Weighted MR Images Research Articles

Comparison of Spleen Volumes Estimated Using Planimetry and Prolate Ellipsoid Methods on MRI in Myelofibrosis Patients

Background: Splenomegaly is one of the most characteristic features of myelofibrosis (MF) with significant impact on the quality of life of patients. About 10% of MF patients present with severely symptomatic splenomegaly at diagnosis; another 50% develop it within 4 years of diagnosis. Pharmaceutical drug trials aimed at treating myelofibrosis have assessment of spleen size as one of its key trial endpoints. While assessment of spleen size (volume) by palpation is routinely performed in the clinic, unfortunately, it is not a precise and reliable method, a key requirement in drug trials. Medical imaging methods such as magnetic resonance imaging (MRI) and computed tomography (CT) provide a non-invasive approach to assessment of spleen volume. Both modalities allow acquisition of cross sectional abdominal images and enable full anatomical coverage of the spleen. Due to radiation concerns, MRI is preferred over CT modality. There are two approaches for analyzing cross sectional images for estimation of spleen volume - the planimetry method, that involves delineating spleen contours on each spleen slice to estimate complete spleen volume and the prolate ellipsoid method, that approximates the spleen to an ellipsoid structure and estimates spleen volume by using the prolate ellipsoid method (described below). The prolate method is a simple and quick way to assess spleen size compared to the planimetry method. However, the former method provides an approximate estimate of spleen size. The goal of this study was to compare the prolate method with planimetry method for estimating spleen volume for use in pharmaceutical clinical trials.Methods: A retrospective assessment of spleen volume in N=30 subjects with confirmed diagnosis of myelofibrosis was performed. All measurements were performed on T2 weighted MR images (5mm slice thickness/0.0 gap), acquired on MRI scanners from different manufacturers. All images were assessed for image quality prior to including them in the analysis and images without any images quality issues were included in this study. The analysis methods and calculation used for estimating spleen volume were as below:•Planimetry: Volume = ∑ [(Region of interest outlining the spleen boundary per slice) x (Slice thickness)].•Prolate Ellipsoid: Volume = 0.52 x (Longest diameter of the spleen) x (longest perpendicular diameter on the same trans-axial slice) x (vertical distance between the most superior and most inferior margins of the spleen)Results: Spleen volume estimated by planimetry and prolate method was 2113cc±1612cc and 2186cc±1538cc (mean ± Standard Deviation [S.D.]). The range of planimetry spleen volumes in this study was 210 to 5750cc. A plot of spleen volumes estimated using planimetry and prolate method showed high correlation (R2 = 0.97) between the two methods, however, the volume variation tends to increase for large spleen sizes. The Bland-Altman plot for comparing the two methods showed mean difference in measures (73 cc) and difference variation (1 S.D. =300cc).Conclusions: Prolate method is a simple and useful alternate method for assessing spleen volume that does not require any specialized software for delineating spleen boundaries. However, the implementation of prolate method is operator dependent and requires precise positioning of digital calipers on images. Future work involves comparing the two methods with respect to change in spleen volume compared to baseline, an assessment performed routinely in pharmaceutical clinical trials. DisclosuresNo relevant conflicts of interest to declare.

Cerebrospinal fluid-suppressed T2 -weighted MR imaging at 7 T for human brain.

