Circular Region Of Interest Research Articles

A comparison of normal kidneys to those with chronic kidney disease using ultrasound shearwave elastography

Background Chronic kidney disease (CKD) is based on estimated glomerular filtration rate (eGFR) results in blood analysis. Patients also undergo diagnostic ultrasound to confirm and supplement the eGFR findings. Renal fibrosis is the end stage of CKD and has been subjectively evaluated with renal ultrasound. This study was designed to determine if patients with CKD will have a stiffer renal cortex compared to a normal control group using ultrasound shearwave elastography (SWE) in a quantifiable manner. Objectives The aim of this study is to measure and compare the renal cortical stiffness Young Modulus values in kilopascals (kPa) using SWE for normal and CKD participants. Methods Outpatient volunteers were recruited for this study. All participants were greater than 18 years of age. The normal control group had an eGFR results of greater than 90, while the CKD group had an eGFR of less than 60, within three months of the SWE measurements. Both groups did not have any evidence of hydronephrosis, renal calculus or distinct renal malignancies. After gaining consent, both groups underwent SWE as an extension to their routine diagnostic ultrasound examination of the upper abdomen or renal system. A brief medical questionnaire was completed by each volunteer. The bipolar renal length was recorded. The renal cortex elasticity values were measured with circular regions of interest placed in the upper, mid and lower zones of both kidneys and their corresponding Young's modulus (YM) SWE values measured in kilopascals (kPa) were recorded. Two sample unpaired t-tests was used to compare the measured renal stiffness SWE values (in kPa) between the normal control and CKD group. Results 40 participants were recruited, of those 20 had CKD and 20 control. The bipolar renal length was significantly reduced in CKD participants to 104mm ( ± 21mm) from control group of 111mm ( ± 11mm) (p = 0.03). The SWE values (in kPa) measuring the renal stiffness was significantly higher in the CKD group than those of normal controls (p Conclusion Participants with CKD had significantly higher (p

Diffusion weighted MR imaging in the diagnosis of acute pyelonephritis and its complications: A prospective observational study

Introduction: In diagnosing complicated pyelonephritis, imaging is essential for which traditionally computed tomography (CT) has been in use but in renal failure patients contrast enhanced CT can't be performed due to elevated serum creatine levels. This can be overcome with the help of Diffusion weighted (DW) magnetic resonance imaging (MRI). Purpose: To assess the morphological changes and signal abnormalities, in kidneys in patients with acute pyelonephritis (APN) on conventional MRI and DWI and to measure the ADC values in areas of abnormal signal intensity in DWI so as to differentiate between abscess and nephritis. Materials and Methods: In our study, 32 patients with clinical and laboratory diagnosis of pyelonephritis underwent conventional and Diffusion weighted MRI. Diffusion images were obtained by using a non-breath-hold, single-shot echo-planar sequence with b values of 50/400/800 s/mm2. Circular regions of interest were drawn in the areas of normal renal parenchyma, nephritis and abscesses. The ADC values of three tissue types were compared by using the paired t-test and ANOVA.P value Results: In our study, areas of normal renal parenchyma showed ADC values of (1.83 ± 0.06) × 10-3 mm2/s while areas of nephritis had ADC values of (1.20 ± 0.08) × 10-3 mm2/s which was significantly lower (P Conclusion: Diffusion weighted MR imaging is useful to diagnose abscess formation in patients with pyelonephritis without using IV contrast medium.

Role of apparent diffusion coefficient as a biomarker in the evaluation of cervical cancer.

Background:Diffusion-weighted magnetic resonance imaging (DW-MRI) has evolved as a major diagnostic and prognostic tool in cervical cancer. The aim of our study was to compare the change in mean apparent diffusion coefficient (ADC) value before and after concurrent chemoradiation therapy (CCRT) in carcinoma cervix thereby establishing its role as a cancer biomarker.Materials and Methods:A hospital-based prospective study was conducted in 35 patients diagnosed with cervical cancer. All 35 patients underwent pelvic MRI before and after 6 months of CCRT. The study was done over a period of 12 months. Conventional axial and sagittal T2 imaging was followed by DW-MRI. In the axial DW/ADC images at “b-value” of 800 s/mm2, a circular region of interest was drawn covering more than 60% of the tumor volume to calculate the ADC values. Statistical Package for the Social Sciences (version 21.0) was used for statistical evaluation. Chi-square test, independent samples t-test, and analysis of variance were used to analyze the data. The results are depicted as frequencies (number), proportion (percentages), and mean ± standard deviation.Results:Pre-CCRT mean ADC value was 0.814 × 10−3 mm2/s. Post-CCRT mean ADC value was 1.294 × 10−3 mm2/s. Mean ADC value of patients having lymph node involvement and parametrial extension was significantly lower when compared with those without lymph node involvement and parametrial extension (P = 0.001). Nonresponders with residual lesion had lower ADC values than responders with no residual lesion. An interesting and unique observation was that pre-CCRT mean ADC value of responders was higher than nonresponders.Conclusion:An increase in mean ADC value of 0.480 × 10−3 mm2/s after CCRT was found to be statistically significant (P < 0.001) thereby proving its role as an imaging biomarker in cancer cervix.

