Minimum Intensity Projection Research Articles

Application of compressed sensing using chirp encoded 3D GRE and MPRAGE sequences

AbstractAn implementation of Non‐Fourier chirp‐encoding in 3D Gradient Recalled Echo (GRE), susceptibility‐weighted imaging (SWI) and Magnetization Prepared Rapid Gradient Echo (MPRAGE) sequences is presented with compressive sensing reconstruction. 3D GRE and MPRAGE sequences were designed, in which the phase encoding (PE) direction was encoded with spatially selective chirp encoding Radio Frequency (RF) pulses, while the slice and the readout directions were Fourier encoded using gradients. During each excitation along the PE direction, a different spatially‐selective RF excitation pulse was used to encode the PE direction with a complete set of unitary chirp encoding basis. Multichannel compressive sensing reconstruction on the undersampled in vivo data demonstrated that images reconstructed from chirp encoded data were able to preserve the spatial resolution better than the Fourier encoding. The mean Structural Similarity (SSIM) across five subjects at the acceleration factor of 6, for chirp encoded MPRAGE was 0.934 compared to 0.912 for Fourier encoded MPRAGE. The implementation of prospective undersampling demonstrated the feasibility of using chirp encoding in clinical practice for accelerated imaging. The minimum intensity projection of the compressive sensing (CS) reconstructed susceptibility weighted images revealed that chirp encoding is able to delineate small vessels better than the Fourier encoding with the SSIM of 0.960 for chirp encoding compared to the SSIM of 0.949 for the Fourier encoding. Improved performance of chirp encoding for CS reconstruction and SWI, along with the feasibility of implementation makes them a practical candidate for clinical MRI scans.

Lamb Waves and Adaptive Beamforming for Aberration Correction in Medical Ultrasound Imaging.

Phase aberration in transcranial ultrasound imaging (TUI) caused by the human skull leads to an inaccurate image reconstruction. In this article, we present a novel method for estimating the speed of sound and an adaptive beamforming technique for phase aberration correction in a flat polyvinylchloride (PVC) slab as a model for the human skull. First, the speed of sound of the PVC slab is found by extracting the overlapping quasi-longitudinal wave velocities of symmetrical Lamb waves in the frequency-wavenumber domain. Then, the thickness of the plate is determined by the echoes from its front and back side. Next, an adaptive beamforming method is developed, utilizing the measured sound speed map of the imaging medium. Finally, to minimize reverberation artifacts caused by strong scatterers (i.e., needles), a dual probe setup is proposed. In this setup, we image the medium from two opposite directions, and the final image can be the minimum intensity projection of the inherently co-registered images of the opposed probes. Our results confirm that the Lamb wave method estimates the longitudinal speed of the slab with an error of 3.5% and is independent of its shear wave speed. Benefiting from the acquired sound speed map, our adaptive beamformer reduces (in real time) a mislocation error of 3.1, caused by an 8 mm slab, to 0.1 mm. Finally, the dual probe configuration shows 7 dB improvement in removing reverberation artifacts of the needle, at the cost of only 2.4-dB contrast loss. The proposed image formation method can be used, e.g., to monitor deep brain stimulation procedures and localization of the electrode(s) deep inside the brain from two temporal bones on the sides of the human skull.

Comparison of the dose on specific 3DCT images and the accumulated dose for cardiac structures in esophageal tumors radiotherapy: whether specific 3DCT images can be used for dose assessment?

BackgroundCardiac activity could impact the accuracy of dose assessment for the heart, pericardium and left ventricular myocardium (LVM). The purpose of this study was to explore whether it is possible to perform dose assessment by contouring the cardiac structures on specific three-dimensional computed tomography (3DCT) images to reduce the impact of cardiac activity.MethodsElectrocardiograph-gated 4DCT (ECG-gated 4DCT) images of 22 patients in breath-hold were collected. MIM Maestro 6.8.2 (MIM) was used to reconstruct specific 3DCT images to obtain the Maximal intensity projection (MIP) image, Average intensity projection (AIP) image and Minimum intensity projection (Min-IP) image. The heart, pericardium and LVM were contoured in 20 phases of 4DCT images (0, 5%... 95%) and the MIP, AIP and Min-IP images. Then, a radiotherapy plan was designed at the 0% phase of the 4DCT images, and the dose was transplanted to all phases of 4DCT to acquire the dose on all phases, the accumulated dose of all phases was calculated using MIM. The dose on MIP, AIP and Min-IP images were also obtained by deformable registration of the dose. The mean dose (Dmean), V5, V10, V20, V30 and V40 for the heart, pericardium and LVM in MIP, AIP and Min-IP images were compared with the corresponding parameters after dose accumulation.ResultsThe mean values of the difference between the Dmean in the MIP image and the Dmean after accumulation for the heart, pericardium and LVM were all less than 1.50 Gy, and the dose difference for the pericardium and LVM was not statistically significant (p > 0.05). For dose-volume parameters, there was no statistically significant difference between V5, V10, and V20 of the heart and pericardium in MIP, AIP, and Min-IP images and those after accumulation (p > 0.05). For the LVM, only in the MIP image, the differences of V5, V10, V20, V30 and V40 were not significant compared to those after dose accumulation (p > 0.05).ConclusionsThere was a smallest difference for the dosimetry parameters of cardiac structures on MIP image compared to corresponding parameters after dose accumulation. Therefore, it is recommended to use the MIP image for the delineation and dose assessment of cardiac structures in clinical practice.