PurposeT2‐weighted lesional imaging is most commonly performed using inversion recovery turbo spin echoes. At 7 T, however, this acquisition is limited for specific absorption rate and resolution. This work describes and implements a method to generate CSF‐suppressed T2‐weighted imaging.MethodsThe strategy uses a driven equilibrium spin‐echo preparation within an inversion recovery with multiple 3D gradient‐echo imaging blocks. Images are combined using the self‐normalization approach, which achieves CSF suppression through optimized timing of individual blocks and minimizes sources of variation due to coil receptivity, T2 *, and proton density. Simulations of the magnetization‐prepared fluid‐attenuated inversion recovery gradient‐echo (MPFLAGRE) method over T1 and T2 relaxation values are performed, and in vivo demonstrations using an 8 × 2 transceiver array in healthy controls are shown.ResultsThe specific absorption rate of the calculated MPFLAGRE sequence is 11.1 ± 0.5 W (n = 5 volunteers), which is 74 ± 2% of the US Food and Drug Administration guidelines. This method acquires both contrasts for CSF suppression with detection of long T2 components and T2‐weighted imaging in a single acquisition. In healthy controls, the former contrast generates increased signal in the cortical rim and ependyma. A comparison is shown with a conventional 3D SPACE fluid‐attenuated inversion recovery acquisition, and sensitivity to pathology is demonstrated in an epilepsy patient.ConclusionAs applied with the 8 × 2 transceiver, the MPFLAGRE sequence generates both whole‐brain contrast suitable for lesional and T2‐weighted imaging at 7 T in fewer than 10 minutes within the US Food and Drug Administration's specific absorption rate guidelines.

Validity of apparent diffusion coefficient (ADC) value in diagnosis and follow-up of multiple sclerosis patients in different clinical subtypes

BackgroundMultiple sclerosis (MS) is a chronic disease with a wide range of pathologic changes that modify the apparent diffusion coefficient (ADC) value. Patients & methodsA prospective study included Forty two MS patients, underwent conventional and diffusion weighted MR imaging with ADC measurement in plaques and normally appearing white matter (NAWM), compared with normal white matter (NWM) of a control group (n = 21). They were followed-up six months later. ResultsSignificantly higher ADC values were found in acute and secondary progressive cases than relapsing remitting (RR) cases and all values were higher than in normal white matter. A higher ADC values was found in NAWM than control cases and in the newly developed plaques relative to old plaques in all types. A cut off ADC value 1.02 ± 0.20 × 10−3 mm2/sec was detected for MS diagnosis, a value 1.41 ± 0.10 × 10−3 mm2/sec to separate between acute and chronic RR cases and 1.2 ± 0.10 × 10−3 mm2/sec to differentiate chronic sub-types. ConclusionADC value has the validity in diagnosis and follow-up of MS patients with different clinical sub-types.

Effect of hydrocolloid and processing potentiality on water migration in apple jellies of Yinduqing cultivar

Numerous quality characteristics of food products are dependent on the microstructure and water status. In this study, LF-NMR and MRI techniques were applied for the evaluation of quality and water dynamics in apple jellies of Yinduqing cultivar during the course of 45 days storage. The present study investigated the impact of processing potentiality and formulation of hydrocolloid on water migration in jellies through non-destructive technique. The ingredients utilized in preparing the jelly were 500 mL juice, 400 g/kg sugar with 0, 2.0, 2.5 and 3.0% gelatin, respectively. Transverse relaxation time T2 exhibited three distinct water fractions (T21, T22, and T23) in the jelly samples during processing. Significant correlations were established between LF-NMR and physicochemical parameters. The macromolecular substance and gelatin influenced the water dynamics and caused a considerable variation in the T1 and T2 weighted MR images. Thus, the study revealed the feasibility of using non-destructive techniques in determining the dynamics of water within jelly products.

The Calcaneal Crescent in Patients With and Without Plantar Fasciitis: An Ankle MRI Study.