62 Kinetic data extraction from [formula omitted]F-FDOPA PET brain acquisition

Introduction The indications of Positron Emission Tomography (PET) using radiolabeled amino acids in neurology are growing especially for the diagnosis of brain tumors. The last classification “WHO 2016” (World Health Organization) concerning the gliomas implemented molecular parameters such as the IDH mutation and the 1p/19q co-deletion correlated with clinical observed outcomes. The aim of this study was to assess the diagnostic performance of the 18 F-FDOPA (L-3, 4-Dihydroxy-6- 18 F-fluoro-phenyl-alanine) from dynamic PET recordings. Methods Patients initially referred for newly diagnosed gliomas had been sorted according to the WHO classification into 3 distinct groups: oligodendrogliomas, astrocytomas IDH + and glioblastomas according to the anatomico-pathological results. Dynamic recordings were performed on a Biograph6 True Point (Siemens Healthcare) PET scanner after the injection of 3 MBq of 18F-FDOPA/kg. For each patient, a scan of 30 min was performed immediately after the intravenous injection. The data had been reconstructed in dynamic method with a 2D OSEM iterative algorithm (2 iterations, 21 subsets, Gaussian filtering with a FWMH of 4 mm) and an adapted temporal sampling, allowing a compromise between kinetic information and noise. A circular region of interest (ROI) with a diameter of 2 cm was centered on the pixel of the maximum tumor uptake on the static images (summed of the dynamic images). Then, this ROI was applied to the entire dynamic dataset in order to obtain the time-activity curve (TAC) of the 18 F-FDOPA uptake in the tumor. The slope of the curve was obtained by fitting with a linear regression function the data recorded between 10 and 30 min post-injection. Results Dynamic PET images were reconstructed into 30 time-frames of 1 min each. The TAC obtained with raw data were fitted with the following Eq. (1) SUV ( t ) = a 0 + ( a 1 - a 0 ) × A + ( t a 2 ) p B + ( t a 2 ) q and the mean correlation coefficient R2 was equal to 0,958. The time corresponding to the maximum of the tumor fixation was superior to 20 min after the injection for the oligodendrogliomas and astrocytomas IDH + whereas it was about 6 min for the glioblastomas. The slopes of the TAC were positive for the oligodendrogliomas (+0,3 SUV/h), negative for the astrocytomas IDH+ (-0,8 SUV/h) and more negative for the glioblastomas (-6 SUV/h). Conclusions Dynamic 18 F-FDOPA PET recordings could be used to extract quantitative parameters allowing non-invasive staging of gliomas in patients referred for initial diagnosis.

OA082] Towards normalization of contrast enhancement of pulmonary parenchyma on subtraction CT imaging

Purpose To determine the impact of patient and acquisition parameters on the quantification of the enhancement of pulmonary parenchyma in subtraction computed tomography pulmonary angiography (CTPA) imaging in patients without pulmonary pathology. Methods 2515 patients underwent clinical CTPA with subtraction imaging on a 320-multidetector row CT scanner (Aquilion ONE VISION or GENESIS, Canon Medical Systems Corporation, Japan) between January 2013 and August 2017 for suspicion of pulmonary embolism. In subtraction CT, an unenhanced chest CT is subtracted from an enhanced CT after motion correction, resulting in an iodine map representing pulmonary perfusion. After examination of patient records and images, 74 patients (2.9 %) without any apparent pulmonary or systemic pathology were selected. The mean enhancement in circular regions of interest (ROI) in all lung lobes of the iodine maps, placed to avoid vessels depicted in the CTPA images, were calculated. Patient age, sex, BMI, and smoking habits, as well as CT scan time, diaphragm position and lung volume changes between the unenhanced and enhanced CT, type and volume of contrast, and enhancement in the aortic arch, pulmonary trunk and left atrium were collected. Linear regression analysis was used to evaluate the correlation between the parameters and the measured enhancement. Results The mean enhancement of the ROIs throughout the whole lung was 32.2 ± 21.6 HU. The enhancement in the lower lobes (39.4 ± 24.3 HU) was significantly higher than in the upper lobes (31.7 ± 22.3 HU, p r 2 = 0.54 p 0.001 ) , and with lung volume changes ( r 2 = 0.73 p 0.001 ) between the scans. No correlation was found between the mean enhancement and all other variables studied. Conclusions The enhancement of the pulmonary parenchyma on subtraction CT imaging in patients without pulmonary pathology varies widely. However, normal enhancement values correlate strongly with changes in diaphragm position and in pulmonary volume between scans. This implies that normalization of lung enhancement based on lung volume changes could improve clinical interpretation and would be the first step towards quantification of enhancement in subtraction CT imaging.