Extracting more for less: multi-echo MP2RAGE for simultaneous T1 -weighted imaging, T1 mapping, mapping, SWI, and QSM from a single acquisition.

To demonstrate simultaneous T1 -weighted imaging, T1 mapping, mapping, SWI, and QSM from a single multi-echo (ME) MP2RAGE acquisition. A single-echo (SE) MP2RAGE sequence at 7 tesla was extended to ME with 4 bipolar gradient echo readouts. T1 -weighted images and T1 maps calculated from individual echoes were combined using sum of squares and averaged, respectively. ME-combined SWI and associated minimum intensity projection images were generated with TE-adjusted homodyne filters. A QSM reconstruction pipeline was used, including a phase-offsets correction and coil combination method to properly combine the phase images from the 32 receiver channels. Measurements of susceptibility, , and T1 of brain tissue from ME-MP2RAGE were compared with those from standard ME-gradient echo and SE-MP2RAGE. The ME combined T1 -weighted, T1 map, SWI, and minimum intensity projection images showed increased SNRs compared to the SE results. The proposed coil combination method led to QSM results free of phase-singularity artifacts, which were present in the standard adaptive combination method. T1 -weighted, T1 , and susceptibility maps from ME-MP2RAGE were comparable to those obtained from SE-MP2RAGE and ME-gradient echo, whereas maps showed increased blurring and reduced SNR. T1 , , and susceptibility values of brain tissue from ME-MP2RAGE were consistent with those from SE-MP2RAGE and ME-gradient echo. High-resolution structural T1 weighted imaging, T1 mapping, mapping, SWI, and QSM can be extracted from a single 8.5-min ME-MP2RAGE acquisition using a customized reconstruction pipeline. This method can be applied to replace separate SE-MP2RAGE and ME-gradient echo acquisitions to significantly shorten total scan time.

Blood Perfusion and Cellular Microstructural Changes Associated With Iron Deposition in Multiple Sclerosis Lesions

Background and Purpose: Susceptibility-weighted imaging (SWI) has emerged as a useful clinical tool in many neurological diseases including multiple sclerosis (MS). This study aims to investigate the relationship between SWI signal changes due to iron deposition in MS lesions and tissue blood perfusion and microstructural abnormalities to better understand their underlying histopathologies.Methods: Forty-six patients with relapsing remitting MS were recruited for this study. Conventional FLAIR, pre- and post-contrast T1-weighted imaging, SWI, diffusion tensor imaging (DTI), and dynamic susceptibility contrast (DSC) perfusion MRI were performed in these patients at 3T. The SWI was processed using both magnitude and phase information with one slice minimal intensity projection (mIP) and phase multiplication factor of 4. MS lesions were classified into 3 types based on their lesional signal appearance on SWI mIP relative to perilesional normal appearing white matter (peri-NAWM): Type-1: hypointense, Type-2: isointense, and Type-3: hyperintense lesions. The DTI and DSC MRI data were processed offline to generate DTI-derived mean diffusivity (MD) and fractional anisotropy (FA) maps, as well as DSC-derived cerebral blood flow (CBF) and cerebral blood volume (CBV) maps. Comparisons of diffusion and perfusion measurements between lesions and peri-NAWM, as well between different types of lesions, were performed.Results: A total of 137 lesions were identified on FLAIR in these patients that include 40 Type-1, 46 Type-2, and 51 Type-3 lesions according to their SWI intensity relative to peri-NAWM. All lesion types showed significant higher MD and lower FA compared to their peri-NAWM (P < 0.0001). Compared to Type-1 lesions (likely represent iron deposition), Type-2 lesions had significantly higher MD and lower FA (P < 0.001) as well as lower perfusion measurements (P < 0.05), while Type 3 lesions had significantly higher perfusion (P < 0.001) and lower FA (P < 0.05). Compared to Type-2, Type-3 lesions had higher perfusion (P < 0.0001) and marginally higher MD and lower FA (P < 0.05).Conclusion: The significant differences in diffusion and perfusion MRI metrics associated with MS lesions, that appear with different signal appearance on SWI, may help to identify the underlying destructive pathways of myelin and axons and their evolution related to inflammatory activities.

