (80.0%, p < 0.05). (3) The contrast enhancement pattern of the triple negative subtype was shown to have a clear boundary. Compared to the other two subtypes, the triple negative subtype did not have significantly different perfusion parameters (p > 0.05). (4) Our study showed that the areas under the ROC curve for radial edge, low perfusion and IMAX for the luminal epithelium subtype breast lesions were 76.5%, 75.6%, and 82.1%, respectively. Additionally, the areas under the ROC curve for centripetal enhancement, perfusion defect and TTP for the Her-2 over-expression subtype breast lesions were 68.6%, 92.4%, and 97.8%, respectively. The sensitivity, specificity, and diagnostic accuracy of clear boundaries in detecting triple negative subtype breast lesions were 90.5%, 80.0%, and 91.9%, respectively.

Prostatitis, the Great Mimicker of Prostate Cancer: Can We Differentiate Them Quantitatively With Multiparametric MRI?

OBJECTIVE. The purpose of this study was to investigate the diagnostic performance of semiquantitative and quantitative pharmacokinetic parameters and quantitative apparent diffusion coefficient (ADC) values obtained from prostate multiparametric MRI (mpMRI) to differentiate prostate cancer (PCa) and prostatitis objectively. MATERIALS AND METHODS. We conducted a retrospective review of patients with biopsy-proven PCa or prostatitis who underwent mpMRI study between January 2015 and February 2018. Mean ADC, forward volume transfer constant (Ktrans), reverse volume transfer constant (kep), plasma volume fraction (Vp), extravascular extracellular space volume fraction (Ve), and time to peak (TTP) values were calculated for both lesions and contralateral normal prostate tissue. Signal intensity-time curves were analyzed. Lesion-to-normal prostate tissue ratios of pharmacokinetic parameters were also calculated. The diagnostic accuracy and cutoff points of all parameters were analyzed to differentiate PCa from prostatitis. RESULTS. A total of 138 patients (94 with PCa and 44 with prostatitis) were included in the study. Statistically, ADC, quantitative pharmacokinetic parameters (Ktrans, kep, Ve, and Vp), their lesion-to-normal prostate tissue ratios, and TTP values successfully differentiated PCa and prostatitis. Surprisingly, we found that Ve values were significantly higher in prostatitis lesions. The combination of these parameters had 92.7% overall diagnostic accuracy. ADC, kep, and TTP made up the most successful combination for differential diagnosis. Analysis of the signal intensity-time curves showed mostly type 2 and type 3 enhancement curve patterns for patients with PCa. Type 3 curves were not seen in any prostatitis cases. CONCLUSION. Quantitative analysis of mpMRI differentiates PCa from prostatitis with high sensitivity and specificity, appears to have significant potential, and may improve diagnostic accuracy. In addition, evaluating these parameters does not cause any extra burden to the patients.

Leptomeningeal Enhancement on 3D-FLAIR MRI in Multiple Sclerosis: Systematic Observations in Clinical Practice.

Meningeal inflammation is implicated in cortical demyelination and disability progression in multiple sclerosis (MS). Gadolinium (Gd)-enhanced 3-dimensional (3D) FLAIR (fluid-attenuated inversion recovery) magnetic resonance imaging (MRI) can identify leptomeningeal enhancement (LME) in MS. Further characterization is needed to determine if LME is an imaging biomarker for meningeal inflammation. We sought to characterize the natural history of LME in the community setting, including persistence/resolution, effect of disease-modifying therapy, scanner variability, timing of acquisition, and imaging pitfalls that may lead to misinterpretation. A total of 341 MRI exams with Gd-enhanced 3D-FLAIR were reviewed in MS and non-MS patients to determine frequency of enhancement by MS subtype and association with therapy. A phantom was used to assess scanner variability. Two MS patients with seven LME were imaged at four postinjection time points to generate time-intensity curves. Imaging pitfalls were compiled. A total of 16.6% (40/241) of MS patients revealed LME compared to 8% (8/100) in non-MS patients (P = .04). There was no association with MS subtype, therapy, or disease activity. Detection using General Electric's version of 3D-FLAIR (29%) was greater than with Siemen's 3D-FLAIR (12%) at 1.5T (Tesla) (P<.001). Lesions were generally stable but resolved in 2 patients following high-dose steroids. LME kinetics were heterogeneous, even within patients, without uniform optimal time for acquisition. Enhancement curves exhibited three different variations, similar to the two-compartment model. Imaging pitfalls included enhancements of uncertain biologic significance, cortical veins and anatomic structures, and imaging artifacts. Awareness of LME characteristics, variability with imaging parameters, and imaging pitfalls will facilitate determining the potential role as an imaging biomarker for meningeal inflammation.