P026] Dose and image quality evaluation in computed tomography with an anthropomorphic phantom

Purpose Clinical PET/CT exams include a CT for attenuation correction and anatomical localization. The purpose of this study is to: • Evaluate if an anthropomorphic phantom is suitable to mimic clinical conditions regarding CT automated current modulation behaviour. • Describe the variation of the image noise as a function of reference mAs in the phantom, in order to predict noise level in clinical patients. Methods CT scans were performed with a 64-slice Somatom Definition AS CT mounted in a Biograph mCT TrueV PET/CT system, with 120 kV, 0.5 s rotation time, pitch 1 and automated current modulation. A sample of 94 patients scanned with our PET/CT clinical protocol (80 reference mAs) was reviewed. Patients similar to the “standard-man” were selected (N = 18, men with weigh 65–75 kg). The parameters of the CT exploration (effective mAs and CTDIvol) were registered. An anthropomorphic phantom (3D Torso Phantom, CIRS) was scanned with different reference mAs. Effective mAs and CTDIVol were recorded. Several circular regions of interest were drawn in lung, bone and soft tissue. Noise was quantified as the mean of standard deviation in Hounsfield Units (HU). Results Clinical CT for the “standard-man” was acquired with 49.5 ± 5.7 effective mAs and CTDIvol of 3.62 ± 0.4 mGy. When the CIRS phantom was scanned with 80 reference mAs, 45 effective mAs and a CTDIvol of 3.28 mGy were produced. One-sample t-test showed statistically significant differences between the patients sample and the phantom (p Noise measured in the phantom with 80 reference mAs was 41.9 HU in bone, 15.2 HU in lung and 22.6 HU in soft tissue. When reference mAs varied from 10 to 120 mAs, noise in lung, bone and soft tissue varied as a potential function of effective mAs with R2 greater than 0.94. Conclusions There is no concordance between the anthropomorphic phantom and the clinical studies. A function to model the relation between effective mAs and noise has been determined with a good fit.

The role of FDG-PET in detecting rejection after liver transplantation

BackgroundThe activation and increased metabolic activity of T cells in acute cellular rejection could allow fluoro-2-deoxyglucose positron emission tomography to be utilized for detection of acute cellular rejection. The objective of this study was to evaluate the effectiveness of fluoro-2-deoxyglucose positron emission tomography in detecting acute cellular rejection in the clinical setting. MethodsFluoro-2-deoxyglucose positron emission tomography studies were performed on 88 orthotopic liver transplant patients at 7 and 17 days postoperatively (first positron emission tomography and second positron emission tomography, respectively). Additional studies were performed if patients had suspicion of rejection and at resolution of rejection (third positron emission tomography and fourth positron emission tomography, respectively). A circular region of interest was placed over the liver for semiquantitative evaluation of fluoro-2-deoxyglucose positron emission tomography images by means of standard uptake values. ResultsEighteen of 88 patients in our study (20.5%) had histologically proven acute cellular rejection during a 16 ± 11 day follow-up. There was no significant difference between the standard uptake values of first positron emission tomography among non-rejecters versus rejecters (2.05 ±0.46 non-rejecters versus 1.82 ± 0.40 rejecters, P = .127). Within the rejection cohort, the standard uptake values from the third positron emission tomography (rejection) were higher compared to the first positron emission tomography (baseline) (2.41 ± 0.48 third positron emission tomography versus 1.82 ± 0.41 first positron emission tomography, P < .001). ConclusionIncreased signal on fluoro-2-deoxyglucose positron emission tomography over baseline is associated with acute cellular rejection in liver transplant recipients. Additional prospective validation studies are essential to define the role of fluoro-2-deoxyglucose positron emission tomography scan as an early marker for acute cellular rejection.