Impact of planned dose reporting methods on Gamma pass rates for IROC lung and liver motion phantoms treated with pencil beam scanning protons

PurposeThe purpose of this study is to evaluate the impact of two methods of reporting planned dose distributions on the Gamma analysis pass rates for comparison with measured 2D film dose and simulated delivered 3D dose for proton pencil beam scanning treatment of the Imaging and Radiation Oncology Core (IROC) proton lung and liver mobile phantoms.Methods and materialsFour-dimensional (4D) computed-tomography (CT) image sets were acquired for IROC proton lung and liver mobile phantoms, which include dosimetry inserts that contains targets, thermoluminescent dosimeters and EBT2 films for plan dose verification. 4DCT measured fixed motion magnitudes were 1.3 and 1.0 cm for the lung and liver phantoms, respectively. To study the effects of motion magnitude on the Gamma analysis pass rate, three motion magnitudes for each phantom were simulated by creating virtual 4DCT image sets with motion magnitudes scaled from the scanned phantom motion by 50, 100, and 200%. The internal target volumes were contoured on the maximum intensity projection CTs of the 4DCTs for the lung phantom and on the minimum intensity projection CTs of the 4DCTs for the liver phantom. Treatment plans were optimized on the average intensity projection (AVE) CTs of the 4DCTs using the RayStation treatment planning system. Plan doses were calculated on the AVE CTs, which was defined as the planned AVE dose (method one). Plan doses were also calculated on all 10 phase CTs of the 4DCTs and were registered using target alignment to and equal-weight-summed on the 50% phase (T50) CT, which was defined as the planned 4D dose (method two). The planned AVE doses and 4D doses for phantom treatment were reported to IROC, and the 2D-2D Gamma analysis pass rates for measured film dose relative to the planned AVE and 4D doses were compared. To evaluate motion interplay effects, simulated delivered doses were calculated for each plan by sorting spots into corresponding respiratory phases using spot delivery time recorded in the log files by the beam delivery system to calculate each phase dose and accumulate dose to the T50 CTs. Ten random beam starting phases were used for each beam to obtain the range of the simulated delivered dose distributions. 3D-3D Gamma analyses were performed to compare the planned 4D/AVE doses with simulated delivered doses.ResultsThe planned 4D dose matched better with the measured 2D film dose and simulated delivered 3D dose than the planned AVE dose. Using planned 4D dose as institution reported planned dose to IROC improved IROC film dose 2D-2D Gamma analysis pass rate from 92 to 96% on average for three films for the lung phantom (7% 5 mm), and from 92 to 94% in the sagittal plane for the liver phantom (7% 4 mm), respectively, compared with using the planned AVE dose. The 3D-3D Gamma analysis (3% 3 mm) pass rate showed that the simulated delivered doses for lung and liver phantoms using 10 random beam starting phases for each delivered beam matched the planned 4D dose significantly better than the planned AVE dose for phantom motions larger than 1 cm (p ≤ 0.04).ConclusionsIt is recommended to use the planned 4D dose as the institution reported planned dose to IROC to compare with the measured film dose for proton mobile phantoms to improve film Gamma analysis pass rate in the IROC credentialing process.

Effect of Slab Thickness on the Detection of Pulmonary Nodules by Use of CT Maximum and Minimum Intensity Projection.