The bundled, crescent-shaped trabeculae within the calcaneal tuberosity-which we term and refer to here as the "calcaneal crescent"-may represent a structural adaption to the prevailing forces. Given Wolff law, we hypothesized that the calcaneal crescent would be more robust in patients with plantar fasciitis, a syndrome in part characterized by overload of the Achilles tendon-calcaneal crescent-plantar fascia system, than in patients without plantar fasciitis. MR images of 37 patients (27 women and 10 men; mean age ± SD, 51 ± 13 years; mean body mass index [BMI, weight in kilograms divided by the square of height in meters], 26.8 ± 6.3) referred for workup of foot or ankle pain were retrospectively evaluated by two blinded readers in this study. Patients were assigned to two groups: group A, which was composed of 15 subjects without clinical signs or MRI findings of Achilles tendon-calcaneal crescent-plantar fascia system abnormalities, or group B, which was composed of 22 patients with findings of plantar fasciitis. The thickness and cross-sectional area (CSA) of the Achilles tendon, calcaneal crescent, and plantar fascia were measured on proton density (PD)-weighted MR images. The entire crescent volume was manually measured using OsiriX software on consecutive sagittal PD-weighted images. Additionally, contrast-to-noise ratio (CNR) as a surrogate marker for trabecular density and the mean thickness of the calcaneal crescent were determined on PD-weighted MR images. The groupwise difference in the morphologic measurements were evaluated using ANOVA with BMI as a covariate. Partial correlation was used to assess the relationships of measurements for the group with plantar fasciitis (group B). Intraclass correlation coefficient (ICC) statistics were performed. Patients with plantar fasciitis had a greater CSA and volume of the calcaneal crescent and had lower CNR (i.e., denser trabeculae) than those without Achilles tendon-calcaneal crescent-plantar fascia system abnormalities (CSA, 100.2 vs 73.7 mm2, p = 0.019; volume, 3.06 vs 1.99 cm3, p = 0.006; CNR, -28.40 vs -38.10, p = 0.009). Interreader agreement was excellent (ICC = 0.85-0.99). In patients with plantar fasciitis, the calcaneal crescent is enlarged compared with those without abnormalities of the Achilles tendon-calcaneal crescent-plantar fascia system. An enlarged and trabeculae-rich calcaneal crescent may potentially indicate that abnormally increased forces are being exerted onto the Achilles tendon-calcaneal crescent-plantar fascia system.

Magnetic Resonance Imaging-Guided Drug Delivery to Breast Cancer Stem-Like Cells.

The feasibility of detecting breast cancer stem-like cells (BCSCs) with magnetic resonance imaging using extradomain-B of fibronectin (EDB-FN)-specific peptide (APTEDB )-conjugated thermally cross-linked superparamagnetic iron oxide nanoparticles (APTEDB -TCL-SPIONs) is previously demonstrated. Here, doxorubicin (Dox)-loaded APTEDB -TCL-SPIONs (Dox@APTEDB -TCL-SPIONs) are generated and their theranostic ability in a BCSC xenograft mouse model is assessed. The Dox@APTEDB -TCL-SPIONs enable more efficient delivery of Dox to tumors than nontargeted Dox@TCL-SPIONs. Much greater inhibition of BCSC tumor growth is observed after treatment with the Dox@APTEDB -TCL-SPIONs than with either Dox@TCL-SPIONs or free Dox. Hypointense signals are observed in the majority of the mice in postcontrast but not precontrast T2*-weighted MR images of tumors 7 days after treatment with Dox@APTEDB -TCL-SPIONs. An inverse correlation is observed between signal intensity and both EDB-FN expression and response to chemotherapy. The data indicate Dox@APTEDB -TCL-SPIONs can detect BCSCs within tumors by targeting EDB-FN-expressing cells. These nanoparticles thus have theranostic potential in breast cancer.

OA075] Prediction of recurrences using diffusion driven growth modelling for glioblastoma

Purpose Clinical target volume (CTV) for radiotherapy of glioblastoma is typically defined as an isotropic 2 cm expansion to the area of residual enhancement on T1 weighted MR imaging plus the surgical bed. Tumor growth models allow for incorporating the biological information about preferential spread along the white matter fibers in target definition. The aim of this study was to assess the value of an image driven CTV in the prediction of non-central recurrences. Methods Out of 56 glioblastoma patients treated with radiotherapy (dose 60 Gy in 30 fractions), five had recurrences extending outside the 95% isodose. Each patient’s brain was segmented into white matter, grey matter and cerebrospinal fluid (CSF). Anatomic boundaries were delineated manually. A reaction–diffusion growth model was used assuming uniform proliferation throughout the brain and a difference in white and grey matter diffusion of a factor of 10 with no migration across the barriers or in CSF. The volume of the image driven CTV (iCTV) was fixed to that of the standard CTV. The volumetric comparison was performed using the shortest distance (SD) between all surface points in the recurrence volume and respective CTV and iCTV. Results Three of five recurrences were distant, seperated at minimum of 3 cm from the resection cavity or the residual enhancement, in the temporal, parietal and frontal lobe. The median CTV and recurrence volume was 236 cm 3 (range: 175–240 cm 3 ) and 89 cm 3 (range: 1–112 cm 3 , respectively. The median SD from the recurrence volume decreased from 7.0 mm (range: 4.7–36.0 mm) for CTV to 5.5 mm (range: 2.9–28.1 mm) for iCTV indicating that iCTV was closer to the recurrence volume. However, distant recurrences were not included in either CTV or iCTV. Conclusions The image driven CTV appears promising in the prediction of marginal recurrences outside 95% isodose compared to standard CTV. However this population was limited in size and validation is warranted in a larger cohort.