Abstract 3858: Validation of digital spatial profiling of key immuno-oncology targets for mouse FFPE preclinical models

Abstract Mouse models of cancer are an invaluable biomedical research tool in which characterization of the abundance, distribution and co-localization of immuno-oncology targets is critical for the advancement of disease understanding. Nanostring Technologies' Digital Spatial Profiling (DSP) technology allows for the simultaneous analysis of 10s to 100s of proteins from discrete regions of interest (ROI), providing a spatial context to multiplexed data. The purpose of this study is to validate an antibody panel designed to characterize key tumor and immunology markers on the DSP platform. DSP technology utilizes barcoded oligo tags that are covalently linked to detection reagents, in this case, antibodies. The workflow for a typical DSP experiment consists of incubating a formalin-fixed, paraffin-embedded (FFPE) tissue with a cocktail of oligo-labeled primary antibodies and three fluorescently labeled visualization markers. The visualization markers and tissue morphology guide the selection of ROIs. UV light then illuminates each ROI, releasing the oligo tags through a UV photocleavable linker. Tags are collected through microcapillary aspiration and then deposited into a microtiter plate for further analysis on the standard nCounter® platform. In order to validate antibodies for this technology, the specificity and sensitivity of each antibody was evaluated for proper immunohistochemistry (IHC) staining pattern on appropriate tissues as well as signal-to-noise ratios of positive counts above background. Panels will also undergo an evaluation of single vs. multiplex interactions to ensure there are no deleterious effects of multiplexing antibodies. Immunohistochemical analysis of antibodies chosen for panel displays indistinguishable staining patterns on mouse control tissues for unconjugated primary antibodies and oligo-conjugated primary antibodies. Visualization markers allow for an ROI selection strategy that utilizes a range of circular ROIs (e.g., 50-650um) as well as custom masking of areas of interest. Key immuno-oncology targets including B7-H3, beta-catenin, CD19, CD25, CD3, CD4, histone H3, Ly-6G, pan-cytokeratin, PD-1, PD-L1, F4/80, Ki-67, STAT3, etc., have been validated thus far. Ongoing validation efforts will continue to expand this antibody panel. Nanostring Technologies' DSP platform is applicable not only to human tissue but also to mouse preclinical samples. Antibody specificity, sensitivity and interaction within a cocktail have been validated for this application. DSP technology allows for the multiplexing of important mouse immuno-oncology markers so that researchers can evaluate the abundance as well as the spatial distribution of these key targets simultaneously. Citation Format: Sarah Warren, Heather Metz, Kristi Barker, JingJing Gong, Alison VanSchoiack, Quoc Huynh, Chris Merritt, Lucas Dennis, Yan Liang, Joseph M. Beechem. Validation of digital spatial profiling of key immuno-oncology targets for mouse FFPE preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3858.

Dual-Energy CT-Derived Iodine Content and Spectral Attenuation Analysis of Metastatic Versus Nonmetastatic Lymph Nodes in Squamous Cell Carcinoma of the Oropharynx.

The presence of a single nodal metastasis has significant prognostic and treatment implications for patients with head and neck cancer. This study aims to investigate whether dual-energy computed tomography (DECT)-derived iodine content and spectral attenuation curve analysis can improve detection of nodal metastasis in oropharyngeal carcinoma. Eight patients with newly diagnosed oropharyngeal squamous cell carcinoma and pathologically proven nodal metastatic disease (n = 13 metastatic nodes; n = 16 nonmetastatic nodes) who underwent contrast-enhanced DECT of the neck were retrospectively evaluated. DECT-derived iodine content (mg/mL) and monoenergetic attenuation values at 40 keV and 100 keV were obtained via circular regions of interest within metastatic and nonmetastatic cervical lymph nodes. Iodine content was significantly lower in metastatic nodes (0.96 ± 0.28 mg/mL) than in nonmetastatic nodes (1.65 ± 0.38 mg/mL; P = .002). Iodine spectral attenuation slope was significantly lower in metastatic nodes (1.33 ± 0.49 mg/mL) than in nonmetastatic nodes (1.91 ± 0.64 mg/mL; P = .015). A nodal iodine threshold of ≤1.3 mg/mL showed a sensitivity of 84.6% and a specificity of 75.0%, with an area under the curve of 0.839, P < .0001. At a threshold value of ≤1.95 for nodal spectral attenuation slope, an optimized specificity of 92.3% and specificity of 50.0% was achieved, with an area under the curve of 0.68 (P = .049). DECT-derived quantitative iodine data and spectral attenuation curves may improve the diagnostic accuracy of computed tomography for nodal metastasis in patients with squamous cell carcinoma of the oropharynx.