OBJECTIVE. The purpose of this study was to investigate the effect of slab thickness on the detection of pulmonary nodules by use of maximum-intensity-projection (MIP) and minimum-intensity-projection (MinIP) to process CT images. MATERIALS AND METHODS. Chest CT data of 221 patients with pulmonary nodules were retrospectively analyzed. Nodules were categorized into two groups according to density: solid nodules (SNs) and subsolid nodules (SSNs). Pulmonary nodules were independently evaluated by two radiologists using axial CT images with 1-mm and 5-mm section thickness and MIP and MinIP images. MIP images for SN detection and MinIP images for SSN detection were separately reconstructed with four (5, 10, 15, 20 mm) and three (3, 8, 15 mm) slab thicknesses. The numbers and locations of detected nodules were recorded, and interobserver agreement was assessed. For each reader, the differences in nodule detection rates were evaluated in different series of images. RESULTS. Among the different series of images, interobserver agreements for detecting nodules were all good to excellent (κ ≥ 0.687). For total SNs and SNs with a diameter < 5 mm, detection rates on 10-mm MIP images were significantly higher than in other series of images (reader 1, 84.5% and 83.8%; reader 2, 83.6% and 82.2%). For total SSNs and SSNs < 5 mm, detection rates on 3-mm MinIP images were significantly higher than those in other series of images, except for 1-mm (reader 1, 93.3% and 78.6%; reader 2, 95.0% and 81.0%). CONCLUSION. Ten-millimeter MIP images are extremely efficient for detecting SNs. Three-millimeter MinIP images are more useful for visualizing SSNs, the efficiency being comparable to that achieved by use of 1-mm axial images.

COMPARATIVE ANALYSIS IMAGE RESULTS OF PANCREAS IN PORTAL VEIN PHASE ON CT SCAN ABDOMEN CONTRAST WITHOUT AND WITH MINIMUM INTENSITY PROJECTION IN CT SCAN 64 SLICE

Background: Minimum Intensity Projection is a post-proccesing technique on CT Scan that useful for showing structures with low Hounsfiled Unit (HU) values such as pancreas. To demonstrate the anatomy and pathology of the pancreatic organs, a contrast CT scan was performed on pancreatic phase but pancreatic phase was rarely used, so it was replaced by the portal venous phase, but this technique is still rarely used among the radiographers. Objective: This study aimed to prove the image of the portal venous pancreatic vein on contrast contrast CT scan by using minimum intensity projection (MinIP) on CT scan 64 slices will produce a more optimal image than without the minimum intensity projection (MinIP). Methods: This study is a retrospective study with an observational analytic method to assess differences of pancreatic image in contrasting contrast CT scans with and with MinIP reforms on CT 64 slice modalities Philips Briliance. 30 images as samples, with the criteria set by the researchers. The image will be post proccesing without and by using MinIP reformat. Image results will be evaluated by two radiologist, then the data obtained will be tabulated and processed using SPSS software version 17. Result: From this research obtained the result that MinIP reformat able to produce pancreas image more optimal than image without MinIP reformat on CT scan 64 slice and shows a significant difference. Overall assessment of the image has an improvement with the MinIP but for the homogeneity of pancreatic images decreased. Conclusions: There was a significant difference between pancreatic venous porta port results in contrasting CT scans of the abdomen without and with MinIP reformat.

GTV volume estimation using different mode of computer tomography for lung tumors in stereotactic body radiation therapy

Abstract Aim: To estimate the Gross Tumor Volume (GTV) using different modes (axial, helical, slow, KV-CBCT &amp; 4D-CT) of computed tomography (CT) in pulmonary tumors. Materials &amp; Methods: We have retrospectively included ten previously treated case of carcinoma of primary lung or metastatic lung using Stereotactic Body Radiation Therapy (SBRT) in this study. All the patients underwent 4 modes of CT scan Axial, Helical, Slow &amp; 4D-CT using GE discovery 16 Slice PET-CT scanner and daily KV-CBCT for the daily treatment verification. For standardization, all the patients underwent different modes of scan using 2.5 mm slice thickness, 16 detectors rows and field of view of 400mm. Slow CT was performed using axial mode scan by increasing the CT tube rotation time (typically 3 – 4 sec.) as per the breathing period of the patients. 4D-CT scans were performed and the entire respiratory cycle was divided into ten phases. Maximum Intensity Projections (MIP), Minimum Intensity Projections (MinIP) and Average Intensity Projections (AvIP) were derived from the 10 phases. GTV volumes were delineated for all the patients in all the scanning modes (GTVAX - Axial, GTVHL - Helical, GTVSL – Slow, GTVMIP -4DCT and GTVCB – KV-CBCT) in the Eclipse treatment planning system version 11.0 (M/S Varian Medical System, USA). GTV volumes were measured, documented and compared with the different modes of CT scans. Results: The mean ± standard deviation (range) for MIP, slow, axial, helical &amp; CBCT were 36.5 ± 40.5 (2.29 – 87.0), 35.38 ± 39.52 (2.1 – 82), 31.95 ± 37.29 (1.32 – 66.9), 28.98 ± 33.36 (1.01 – 65.9) &amp; 37.16 ± 42.23 (2.29 – 92). Overall underestimation of helical scan and axial scan compared to MIP is 21% and 12.5%. CBCT and slow CT volume has a good correlation with the MIP volume. Conclusion: For SBRT in lung tumors better to avoid axial and helical scan for target delineation. MIP is a still a golden standard for the ITV delineation, but in the absence of 4DCT scanner, Slow CT and KV-CBCT data may be considered for ITV delineation with caution.