Denoising of 3D magnetic resonance images with multi-channel residual learning of convolutional neural network.

To test if the proposed deep learning based denoising method denoising convolutional neural networks (DnCNN) with residual learning and multi-channel strategy can denoise three dimensional MR images with Rician noise robustly. Multi-channel DnCNN (MCDnCNN) method with two training strategies was developed to denoise MR images with and without a specific noise level, respectively. To evaluate our method, three datasets from two public data sources of IXI dataset and Brainweb, including T1 weighted MR images acquired at 1.5 and 3 T as well as MR images simulated with a widely used MR simulator, were randomly selected and artificially added with different noise levels ranging from 1 to 15%. For comparison, four other state-of-the-art denoising methods were also tested using these datasets. In terms of the highest peak-signal-to-noise-ratio and global of structure similarity index, our proposed MCDnCNN model for a specific noise level showed the most robust denoising performance in all three datasets. Next to that, our general noise-applicable model also performed better than the rest four methods in two datasets. Furthermore, our training model showed good general applicability. Our proposed MCDnCNN model has been demonstrated to robustly denoise three dimensional MR images with Rician noise.

Decreased apparent diffusion coefficient in the placentas of monochorionic twins with selective intrauterine growth restriction

ObjectivesThe apparent diffusion coefficient (ADC) was associated with the onset of intrauterine growth restriction in singleton pregnancies. However, the correlation of ADC with selective intrauterine growth restriction (sIUGR) of monochorionic (MC) twin pregnancies remained unknown. In this study, we aimed to evaluate the association of ADC with sIUGR in MC twin pregnancies by exploring diffusion weighted MR imaging (DWI). MethodsFifty-one MC twin pregnancies, consisting 19 cases of sIUGR and 32 cases without sIUGR, were re-analyzed by DWI. ADCs were quantitated from two regions of interest, surrounding the insertion of the umbilical cord of placenta for each twin. A rADC (ADClarger twin/ADCsmaller twin) in each placenta was also evaluated. Then ADCs and rADCs were compared between cases with and without sIUGR. ResultsThe ADC in cases with sIUGR was significantly decreased compared with cases without sIUGR (1.846 × 103 vs 2.471 × 103 mm2/s, p < 0.001). The rADC in cases with sIUGR was significantly increased (1.346 vs 1.053, p < 0.001). ConclusionsThe ADC decreases and the rADC increases in the placentas of MC twins with sIUGR, suggesting that diffusion in the placenta is restricted in pregnancies with sIUGR.

Histotripsy for Non-Invasive Ablation of Hepatocellular Carcinoma (HCC) Tumor in a Subcutaneous Xenograft Murine Model.