Meningioma Consistency: Correlation Between Magnetic Resonance Imaging Characteristics, Operative Findings, and Histopathological Features.

Introduction:Intracranial meningiomas account for 30% of all primary intracranial tumors. Surgical resection remains the mainstay of the treatment for meningiomas. The magnetic resonance of intracranial meningiomas has been largely discussed in many reports of the radiological and neurosurgical literature. To date, a few studies have been attempted to differentiate the tumor characteristics of meningiomas based on magnetic resonance imaging (MRI) studies.Objective:The objective of the study is to evaluate the relationship between MRI signal characteristics of intracranial meningiomas and consistency of tumor using objective measures.Materials and Methods:A prospective study included all the patients who were admitted for surgery with an MRI finding suggestive of meningioma. All patients were subjected to routine radiological investigations. Surgical resection was performed for patients eligible for surgery using cavitron ultrasonic aspirator (CUSA). The relationship and correlation between the radiological, intraoperative measurements and the histopathological diagnosis were studied. The tumor consistency was measured using mean CUSA level. Intensity on T2, fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI) was measured using circular regions of interest (ROI) on the MRI. Multiple ROIs were placed initially on the lesions avoiding the obvious blood vessels, if any, then on the brain cortex to avoid the vasogenic edema. The mean ROI (mROI) results from the lesion were subtracted from the mean ROI from the brain cortex for each lesion to achieve normalized ratio. The results of lesion mROI-cortex mROI were compared to the operative and histopathology results using Pearson's correlation test and linear regression test.Results:The total number of patients was seventy. The mean age of the patients was 51 ± 14.8, with 72% of them being females and 28% males. There was a strong statistically significant (P = 0.046) and (P = 0.003) correlation between mean CUSA and FLAIR mROI difference or T2 mROI difference, respectively. On the other hand, there was an inversely proportional relationship between mean CUSA and FLAIR mROI difference and mean CUSA and T2 mROI difference. The value of the regression test (r) shows that there was a slight linear relationship between FLAIR mROI difference or T2 mROI difference and mean CUSA values, in which the mean CUSA value = 50.1 + (−0.088) × FLAIR mROI difference (r = −0.273, P = 0.046) or mean CUSA value = 50.8 + (−0.055) × T2 mROI difference (r = 0.4, P = 0.003). There was no statistical significance in the relation between CUSA values and tumor histological subtypes, DWI values, age, or gender.Conclusion:This study presents a new objective method to measure the consistency of intracranial meningiomas based on a simple algorithmic formula. Such information will aid in planning surgery and assessing the resectability of the tumor. To date, this is the first objective measurement of meningioma consistency based on MRI studies and objective intraoperative evaluation.

Changes in the ADC of diffusion-weighted MRI with the oscillating gradient spin-echo (OGSE) sequence due to differences in substrate viscosities.

Compared with the conventional pulsed gradient spin-echo (PGSE) sequence, diffusion-weighted imaging (DWI) with the oscillating gradient spin-echo (OGSE) sequence can shorten the diffusion time by changing the frequency. The purpose was to investigate whether n-alkanes are suitable as isotropic phantoms for estimating the diffusion coefficient with the OGSE sequence. We investigated changes in the apparent diffusion coefficient (ADC) due to differences in the viscosities of nine n-alkane phantoms with different numbers of carbon atoms from C8H18 to C16H34 using OGSE and PGSE sequences at 21°C. Effective diffusion times of 4.3, 5.1, 6.5, 9.3, 20, 40, and 60ms were used. The T2 relaxation times of each n-alkane phantom were measured using quantitative synthetic magnetic resonance imaging (MRI). Circular regions of interest were placed manually within the alkane phantoms on ADC and T2 maps. In each alkane phantom, changes in mean ADC values were almost constant with changes in diffusion times. Viscosities and ADC values showed inverse proportionality, as expected theoretically. The ADC values of alkanes do not depend on diffusion times. The n-alkanes can be useful phantoms for assessing the accuracy of clinical protocols of DWI with the OGSE sequence.

Application and advantages of monoenergetic reconstruction images for the reduction of metallic artifacts using dual-energy CT in knee and hip prostheses.