Clinical Significance of Asymmetric Minimum Intensity Projection Images of Brain Magnetic Resonance Imaging in Children.

Background and PurposeThe susceptibility-weighted imaging form of brain MRI using minimum intensity projection (mIP) is useful for assessing traumatic brain injuries because it readily reveals deoxyhemoglobin or paramagnetic compounds. We investigated the efficacy of using this methodology in nontraumatic patients.MethodsWe retrospectively analyzed the asymmetric mIP findings in nontraumatic patients. Asymmetric mIP images were first verified visually and then using ImageJ software. We enrolled patients with a difference of >5% between hemispheres in ImageJ analysis. All patients underwent detailed history-taking and EEG, and asymmetric mIP findings were compared.ResultsThe visual analysis identified 54 pediatric patients (37 males and 17 females) with asymmetric mIP findings. Ten patients were excluded because they did not meet the ImageJ verification criteria. The 44 patients with asymmetry comprised 36 with epilepsy, 6 with headache, and 2 with cerebral infarction. Thirty-one of the 36 epileptic patients showed definite partial seizure activities in semiology, while the remaining patients did not demonstrate a history of partial seizure manifestations. The MRI findings were normal in all patients except for five with periventricular leukomalacia unrelated to seizure symptoms. There was agreement between mIP images and semiology in 29 (93.5%) of the 31 epileptic patients with focal signs, while the other 2 demonstrated discordance. Twenty (64.5%) of the 31 patients showed consistent EEG abnormalities.ConclusionsOur data suggest that asymmetric mIP findings are an excellent lateralizing indicator in pediatric patients with partial epilepsy.

Preliminary application of susceptibility weighted imaging in meningiomas

Objective To evaluate the preliminary application of susceptibility weighted imaging (SWI) in meningiomas. Methods Fifty meningioma patients, treated at Department of Neurosurgery of Nanjing Brain Hospital Affiliated to Nanjing Medical University between October 2015 and February 2018, were retrospectively enrolled into this study. All cases underwent brain CT, MRI and SWI scans preoperatively, and the minimum intensity projection (mIP) was obtained through processing basic SWI images by software. Compared with MRI and CT, intratumoral microhemorrhage, calcification and drainage vein in meningioma were analyzed in mIP and filtered phase imaging. Pathological examination was carried out after operation. Further comparative analysis was accomplished between microhemorrhagic group and non-microhemorrhagic group in imaging features and pathological indexes. Results Among the 50 meningioma patients examined by SWI, 7 (14%) had 24 intratumoral microhemorrhages; 24 (48%) had 47 intratumoral calcifications, including 31 calcifications that were consistent with CT and 16 which were not detected by CT; 16 (32%) clearly showed dominant draining veins originating from the tumor itself, consisting of 11 without peritumoral edema and 5 with peritumoral edema. The patients without peritumoral edema were more likely to form drainage veins than those with peritumoral edema [61%(11/18) vs. 16% (5/32), P=0.001]. All 50 patients were pathologically confirmed to have WHO Grade Ⅰ meningiomas. The edema index (EI), maximum edema width and Ki67 in the microhemorrhagic group were significant higher than those in non-microhemorrhagic group (all P 0.05). Conclusions Intratumoral microhemorrhage, microcalcification and drainage vein can be detected by SWI. Intratumoral hemorrhages infrequently occur in WHO Grade Ⅰ meningiomas. Microhemorrhagic meningiomas have higher Ki67 and more serious peritumoral edema than non-hemorrhagic ones. The efferent draining vein from meningioma itself may alleviate the formation of peritumoral edema. Key words: Meningioma; Calcinosis; Susceptibility weighted imaging; Microhemorrhage; Vein

Microvessels may Confound the "Swallow Tail Sign" in Normal Aged Midbrains: A Postmortem 7 T SW-MRI Study.