The Effect of Registration on Voxel-Wise Tofts Model Parameters and Uncertainties from DCE-MRI of Early-Stage Breast Cancer Patients Using 3DSlicer.

We quantitatively investigate the influence of image registration, using open-source software (3DSlicer), on kinetic analysis (Tofts model) of dynamic contrast enhanced MRI of early-stage breast cancer patients. We also show that registration computation time can be reduced by reducing the percent sampling (PS) of voxels used for estimation of the cost function. DCE-MRI breast images were acquired on a 3T-PET/MRI system in 13 patients with early-stage breast cancer who were scanned in a prone radiotherapy position. Images were registered using a BSpline transformation with a 2cm isotropic grid at 100, 20, 5, 1, and 0.5PS (BRAINSFit in 3DSlicer). Signal enhancement curves were analyzed voxel-by-voxel using the Tofts kinetic model. Comparing unregistered with registered groups, we found a significant change in the 90th percentile of the voxel-wise distribution of Ktrans. We also found a significant reduction in the following: (1) in the standard error (uncertainty) of the parameter value estimation, (2) the number of voxel fits providing unphysical values for the extracellular-extravascular volume fraction (ve > 1), and (3) goodness of fit. We found no significant differences in the median of parameter value distributions (Ktrans, ve) between unregistered and registered images. Differences between parameters and uncertainties obtained using 100PS versus 20PS were small and statistically insignificant. As such, computation time can be reduced by a factor of 2, on average, by using 20PS while not affecting the kinetic fit. The methods outlined here are important for studies including a large number of post-contrast images or number of patient images.

Manganese–Fluorouracil Metallodrug Nanotheranostic for MRI-Correlated Drug Release and Enhanced Chemoradiotherapy

For cancer therapy, drug delivery systems are often limited by insufficient drug loading capacity, which usually results in systemic toxicity and heavy metabolic burden to excrete the carriers. Her...

Utilidad de la resonancia magnética dinámica con contraste para caracterizar tumores ováricos ecográficamente indeterminados

ObjectivesTo determine whether there is a significant relationship between the shape of the time-intensity curve on dynamic gadolinium-enhanced magnetic resonance imaging (MRI) of ovarian tumors classified as indeterminate at ultrasonography and the type of lesion (benign, borderline, or malignant) to enable an accurate presurgical diagnosis. Material and methodsWe used dynamic contrast-enhanced MRI to study 68 ovarian tumors that were classified as indeterminate at ultrasonography. We included only cases for which a definitive diagnosis (histologic diagnosis or ≥1 year stability on imaging tests) was available. Each case was classified as benign, borderline, or malignant.To analyze the MRI studies, we marked regions of interest in the lesion and in the myometrium (as a reference). We obtained a curve defined by the relation between the intensity of enhancement and time and classified each tumor according to four predefined curve types. We also analyzed semiquantitative parameters. Finally, we compared the results for each of the three groups of tumors. ResultsWe found significant associations (p <0.001) between the curves without early enhancement and benign and borderline lesions as well as between the curves with early enhancement and malignant lesions. Malignant lesions were significantly associated with the semiquantitative enhancement parameters: maximum (p=0.002), maximum relative (p=0.006), and relative (p=0.018). ConclusionsIn ovarian tumors classified as indeterminate at ultrasonography, dynamic contrast-enhanced MRI can be useful for classification as benign, borderline, or malignant because the malignant lesions are significantly associated with early enhancement curves.