The study aimed to assess image quality when using dual-energy CT (DECT) to reduce metal artifacts in subjects with knee and hip prostheses. Twenty-two knee and 10 hip prostheses were examined in 31 patients using a DECT protocol (tube voltages 100 and 140 kVp). Monoenergetic reconstructions were extrapolated at 64, 69, 88, 105, 110, 120, 140, 170, and 190 kilo-electron volts (keV) and the optimal energy was manually selected. The B60-140 and Fast DE reconstructions were made by CT. The image quality and diagnostic value were subjectively and objectively determined. Double-blind qualitative assessment was performed by two radiologists using a Likert scale. For quantitative analysis, a circular region of interest (ROI) was placed by a third radiologist within the most evident streak artifacts on every image. Another ROI was placed in surrounding tissues without artifacts as a reference. The inter-reader agreement for the qualitative assessment was nearly 100%. The best overall image quality (37.8% rated "excellent") was the Fast DE Siemens reconstruction, followed by B60-140 and Opt KeV (20.5 and 10.2% rated excellent). On the other hand, DECT images at 64, 69 and 88keV had the worse scores. The number of artifacts was significantly different between monoenergetic images. Nevertheless, because of the high number of pairwise comparisons, no differences were found in the post hoc analysis except for a trend toward statistical significance when comparing the 170 and 64keV doses. DECT with specific post-processing may reduce metal artifacts and significantly enhance the image quality and diagnostic value when evaluating metallic implants.

Qualitative and quantitative ultrasound attributes of maternal-foetal structures in pregnant ewes.

The aim of this study was to examine foetal organs and placental tissue to establish a correlation between the changes in the composition of these structures associated with their maturation and the ultrasonographic characteristics of the images. Twenty-four pregnant ewes were included in the study. Ultrasonography assessments were performed in B-mode, from the ninth gestational week until parturition. The lungs, liver and kidneys of foetuses and placentomes were located in transverse and longitudinal sections to evaluate the echogenicity (hypoechoic, isoechoic, hyperechoic or mixed) and echotexture (homogeneous and heterogeneous) of the tissues of interest. For quantitative evaluation of the ultrasonographic characteristics, it was performed a computerized image analysis using a commercial software (Image ProPlus® ). Mean numerical pixel values (NPVs), pixel heterogeneity (standard deviation of NPVs) and minimum and maximum pixel values were measured by selecting five circular regions of interest in each assessed tissue. All evaluated tissues presented significant variations in the NPVs, except for the liver. Pulmonary NPVmean, NPVmin and NPVmax decreased gradually through gestational weeks. The renal parameters gradually decreased with the advancement of the gestational weeks until the 17th week and later stabilized. The placentome NPVmean, NPVmin and NPVmax decreased gradually over the course of weeks. The hepatic tissue did not show echogenicity and echotexture variations and presented medium echogenicity and homogeneous echotexture throughout the experimental period. It was concluded that pixels numerical evaluation of maternal-foetal tissues was applicable and allowed the identification of quantitative ultrasonographic characteristics showing changes in echogenicity related to gestational age.

18F-PSMA-1007 PET/CT at 60 and 120 minutes in patients with prostate cancer: biodistribution, tumour detection and activity kinetics.

PSMA-targeted PET in patients with prostate cancer (PCa) has a significant impact on treatment decisions. By far the most frequently used PSMA ligand is 68Ga-labelled PSMA-11. However, due to the availability of larger amounts of activity, 18F-labelled PSMA ligands are of major interest. The aim of the present study was to evaluate the biodistribution and performance of the novel 18F-labelled ligand PSMA-1007 at two different time points. This retrospective analysis included 40 consecutive patients (mean age 68.7 ± 8.1 years) referred for PSMA PET/CT. 18F-PSMA-1007 PET/CT was performed for localization of biochemical relapse, primary staging or therapy follow-up. Circular regions of interest were placed on representative slices of the liver, spleen, kidney, abdominal aortic blood pool, bone marrow (fourth lumbar vertebral body), urinary bladder and gluteus muscle at 60 and 120 min after injection. In malignant lesions the maximum standardized uptake (SUVmax) was measured within volumes of interest at both time points. All SUVs at 60 min were compared with those at 120 min after injection. The activity in the blood pool, urinary bladder and gluteus muscle was very low and decreased significantly over time (P < 0.001). Uptake in the liver, spleen and kidney showed a significant increase over time and uptake in the bone marrow remained stable. Overall, 135 PCa lesions were detected at 60 min and 136 lesions at 120 min after injection. The median SUVmax increased significantly (P < 0.001) from 10.98 to 15.51 between 60 and 120 min. PCa lesions show a significant increase in 18F-PSMA-1007 uptake at 120 min compared with 60 min after injection. In addition, accumulation of the tracer in the urinary bladder was very low leading to improved contrast of adjacent PCa lesions. Increasing accumulation in the liver may limit the sensitivity of the tracer in detecting liver metastases.