Histotripsy fractionates tissue through a mechanical, non-invasive ultrasonic ablation process that precisely controls acoustic cavitation while utilizing real-time ultrasound (US) imaging guidance. This study investigates the potential, feasibility and tumor volume reduction effects of histotripsy for liver cancer ablation in a subcutaneous in vivo murine Hepatocellular Carcinoma (HCC) model. Hep3B tumors were generated in the right flanks of 14 NSG and 7 NOD-SCID mice. The mice were grouped as follows: A (acute, NSG with n=9 treatment and n=1 control), B (chronic, NSG with n=2 treatment and n=2 control) and C (chronic NODSCID, with n=6 treatment and n=1 control). Treatment was performed when the tumor diameters reached >5 mm. 1-2 cycle histotripsy pulses at 100 Hz PRF (p- >30 MPa) were delivered using a custom built 1 MHz therapy transducer attached to a motorized positioner, which scanned the transducer focus to traverse the targeted tumor volume, guided by real-time US imaging. Tumor ablation effectiveness was assessed by obtaining T1, T2 and T2* weighted MR images. Post euthanasia, treated tumor, brain, and lung tissue samples were harvested for histology. Histology of acute group A showed fractionation of targeted region with a sharp boundary separating it from untreated tissue. Groups B and C demonstrated effective tumor volume reduction post treatment on MRI as the homogenate and edema were resorbed within 23 weeks. However, as the tumor was subcutaneous, it was not possible to set adequate treatment margin and since the mice were immune-compromised, residual viable tumor cells eventually developed into tumor regrowth at 3-9 weeks after histotripsy. Groups B and C showed no signs of metastasis in the lung and brain. Our study successfully demonstrated the potential of histotripsy for non-invasive HCC ablation in a subcutaneous murine model. Additional work is ongoing to study the response of histotripsy in immune-competent orthotopic liver tumor models.

The Role of Dynamic MRI with Diffusion Weighted Images in Evaluation of Portal Vein Thrombosis in Hepatic Patients

Background: hepatocellular carcinoma (HCC) is the fifth most common tumor worldwide and its incidence is increasing especially in western nations. HCC may be associated with portal vein thrombosis which could be either benign or malignant. Aim of the Work: to detect the role of diffusion MR imaging in the differentiation between benign and malignant portal vein thrombosis in patients with HCC. Materials and Methods: prospective study carried on 30 patients with liver cirrhosis with pathological or radiological proof of HCC, associated with visible portal vein thrombosis. Dynamic MRI examination and diffusion weighted imaging were performed for all patients. ADC values and ratios were calculated for both HCC and thrombus. Definite accepted radiological criteria were used as a standard of reference to detect the nature of the thrombus and discriminate between bland ones and neoplastic ones. Results: we found that the ratio between the ADC of the thrombus and ADC of the HCC was significantly different between the malignant and bland cohorts and a cutoff value of 1.25 for the ADC ratio helped in differentiation between malignant and benign portal vein thrombi with 85% sensitivity and 81% specificity. There was also obvious statistical significant difference between the ADC values of the bland and neoplastic thrombi. Conclusion: diffusion weighted MR imaging has a great role in differentiation between the benign and malignant portal vein thrombosis by measuring the ADC ratio between the thrombus and HCC.

The Role of Dynamic MRI with Diffusion Weighted Images in Evaluation of Portal Vein Thrombosis in Hepatic Patients

Background: hepatocellular carcinoma (HCC) is the fifth most common tumor worldwide and its incidence is increasing especially in western nations. HCC may be associated with portal vein thrombosis which could be either benign or malignant. Aim of the Work: to detect the role of diffusion MR imaging in the differentiation between benign and malignant portal vein thrombosis in patients with HCC. Materials and Methods: prospective study carried on 30 patients with liver cirrhosis with pathological or radiological proof of HCC, associated with visible portal vein thrombosis. Dynamic MRI examination and diffusion weighted imaging were performed for all patients. ADC values and ratios were calculated for both HCC and thrombus. Definite accepted radiological criteria were used as a standard of reference to detect the nature of the thrombus and discriminate between bland ones and neoplastic ones. Results: we found that the ratio between the ADC of the thrombus and ADC of the HCC was significantly different between the malignant and bland cohorts and a cutoff value of 1.25 for the ADC ratio helped in differentiation between malignant and benign portal vein thrombi with 85% sensitivity and 81% specificity. There was also obvious statistical significant difference between the ADC values of the bland and neoplastic thrombi. Conclusion: diffusion weighted MR imaging has a great role in differentiation between the benign and malignant portal vein thrombosis by measuring the ADC ratio between the thrombus and HCC.