An optimized test bolus for computed tomography pulmonary angiography and its application at 80\u2009kV with 10\u2009ml contrast agent

Computed tomography pulmonary angiography (CTPA) is usually used for pulmonary embolism (PE) detection. However, the determination of scan timing remains a challenge due to the short scan duration of CTPA. We aimed to develop an optimized test bolus to determine scan delay in CTPA. The time-enhancement curves were obtained by measuring the enhancement within a region of interest in the main pulmonary artery and vein. A total of 70 patients were randomly divided into two groups (n = 35 each): the control group underwent CTPA using the test bolus approach and the test group underwent CTPA using the biphasic time-enhancement curves approach. Tube voltages of 100 kVp and 80 kVp and 20 ml and 10 ml contrast agent were adopted in the control and test groups, respectively. The CT numbers, image quality, PE detection was evaluated. There was a point of intersection between the pulmonary artery and vein test bolus enhancement curves. The scan delay time (TDELAY) was obtained based on the time at intersection (TCROSS) and the scan duration (TSD): TDELAY = TCROSS − TSD. The mean CT numbers for pulmonary vein in the control were higher than those in the test group (all p < 0.001). The image quality for the pulmonary arteries in the test group was better than that in the control group (p < 0.01), with artifact reduction in the superior vena cava. Segmental PE could be detected using the optimized protocol. The radiation dose and iodine load in the test group were all lower than those in the control (p < 0.01). We established an approach to calculate the scan delay of CTPA, and this approach could be used for CTPA at 80 kVp with 10 ml contrast agent.

Simultaneous Dual-Contrast Imaging of Small Bowel With Iodine and Bismuth Using Photon-Counting-Detector Computed Tomography: A Feasibility Animal Study.

Dual-energy and multienergy computed tomography (DECT/MECT) has the potential to simultaneously visualize two contrast agents in the small bowel: arterial enhancement of iodine in the bowel wall and enteric enhancement of bismuth in the bowel lumen. The purpose of this study was to explore its feasibility in a swine study using a research whole-body photon-counting-detector (PCD) computed tomography (CT) system. A phantom study was initially performed to evaluate the quantification accuracy of iodine and bismuth separation from a single PCD-CT scan, which also served as the calibration reference for material decomposition of in vivo swine PCD-CT data. In the animal study, a test bolus scan was first performed to determine the time-attenuation curve for the arterial enhancement, based on which the timing of the PCD-CT dual-contrast scan was determined. A 600 mL homogeneous bismuth-saline solution (180 mL Pepto-Bismol + 420 mL normal saline) was orally administered to the pig using esophageal intubation. Approximately 1 hour after bismuth administration, 40 mL iodine contrast (Omnipaque 350, 5 mL/s) was injected intravenously. A PCD-CT scan was performed 13 seconds after the initiation of the contrast injection to simultaneously capture the arterial enhancement of iodine and the enteric enhancement of bismuth. To provide optimal material separation and quantification, all PCD-CT scans in both phantom and animal studies were operated at 140 kV with 4 energy thresholds of 25, 50, 75, and 90 keV. Using a generic image-based material decomposition method, the iodine and bismuth samples were successfully delineated and quantified in the phantom images with a root-mean-square-error of 1.32 mg/mL in iodine measurement and 0.64 mg/mL in bismuth measurement. In the pig study, the enhancing bowel wall containing iodine and the small bowel loop containing bismuth were not differentiable in the original PCD-CT images. However, they were clearly distinctive from each other in the iodine- and bismuth-specific images after material decomposition, as reviewed by an abdominal radiologist. In addition, quantitative analysis showed that the misclassification between the two contrast materials was less than 1.0 mg/mL. Our study demonstrated the feasibility of simultaneous imaging of iodine and bismuth in small bowel of swine using PCD-CT.

Dynamic Contrast - Enhanced Magnetic Resonance Imaging (DCE-MRI) in Diagnosis of Pulmonary Nodules

Abstract Background: The differentiation between the benign and malignant pulmonary nodules has been considered as a major challenge for many years. Despite the fact that biopsy and histopathological evaluation are crucial for the definitive diagnosis, recent non-invasive imaging modalities are prom-ising in their results. Aim of Study: The aim of this study is to evaluate the role of Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) in diagnosis of pulmonary nodules. Patients and Methods: This study is a cross-sectional study that has been conducted on 60 patients with lung nodules referred to Radio Diagnosis and Imaging Department from Chest and Oncology Departments through the period from September 2018 to September 2019. Results: There were statistically significant differences between malignant and benign cases in terms of maximum net enhancement (p=0.003) and ADC value (p < 0.001). The mean maximum net enhancement was 474±94.417, the mean washout ratio was 5.45±2.17%, and the mean ADC value was 1.2±0.34 X 10–3mm2/sec. Malignant cases had significantly higher maximum net enhancement, washout ratio, and lower ADC values. The maximum enhancement curve was a signif-icant discriminator, which yielded a sensitivity of 92.6% and specificity of 96% at a cut-off value of ³375. In contrary, the ADC value had poor diagnostic accuracy in differentiating between malignant and benign cases. Conclusion: Dynamic contrast-enhanced MRI is valuable for diagnosis of pulmonary nodules and discrimination of benign from malignant ones.