Susceptibility weighted imaging (SWI) plays a role in the differential diagnosis of Parkinson's disease, but lacks widespread acceptance in clinical routine. In a descriptive pilot study, we assessed hypointense microstructures of the normal substantia nigra pars compacta at ultrahigh-field strength for interpretation of the "swallow tail sign." Magnetic resonance imaging at 7 Tesla was performed in five postmortem samples obtained from subjects not affected by Parkinson's disease. Susceptibility weighted images, including minimum intensity projections, were created followed by consensus assessment for microvascular confound. Histological workup in this case-control study included iron and myelin staining. Seven Tesla SWI images from the reference cohort of nine living subjects, all of which showed a positive "swallow tail sign" in their midbrains, were assessed visually. All specimens showed microvessels running through the dorsal pars compacta and along the caudolateral circumference of the red nucleus. Hypointense imaging patterns in the medial part of the "swallow tail" were due to susceptibility effects of iron deposits and microvessels. In eight out of nine control subjects, one or more microvessels were detected medial to the dorsolateral nigral hyperintensity or at least unilaterally in the medial part of the "swallow tail." One microvessel crossing nigrosome 1 was found in two in-vivo cases. Both iron deposits and microvessels contribute to the hyposignal surrounding nigrosome 1 in susceptibility weighted imaging of normal aged midbrains at ultrahigh-field strength. When assessing the substantia nigra for the presence or absence of the "swallow tail sign," intrinsic vessels may be a sporadic confounder.

Iliopsoas snapping hip: improving the diagnostic value of magnetic resonance imaging with a novel parameter.

To illustrate an advanced imaging parameter that describes the course of the iliopsoas tendon, and evaluate its correlations with iliopsoas internal hip snapping syndrome. This retrospective cohort study reviewed hip MRI images of all patients seen by a single surgeon between January 2015 and March 2016. The comparison group included all patients with clinical internal hip snapping, versus the control group that did not. MRI images were processed using minimum intensity projection. Measurements obtained of the pelvis and course of the iliopsoas tendon included: pelvic incidence, coronal angle, and sagittal opening angle (SOA). Comparison of measurements between the groups was performed with Mann-Whitney U analysis and receiver operator curve (ROC) plotting, with a significance cutoff of p = 0.05. The control group (n = 85) and comparison group (n = 48) demonstrated no difference in age or gender. Pelvic incidence was similar [51.3 (±10.7) degrees control versus 52.2 (±7.7) degrees comparison (p = 0.36)], as was coronal angle [13.9 (±4.6) degrees control versus 14.8 (±4.8) degrees comparison (p = 0.15)]. There was a significant difference in SOA [137.0 (±5.9) degrees control versus 141.9 (±6.5) degrees comparison (p < 0.01)]. ROC analysis revealed SOA threshold of 140 degrees for clinical IP hip snapping (p < 0.01), with odds ratio 5.2 (2.4-11.3) for SOA > 140degrees. Iliopsoas hip snapping is often part of a more complex disease process. While challenging to diagnose, advanced imaging parameters, like the sagittal opening angle, relate with clinical pathology. The SOA offers diagnostic value, with a threshold of greater than 140 degrees significantly correlating with clinical presentation.

Early Clinical Outcome of the First Lung SBRT Program in Jordan: Importance of International Collaboration

Background: The stereotactic radiotherapy (SBRT) program was established at King Hussein Cancer Center (KHCC) in Jordan through cooperation with an internationally renowned institution MD Anderson Cancer Center (MDACC) in USA, and it went clinical in 2012. Until the present day, it stands as the only SBRT program in the entire country with patient population that has increased in the past few years due influx of refugees from regional conflicts. In this presentation, we will present the clinical outcome of our SBRT program. Methods: 17 patients treated to date in the SBRT service. All patients underwent 10-phase 4DCT and PET-CT scans. The internal target volume (ITV) was constructed from the minimum intensity projection (MIP) dataset and expanded, if needed, following PET findings. 5 mm margin added to create the PTV. A dose scheme of 48 Gy in 4 fractions or 50 Gy/4 fractions were used for all patients except for two patients who received 60 Gy in 8 fractions due to toxicity concerns. Lung heterogeneity correction was used during planning and treatment delivery was done on Elekta Precise Linear Accelerator and using CBCT imaging for positioning for every fraction. Follow- up done by performing CT chest 3 months after completion of SBRT, and CT/PET every 6 months in the two years, CT chest every 4-6 months thereafter, and keeping CT/PET whenever indicated. Results: All patients treated were males except one, with age ranging from 50-84 years old (mode of 79). All patients were unfit for surgery except for one who refused surgery. All patients except one are alive with only one patient recurred locally. One patient died not due to cancer. Conclusion: The newly established SBRT clinical service in our country, serves as the only such treatment of a population of 9.5 million including 2.5 million refugees. We have started recruiting inoperable lung patients to the service at a slow pace to gain more confidence and experience before admitting larger number of patients. Clinical results are encouraging with most showing tumor regression/complete response as of last follow-up. This model of collaboration between KHCC and MDACC represents a successful scientific collaboration between cancer centers in developed and developing countries that lead to effective and safe implementation of new techniques and procedures.