Use-fullness of dynamic contrast-enhanced MR imaging and diffusion weighted MR imaging for differentiation of benign and malignant parotid tumors

Objectives: To evaluate the usefullness of dynamic contrast-enhanced MR Imaging (DCE-MRI) and diffusion weighted imaging (DWI) for differentiating benign from malignant parotid tumors. Methods: Prospectively,DCE-MRI and DWI were performed in 112 patients, with 148 confirmed parotid masses. The differential optimal thresholds were determined. Results: WConsidering tumors with time-intensity curve (TIC) Type C as malignant, sensitivity, specificity, accuracy were 95%, 76%, 79%, respectively. Considering ADC threshold values 0.709×10-3mm2 /s&lt;ADC&lt;0.948×10-3mm2 /s as malignant, sensitivity, specificity, accuracy were 75%, 78%, 78%, respectively. Considering TIC Type C and ADC values 0.709×10-3mm2 /s&lt;ADC&lt;0.948×10-3mm2 /s as malignant, sensitivity, specificity, accuracy were 75%, 91%, 89%, respectively. With threshold Kep&lt;1.118 min-1 and Ve &gt;0.315 between Warthin and malignant tumors, threshold Kep&gt;0.555 min-1 and Ve &lt;0.605 between pleomorphic adenomas and malignant tumors, sensitivity, specificity, accuracy for malignancy were 70% vs 90%, 96% vs 74%, 92% vs 80%, respectively. Conclusion: DCE-MRI and DWI provide more information in differentiating benign from malignant parotid tumors.

Manganese-porphyrin-enhanced MRI for the detection of cancer cells: A quantitative in vitro investigation with multiple clinical subtypes of breast cancer.

Magnetic resonance imaging (MRI) contrast agents (CAs) are chemical compounds that can enhance image contrast on T1- or T2- weighted MR image. We have previously demonstrated the potential of MnCl2, a manganese-based CA, in cellular imaging of breast cancer using T1-weighted MRI. In this work, we examined the potential of another class of manganese-based CAs, manganese porphyrins (MnPs), for sensitive cellular detection of multiple clinical subtypes of breast cancer using quantitative MRI. Using a clinical 3.0-T MRI scanner, the relaxivities of two MnPs, MnTPPS4 and MnTPPS3NH2, and conventional Gd-DTPA (control) were measured in ultrapure water and their T1 contrast enhancement patterns were characterized in multiple clinical subtypes of breast cancer. The toxicity of the three CAs was evaluated in vitro. Compared to Gd-DTPA, both MnTPPS3NH2 and MnTPPS4 enabled a more sensitive multi-subtype detection of four breast cell lines at doses that posed no cytotoxic effects, with MnTPPS3NH2 producing the greatest positive enhancement. The superior T1 enhancement capabilities of MnPs over Gd-DTPA are statistically significant and are likely due to their greater cellular uptake and relaxivities. The results demonstrate that multiple clinical subtypes of breast cancer can be imaged on a 3.0-T MRI scanner using MnPs as T1 cellular CAs.

Fibrosarcoma arising in the paranasal sinus: a clinicopathological and radiological analysis.

To analyze the clinicopathological features and the CT and MRI features of patients with paranasal sinus fibrosarcoma. Seven patients with surgically and pathologically confirmed paranasal sinus fibrosarcoma were enrolled. Their CT and MRI data and imaging features were retrospectively analyzed in detail. The study participants were two males and five females (median age, 43 years; range, 22-73 years). CT or MRI showed a well-defined (n = 5) or ill-defined (n = 2), irregular (n = 6) or oval (n = 1) mass, with heterogeneous (n = 7) density. The lesions were isointense (n = 4) or hypointense (n = 2) on T1weighted images, and showed heterogeneous (n = 6) mild hypointensity on T2weighted images. Expansive (n = 6) and osteolytic (n = 1) bone destruction were observed. The tumors showed marked heterogeneous delayed enhancement (n = 6) on contrast-enhanced MRI images. Paranasal sinus fibrosarcomas should be included in the differential diagnosis when a sinonasal neoplasm appears as a well- or ill-defined unilateral large irregular mass with characteristic mild hypointensity on T2weighted MR images and shows expansive or osteolytic bone destruction and a marked heterogeneous delayed contrast-enhancement pattern.