Valoración del índice de reserva de perfusión miocárdica por resonancia magnética en pacientes con trasplante cardíaco

ObjectiveTo compare the myocardial perfusion reserve index (MPRI) measured during stress cardiac magnetic resonance imaging (MRI) with regadenoson in patients with heart transplants versus in patients without heart transplants. Material and methodsWe retrospectively compared 20 consecutive asymptomatic heart transplant patients without suspicion of microvascular disease who underwent stress cardiac MRI with regadenoson and coronary computed tomography angiography (CTA) to rule out cardiac allograft vasculopathy versus 16 patients without transplants who underwent clinically indicated stress cardiac MRI who were negative for ischemia and had no signs of structural heart disease. We estimated MPRI semiquantitatively after calculating the up-slope of the first-pass enhancement curve and dividing the value obtained during stress by the value obtained at rest. We compared MPRI in the two groups. Patients with positive findings for ischemia on stress cardiac MRI or significant coronary stenosis on coronary CTA were referred for conventional coronary angiography. ResultsMore than half the patients remained asymptomatic during the stress test. Stress cardiac MRI was positive for ischemia in two heart transplant patients; these findings were confirmed at coronary CTA and at conventional coronary angiography. Patients with transplants had lower end-diastolic volume index (59.3±15.2 ml/m2 vs. 71.4±15.9 ml/m2 in those without transplants, p=0.03), lower MPRI (1.35±0.19 vs. 1.6±0.28 in those without transplants, p=0.003), and a less pronounced hemodynamic response to regadenoson (mean increase in heart rate 13.1±5.4 bpm vs. 28.5±8.9 bpm in those without transplants, p <0.001). ConclusionStress cardiac MRI with regadenoson is safe. In the absence of epicardial coronary artery disease, patients with heart transplants have lower MPRI than patients without transplants, suggesting microvascular disease. The hemodynamic response to regadenoson is less pronounced in patients with heart transplants than in patients without heart transplants.

MRI perfusion analysis using freeware, standard imaging software

BackgroundPerfusion-weighted imaging is only scarcely used in veterinary medicine. The exact reasons are unclear. One reason might be the typically high costs of the software packages for image analysis. In addition, a great variability concerning available programs makes it hard to compare results between different studies. Moreover, these algorithms are tuned for their usage in human medicine and often difficult to adapt to veterinary studies.In order to address these issues, our aim is to deliver a free open source package for calculating quantitative perfusion parameters. We develop an “R package” calculating mean transit time, cerebral blood flow and cerebral blood volume from data obtained with freely imaging software (OsiriX Light®). We hope that the free availability, in combination with the fact that the underlying algorithm is open and adaptable, makes it easier for scientists in veterinary medicine to use, compare and adapt perfusion-weighted imaging analysis.In order to demonstrate the usage of our software package, we reviewed previously acquired perfusion-weighted images from a group of eight purpose-breed healthy beagle dogs and twelve client-owned dogs with idiopathic epilepsy. In order to obtain the data needed for our algorithm, the following steps were performed: First, regions of interest (ROI) were drawn around different, previously reported, brain regions and the middle cerebral artery. Second, a ROI enhancement curve was generated for each ROI using a freely available PlugIn. Third, the signal intensity curves were exported as a comma-separated-value file. These files constitute the input to our software package, which then calculates the PWI parameters.ResultsWe used our software package to re-assess perfusion weighted images from two previous studies. The clinical results were similar, showing a significant increase in the mean transit time and a significant decrease in cerebral blood flow for diseased dogs.ConclusionWe provide an “R package” for computing the main perfusion parameters from measurements taken with standard imaging software and describe in detail how to obtain these measurements. We hope that our contribution enables users in veterinary medicine to easily obtain perfusion parameters using standard Open Source software in a standard, adaptable and comparable way.