Characteristics of wooden intraocular foreign body by magnetic resonance imaging in rabbits.

ObjectiveIntraocular foreign body (IOFB), a frequent cause of ocular trauma, causes serious damage to the eyes. This study was designed to elaborate and compare the characteristics of different magnetic resonance imaging (MRI) sequences in detecting wooden IOFBs in rabbits.MethodsThe right vitreous of 24 healthy rabbits was randomly implanted with diverse wooden foreign bodies (diameter φ = 0.2 mm). The T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), proton density-weighted imaging (PDWI), and susceptibility-weighted imaging (SWI) sequences were applied individually 2 weeks after the implantation.ResultsIOFBs were detected as linear low signals on T1WI, T2WI, PDWI, and SWI (SWI image). The detectable rates of poplar wood with a length of 0.5 mm were 0%, 50%, 0%, and 67% for T1WI, T2WI, PDWI, and SWI, respectively. SWI and T2WI sequences exhibited higher sensitivity than T1WI and PDWI. The detectable rates of the first three SWI sequences (magnitude, phase, and SWI) were all 67%, which was higher than that of the minimum intensity projection sequence (33%).ConclusionMRI is practicable in the diagnosis of wooden IOFBs. SWI and T2WI are optimal for the integrated diagnosis of wooden IOFBs and could be used for diagnosis and immediate treatment.

Ultra-high speed visualization of a flash-boiling jet in a low-pressure environment

We visualize the flash-boiling atomization of liquid jets released into a low-pressure environment at frame rates of up to five million frames per second using a long distance microscope. Such temporal resolution allowed us to capture the details of the bubble expansion mechanism, responsible for the jet atomization, for the first time. We document an abrupt transition from a laminar to a fully external flashing jet by systematically reducing the ambient pressure. We perform experiments with different volatile liquids, ejected through micro-nozzles with different inner diameters. Surprisingly, minimum pixel intensity projections revealed spray angles close to θs ∼ 360° and speeds of bubble expansion up to 140 m/s. Particle tracking shows that ejected droplets achieve speeds much larger than the jet velocity and drop sizes order of magnitude smaller than the diameter of the nozzle. Furthermore, hole growth speeds measured on the bubble's film in combination with Taylor–Culick predictions suggest that the smallest droplet sizes are on the hundreds of nanometer or submicron range, which contravenes the general belief that flash-boiling atomization results in uniform drop sizes.

Cardiac-Sparing Whole Lung IMRT in Patients With Pediatric Tumors and Lung Metastasis: Final Report of a Prospective Multicenter Clinical Trial

A prospective clinical trial was conducted for patients undergoing cardiac sparing (CS) whole lung irradiation (WLI) using intensity modulated radiation therapy (IMRT). The 3 trial aims were (1) to demonstrate the feasibility of CS IMRT with real-time central quality control; (2) to determine the dosimetric advantages of WLI using IMRT compared with standard anteroposterior (AP) techniques; and (3) to determine acute tolerance and short-term efficacy after a protocol-mandated minimum 2-year follow-up for all patients. All patients underwent a 3-dimensional chest computed tomography scan and a contrast-enhanced 4-dimensional (4D) gated chest computed tomography scan using a standard gating device. The clinical target volume was the entire bilateral 3-dimensional lung volume, and the internal target volume was the 4D minimum intensity projection of both lungs. The internal target volume was expanded by 1cm to get the planning target volume. All target volumes, cardiac contours, and treatment plans were centrally reviewed before treatment. The different cardiac volumes receiving percentages of prescribed radiation therapy (RT) doses on AP and IMRT WLI plans were estimated and compared. The target 20 patients were accrued in 2years. Median RT dose was 15Gy. Real-time central quality assurance review and plan preapproval were obtained for all patients. WLI using IMRT was feasible in all patients. Compared with standard AP WLI, CS IMRT resulted in a statistically significant reduction in radiation doses to the whole heart, atria, ventricles, and coronaries. One child developed cardiac dysfunction and pulmonary restrictive disease 5.5years after CS IMRT (15Gy) and doxorubicin (375mg/m2). The 2- and 3-year lung metastasis progression-free survival was 65% and 52%, respectively. We have demonstrated the feasibility of WLI using CS IMRT and confirmed the previously reported advantages of IMRT, including superior cardiac protection and superior dose coverage of 4D lung volumes. Further studies are required to establish the efficacy and safety of this irradiation technique.