Potential fluorescence and magnetic resonance imaging modality using mixed lanthanide oxide nanoparticles.

Imaging is a very important technique in the diagnosis and treatment of cancer diseases. This study developed a dual modality (fluorescence/MR) imaging technique for cancer cell lines (HeLa) and T2-weighted phantom imaging by using a mixed lanthanide (Dy/Er/Tb) oxide nanoparticles. To further enhance the solubility, stability and biocompatibility of mixed lanthanide oxide, the nanoparticles were coated with folic acid as well as G4.5 PAMAM dendrimer. The coated nanoparticles were then compared, the later with results demonstrating pronounced effects in both T2 weighted phantom MR and fluorescence imaging of the cancer cell lines. Imaging enhancement was attributed to a synergistic effect of the fluorescent properties and higher water solubility of the PAMAM dendrimer when compared to the folic acid. Besides, mixed lanthanides of Dy and Tb were used for T2 weighted MR imaging, while mixed lanthanides of Er and Tb were used for fluorescence imaging in the near infrared and visible regions, and were synthesized in the facile composition control. Hence, the mixed lanthanide oxides are packed together, and stable, which is used to facilitate biomedical imaging in vitro. To conclude, the G4.5 PAMAM dendrimer coated mixed lanthanide oxide nanoparticles will be used for dual-modality (fluorescence/MR imaging) cancer cell line detection in both in vitro and in vivo study.

Practical implications of motion correction with motion insensitive radial k-space acquisitions in MRI.

To highlight specific instances when radial k-space acquisitions in MRI result in image artifacts and how to ameliorate such artifacts. We acquired axial T2weighted MR images on (1) the American College of Radiology (ACR) phantom and (2) a sedated sheep with rectilinear and multiblade radial k-space filling acquisitions. Images were acquired on four (2 × 1.5T and 2 × 3T) different MRI scanners. For the radial k-space acquisitions, we acquired images with and without motion correction. All images were visually inspected for the presence of artifact. Images collected via the conventional rectilinear method were of diagnostic quality and free of artifact. Both ACR and sheep images acquired with radial k-space acquisitions and motion correction suffered significant artifact at different slice locations, scan sessions and across all the four scanners. Severity of the artifact was associated with echo train length. However, the artifact was eliminated when motion correction was not employed. When little to no motion is present, the use of motion correction with radial k-space acquisitions can compromise image quality. However, image quality is quickly improved, and the artifact eliminated, by repeating the scan without motion correction or by using a conventional rectilinear alternative. Advances in Knowledge: By improving awareness and understanding of this artifact, MRI users will be able to adjust MRI protocols, resulting in more successful scanning sessions, better image quality, fewer call backs and increased diagnostic confidence.

Differentiating benign and malignant inflammatory breast lesions: Value of T2 weighted and diffusion weighted MR images