Influence of Different Contrast Agent Concentrations and Injection Protocols on Dynamic Contrast Enhanced MRI of Prostate: Equimolar Comparison of 1.0M Gadobutrol and 0.5M Gadolinium Chelates

The purpose of this study was to evaluate the enhancement profile of 1.0M gadobutrol (high concentration: HC) in comparison to 0.5M gadopentetate dimeglumine and gadoterate meglumine (low concentration: LC) in dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) of prostate. In total, 48 patients who were diagnosed with prostate cancer by radiologist were included. Each patient was examined after intravenous injection of 0.1 mmol/kg body weight contrast agent with flow rate of 1.5 (HC) or 3.0 mL/s (LC). Circular regions of interest were placed at prostate cancer (PCa) and normal peripheral zone (normal PZ) in DCE-MRI. The enhancement curves were calculated as a relative enhancement. Statistical analysis was performed by Mann-Whitney U test (p<0.05 were considered significant). As a result, the enhancement at first phase of HC was significantly lower compared with LC in PCa (HC, 0.47; LC, 0.85; p=0.029), and in normal PZ (HC, 0.12; LC, 0.22; p=0.033). The enhancement of HC in PCa was significantly higher compared with LC at late phase. Although not significant, a similar tendency was observed in normal PZ. The present study suggested that the enhancement profile with HC was higher at late phase but the rise of the enhancement curve with HC tended to be delayed.

Discrimination between malignant and benign mass-like lesions from breast dynamic contrast enhanced MRI: semi-automatic vs. manual analysis of the signal time-intensity curves.

Purpose: To investigate the performance of a new semi-automatic method for analyzing the signal time-intensity curve (TIC) obtained by breast dynamic contrast enhancement (DCE)-MRI.Methods: In the conventional method, a circular region of interest was drawn manually onto the map reflecting the maximum slope of increase (MSI) to delineate the suspicious lesions. The mean TIC was determined subjectively as one of three different wash-out patterns. In the new method, the lesion area was identified semi-automatically. The mean TIC was categorized quantitatively. In addition to the MSI, other quantitative parameters were calculated, including the signal intensity slope (SIslope), initial percentage of enhancement (Einitial), percentage of peak enhancement (Epeak), early signal enhancement ratio (ESER), and second enhancement percentage (SEP). The performances were compared with receiver operating characteristic (ROC) analysis and Wilcoxon's test.Results: For TIC categorization results, the diagnostic accuracy rates were 61.54% with the traditional manual method and 76.92% with the new method. For the mean MSI values from the manual method, the accuracy was 63.41%. For the mean TIC derived using the semi-automatic method, the diagnostic accuracy were 82.05% for SIslope, 67.31% for MSI, 61.53% for Einitial, 64.75% for Epeak, 64.74% for ESER, and 52.56% for SEP, respectively. For the lesion regions identified by the semi-automatic method, the diagnostic accuracy for above mentioned parameters were 80.13%, 69.87%, 61.54%, 63.47%, 64.74% and 55.13%, respectively.Conclusion: With respect to the analysis of TIC from breast DCE-MRI, the results demonstrated that the new method increased the diagnostic accuracy, and should be considered as a supplementary tool for distinguishing benign and malignant lesions.

Diffusion imaging study of the Corpus Callosum in bipolar disorder

Structural and diffusion imaging studies have provided some evidence of abnormal organization of Corpus Callosum (CC) in Bipolar Disorder (BD). Therefore, by using Diffusion Weighted Imaging (DWI), which allows to build subtle prediction models of fiber integrity for white matter (WM) tracts, this study aims to further explore the microstructure integrity of CC in BD patients compared to matched healthy controls. Twenty-four chronic patients with BD and 35 healthy controls were included in the study. Circular regions of interest were placed, on diffusion images, in the left and right side of callosal regions (i.e. rostrum/genu, anterior body, posterior body, splenium) and the Apparent Diffusion Coefficient (ADC) was then calculated. Significantly increased ADC values were found in right anterior body and in right splenium in BD patients compared to healthy controls (all p < 0.05, Bonferroni corrected). In this study, we found abnormally increased ADC callosal values in BD suggesting microstructural anomalies specifically in the right hemisphere. Interestingly, this finding further supports the presence of an altered inter-hemispheric communication between frontal and temporo-parietal association areas in patients with BD, which may ultimately result in clinical symptoms and cognitive deficits.

Performance of shear-wave elastography for breast masses using different region-of-interest (ROI) settings.