3D Black-Blood Luminal Angiography Derived from High-Resolution MR Vessel Wall Imaging in Detecting MCA Stenosis: A Preliminary Study

3D high-resolution vessel wall imaging is increasingly used for intracranial arterial diseases. This study compared the diagnostic performance of black-blood luminal angiography derived from 3D vessel wall imaging with source images of vessel wall imaging and TOF-MRA in detecting middle cerebral artery stenosis. Sixty-two patients with suspected MCA atherosclerosis underwent TOF-MRA, vessel wall imaging, and CTA. Intracranial black-blood luminal angiography was created from source images of vessel wall imaging using minimum intensity projection. The degree and length of MCA stenosis were measured on source images of vessel wall imaging, TOF-MRA, and black-blood luminal angiography and compared using CTA as a reference standard. The image quality of black-blood luminal angiography was diagnostic in most patients. The intra- and interobserver agreement for both stenosis degree and length measurements was excellent for black-blood luminal angiography. It was comparable with that of source images of vessel wall imaging in grading stenosis. Compared with TOF-MRA, black-blood luminal angiography showed significantly higher sensitivity for the detection of severe stenosis (89.3% versus 64.3%, P = .039) and higher specificity for the detection of occlusion (95.4% versus 84.6%, P = .039). Lesion length estimated on source images of vessel wall imaging was significantly greater than that measured by CTA and black-blood luminal angiography (P < .001 and P = .010). Black-blood luminal angiography is better than TOF-MRA in detecting severe stenosis and occlusion of the MCA. Compared with source images of vessel wall imaging, it is more accurate in evaluating stenosis length. Black-blood luminal angiography can be produced as a derivative from vessel wall imaging and implemented as an adjunct to vessel wall imaging and TOF-MRA without extra acquisition time.

4D Imaging Experience for Treatment of Lung SBRT

So far we have treated 17 patients at our centre since February 2017 using VMAT on Elekta Versa HD linacs. Patients: T stages, a mixture of T1a, T1b and T2a with an even mix of tumour location. Our standard protocol involves a free-breathing (no abdominal compression) 4DCT for planning from which we have generated phase based CT datasets including the average intensity projection (AVIP) which is used for export to the image verification CBCT system. 10 phase images, a MIP (maximum intensity projection), an AVIP and MIP (minimum intensity projection) are exported to the TPS for contouring and planning. The treatment verification process includes a day 0 check for patient position and clearance on the linac. This includes a 4DCBCT image of the patient to ensure tumour motion is the same as at the planning CT. On treatment days, patients receive a 4DCBCT followed by a 3DCBCT acquisition immediately prior to treatment. Following treatment another 3DCBCT is acquired to assess intra-fraction motion.

ESTIMATION OF SUBCARINAL ANGLE USING MINIMUM INTENSITY PROJECTION IN COMPUTED TOMOGRAPHY

Objectives: The main objective of the study was to determine the normal subcarinal angle (SCA) in an adult patient, to compare the relationship of SCA with patient gender and age, and to correlate the SCA with body mass index (BMI).Methods: A total of 193 subjects (109 males and 85 females) in the age group of 20–60 years scheduled for computed tomography thorax at the Department of Radiodiagnosis and Imaging, Kasturba Hospital, Manipal, were included in the study. Plain images were reconstructed into 1.4 mm reformatted image and processed into minimum intensity projection, and measurement was taken using angle tool. Mean and standard deviation was used to determine normal SCA, and independent t-test was used to compare the relationship of SCA with patient’s age and gender. “Pearson correlation” was used to correlate SCA with BMI.Results- The mean SCA of the adult patient was 69.75±3.38°. The mean SCA in female was 69.90±4.07° and in male was 69.63±2.75°. In the age group of 20–40 years, the mean SCA was 70.38±3.85°, and in the age group of 41–60 years, it was 69.25±2.88°.Conclusion: There was no relationship between SCA and patient’s gender; however, the mean SCA of the age group 20–40 was found greater than that of 41–60 which was statistically significant. BMI has no significant correlation with SCA.