ObjectivesBenign and malignant inflammatory breast lesions demonstrate similar findings on both T2 weighted imaging (T2WI) and dynamic contrast enhanced (DCE) images. We hypothesized that benign inflammatory lesions might be differentiated form malignancies using a combination of apparent diffusion coefficient (ADC) values derived from diffusion weighted images (DWI) and T2WI. Materials and methodsWe retrospectively reviewed 162 patients undergoing breast MRI (T2WI, DWI and DCE images) between 2008 and 2015 who had breast lesions with high T2WI signal intensity (High T2 SI) including 14 benign inflammatory lesions, 69 benign non-inflammatory lesions, 16 malignant inflammatory lesions and 63 malignant non-inflammatory lesions. On the High T2 SI and low T2WI signal intensity (Low T2 SI) areas in these breast lesions, we calculated ADC values from b values of 0 and 1000 s/mm2. ResultsThe mean ADC values ± standard deviation (10−3 mm2/s) of the High T2 SI areas in benign inflammatory, benign non-inflammatory, malignant inflammatory and malignant non-inflammatory breast lesions were 0.75 ± 0.18, 1.77 ± 0.33, 2.06 ± 0.32 and 1.88 ± 0.41, respectively. Those of the Low T2 SI areas in benign inflammatory, benign non-inflammatory, malignant inflammatory and malignant non-inflammatory lesions were 0.89 ± 0.15, 1.31 ± 0.28, 0.87 ± 0.20 and 0.94 ± 0.27 respectively. ADC values of High T2 SI areas of the benign inflammatory lesions were significantly lower than those of benign non-inflammatory, malignant inflammatory, and malignant non-inflammatory lesions (p < 0.001). ADC values of Low T2 SI areas in benign inflammatory lesions were not significantly different from those of malignant inflammatory (p = 0.99) or malignant non-inflammatory lesions (p = 0.72). ConclusionFor breast lesions with High T2 SI, segmenting the High T2 SI for ADC mapping distinguishes benign from malignant inflammatory conditions. Using ADC mapping of the Low T2 SI areas will not result in this distinction.

Multiparametric MR imaging of peripheral zone prostate cancer: effect of postbiopsy hemorrhage on cancer detection according to Gleason score and tumour volume.

To evaluate effect of postbiopsy hemorrhage on detection of peripheral zone (PZ) prostate cancer by multiparametric MR imaging according to Gleason score and tumor volume. This retrospective study included 54 biopsy-proven prostate cancer patients (median age, 67.0 years) who underwent multiparametric MR imaging. Two independent readers evaluated each sextant of the PZ using the PI-RADS v2. One reader recorded the presence or absence of hemorrhage per sextant on T1weighted MR images. Areas under the receiver operating characteristic curves (AUCs) were used to evaluate cancer detection accuracy. Postbiopsy hemorrhage was noted in 122 (37.7%) of 324 sextants of all patients. There was no significant difference in the AUC for detection of cancer with Gleason score≥3+4 or volume≥0.5 ml between sextants with and without hemorrhage (with hemorrhage, reader 1, 0.83 for Gleason score≥3+4, 0.84 for tumor volume≥0.5 ml; reader 2, 0.74 for Gleason score≥3+4, 0.77 for tumor volume≥0.5 ml; without hemorrhage, reader 1, 0.86 for Gleason score≥3+4, 0.88 for tumor volume≥0.5 ml; reader 2, 0.79 for Gleason score≥3+4, 0.83 for tumor volume≥0.5 ml; p > 0.2 for all). Postbiopsy hemorrhage did not negatively affect the detection of clinically significant PZ prostate cancer on multiparametric MR imaging. Advances in knowledge: Under influence of postbiopsy hemorrhage, multiparametric MR can be useful for the detection of clinically significant PZ prostate cancer.

Orienting toward threat: Contributions of a subcortical pathway transmitting retinal afferents to the amygdala via the superior colliculus and pulvinar

Probabilistic diffusion tractography was used to provide the first direct evidence for a subcortical pathway from the retina to the amygdala, via the superior colliculus and pulvinar, that transmits visual stimuli signaling threat. A bias to orient toward threat was measured in a temporal order judgement saccade decision task, under monocular viewing, in a group of 19 healthy participants who also underwent diffusion weighted MR imaging. On each trial of the behavioural task a picture depicting threat was presented in one visual field and a competing non-threatening stimulus in the other. The onset interval between the two pictures was randomly varied and participants made a saccade toward the stimulus that they judged to have appeared first. The bias to orient toward threat was stronger when the threatening stimulus was in the temporal visual hemifield, suggesting that afferents via the retinotectal tract contributed to the bias. Probabalistic tractography was used to virtually dissect connections between the superior colliculus and the amygdala traversing the pulvinar. Individual differences in microstructure (fractional anisotropy) of the streamline predicted the magnitude of the bias to orient toward threat, providing supporting evidence for a functional role of the subcortical SC-amygdala pathway in processing threat in healthy humans.