Background Various size and shape of region of interest (ROI) can be applied for shear-wave elastography (SWE). Purpose To investigate the diagnostic performance of SWE according to ROI settings for breast masses. Material and Methods To measure elasticity for 142 lesions, ROIs were set as follows: circular ROIs 1 mm (ROI-1), 2 mm (ROI-2), and 3 mm (ROI-3) in diameter placed over the stiffest part of the mass; freehand ROIs drawn by tracing the border of mass (ROI-M) and the area of peritumoral increased stiffness (ROI-MR); and circular ROIs placed within the mass (ROI-C) and to encompass the area of peritumoral increased stiffness (ROI-CR). Mean (Emean), maximum (Emax), and standard deviation (ESD) of elasticity values and their areas under the receiver operating characteristic (ROC) curve (AUCs) for diagnostic performance were compared. Results Means of Emean and ESD significantly differed between ROI-1, ROI-2, and ROI-3 ( P < 0.0001), whereas means of Emax did not ( P = 0.50). For ESD, ROI-1 (0.874) showed a lower AUC than ROI-2 (0.964) and ROI-3 (0.975) ( P < 0.002). The mean ESD was significantly different between ROI-M and ROI-MR and between ROI-C and ROI-CR ( P < 0.0001). The AUCs of ESD in ROI-M and ROI-C were significantly lower than in ROI-MR ( P = 0.041 and 0.015) and ROI-CR ( P = 0.007 and 0.004). Conclusion Shear-wave elasticity values and their diagnostic performance vary based on ROI settings and elasticity indices. Emax is recommended for the ROIs over the stiffest part of mass and an ROI encompassing the peritumoral area of increased stiffness is recommended for elastic heterogeneity of mass.

Influence of region-of-interest determination on measurement of signal-to-noise ratio in liver on PET images.

On 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET), signal-to-noise ratio in the liver (SNRliver) is used as a metric to assess image quality. However, some regions-of-interest (ROIs) are used when measuring the SNRliver. The purpose of this study is to examine the different ROIs and volumes of interest (VOIs) to obtain a reproducible SNRliver. This study included 108 patients who underwent 18F-FDG-PET/CT scans for the purpose of cancer screening. We examined four different ROIs and VOIs; a 3-cm-diameter and a 4-cm-diameter circular ROI and a 3-cm-diameter and a 4-cm-diameter spherical VOI on the right lobe of the patients' livers. The average of SUV (SUVmean), standard deviation (SD) of SUV (SUVSD), SNRliver and SD of the SNRliver obtained using ROIs and VOIs were then compared. Although the SUVmean was not different among the ROIs and VOIs, the SUVSD was small with a 3-cm-diameter ROI. The largest SUVSD was obtained with a 4-cm-diameter spherical VOI. The SNRliver and the SD of the SNRliver with a 4-cm-diameter spherical VOI were the smallest, while those with a 3-cm-diameter circular ROI were the largest. These results suggest that a small ROI may be placed on a relatively homogeneous region not representing whole liver unintentionally. The SNRliver varied according to the shape and size of ROIs or VOIs. A 4-cm-diameter spherical VOI is recommended to obtain stable and reproducible SNRliver.

Features of the normal choriocapillaris with OCT-angiography: Density estimation and textural properties.

The main objective of our work is to perform an in depth analysis of the structural features of normal choriocapillaris imaged with OCT Angiography. Specifically, we provide an optimal radius for a circular Region of Interest (ROI) to obtain a stable estimate of the subfoveal choriocapillaris density and characterize its textural properties using Markov Random Fields. On each binarized image of the choriocapillaris OCT Angiography we performed simulated measurements of the subfoveal choriocapillaris densities with circular Regions of Interest (ROIs) of different radii and with small random displacements from the center of the Foveal Avascular Zone (FAZ). We then calculated the variability of the density measure with different ROI radii. We then characterized the textural features of choriocapillaris binary images by estimating the parameters of an Ising model. For each image we calculated the Optimal Radius (OR) as the minimum ROI radius required to obtain a standard deviation in the simulation below 0.01. The density measured with the individual OR was 0.52 ± 0.07 (mean ± STD). Similar density values (0.51 ± 0.07) were obtained using a fixed ROI radius of 450 μm. The Ising model yielded two parameter estimates (β = 0.34 ± 0.03; γ = 0.003 ± 0.012; mean ± STD), characterizing pixel clustering and white pixel density respectively. Using the estimated parameters to synthetize new random textures via simulation we obtained a good reproduction of the original choriocapillaris structural features and density. In conclusion, we developed an extensive characterization of the normal subfoveal choriocapillaris that might be used for flow analysis and applied to the investigation pathological alterations.