Color Intensity Projections Research Articles

Summarizing the 4D image stack of ultrafast dynamic contrast enhancement MRI of breast cancer in 3D using color intensity projections.

Each ultrafast dynamic contrast-enhanced (DCE) MRI sequence for breast cancer generates thousands of images in a 4D stack that need to be reviewed by a radiologist. To assess whether color intensity projections (CIP) effectively summarizes-using only the time of arrival (ToA) and amount of signal enhancement (AoE) of the contrast agent-the thousands of ultrafast images. Retrospective cohort clinical trial. The study included 89 patients who had been scanned with an MRI beast protocol, of which 26 had breast cancer and 63 did not. The 115-second ultrafast DCE sequence at 3T acquired 19 consecutive frames every 4.26 seconds with 152 slices per frame, yielding a 4D stack with 2888 2D images for each of water and fat. For each slice of the water 4D stack a single CIP image was generated that encoded the ToA in the hue (red, orange, yellow, green, cyan, blue) and AoE in the brightness. Each of three experienced radiologists assigned a Breast Imaging and Reporting Data System (BI-RADS) score for each patient, first using only the CIP images, and subsequently using both CIP and the full 4D stack. The one-sided Fisher's exact test was used to determine statistical significance of both the sensitivity and specificity between the CIP alone and the CIP plus 4D stack. All malignancies were detected using only CIP by at least one of the radiologists. The CIP and CIP+4D sensitivities for reader 1 were 96% and 96% (P = 0.57), specificities were 59% and 65% (P = 0.29). For reader 2, the values were 96% and 100% (P = 0.51) with 62% and 71% (P = 0.17). For reader 3 the values were 92% and 96% (P = 0.50) with 51% and 62% (P = 0.07). With a 95% sensitivity, CIP provides an effective summary of ultrafast DCE images of breast cancer. 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1391-1399.

Verification of Intrafraction Motion using Cine MV and Color Intensity Projections

Verification of Intrafraction Motion using Cine MV and Color Intensity Projections

SU‐GG‐J‐179: The Errors in Determining Lung Tumor ITV From Time Resolved Image Reconstruction

Purpose: We have reported that the maximum intensity projection (MIP) of lung tumor determined from time resolved image modalities, such as 4DCT, may be inaccurate because of the patient breathing variability. Nevertheless, the MIP is often regarded as an overestimation of the internal target volume (ITV) and average intensity projection (AIP) is used for contouring. We created AIPs and their colorized presentation, color intensity projections (CIP), from dynamic MRIs and determined their dependency on respiratory variability and tumor size. Method and Materials: Low temporal resolution images in the superior/inferior direction were reconstructed from dynamic MRIs with high temporal resolution in the same direction. The reconstruction, referred as redCAM, used 4D‐CT time resolving methods with synchronizing to the internal region of interest (ROI). CIP and AIP were reconstructed based on the probability of a certain position being occupied by the tumor. These two parameters of redCAM were analyzed as a function of respiratory variability, which was defined as the average of the standard deviation in the maximal and minimal amplitude displacements. Results:_The error between AIP, MIP and CIP are strongly dependent on the percentage of CIP. Smaller errors were observed with lower percentage CIPs. The MIP derived from redCAM is closer to the 10% CIP instead of the MIP of the real time image, which is 0% CIP. The error of AIP and MIP is fit well as a quadratic function of the respiratory variability for given tumor size, indicating accelerated increase in the error with variability. Conclusion: AIP and MIP are commonly used in lung radiation therapy with 4DCT simulation. However, their accuracy is affected by the patient respiratory variability and tumor size. Our study provides a formula to include these uncertainties into the PTV.

Color Intensity Projections: A Simple Way to Display Changes in Astronomical Images

ABSTRACTTo detect changes in repeated astronomical images of the same field of view, a common practice is to stroboscopically switch between the images. Using this method, objects that are changing in location or intensity between images are easier to see because they are constantly changing. A novel display method, called arrival time color intensity projections, is presented that combines any number of gray‐scale images into a single‐color image on a pixel‐by‐pixel basis. Any values that are unchanged over the gray‐scale images look the same in the color image. However, pixels that change over the gray‐scale image have a color saturation that increases with the amount of change, and a hue that corresponds to the timing of the changes. Thus, objects moving in the gray‐scale images change from red to green to blue as they move across the color image. Consequently, moving objects are easier to detect and assess on the color image than on the gray‐scale images. A sequence of images of a comet plunging into the Sun taken by the Solar and Heliospheric Observatory (SOHO; NASA/ESA), and Hubble Space Telescope images of a trans‐Neptunian object, are used to demonstrate the method.

Reproducibility of target volumes generated using uncoached 4-dimensional CT scans for peripheral lung cancer

Background4-dimensional CT (4DCT) scans are increasingly used to account for mobility during radiotherapy planning. As variations in respiratory patterns can alter observed motion, with consequent changes in the generated target volumes, we evaluated the reproducibility of 4D target volumes generated during repeat uncoached quiet respiration.MethodsA retrospective analysis was performed on two successive scans (4DCT1 and 4DCT2) generated at the same scanning session for 26 patients with peripheral lung cancer treated with stereotactic radiotherapy (SRT). The volume and position of planning target volumes (PTV4DCT1 and PTV4DCT2) contoured on both scans were compared, and a dosimetric analysis performed. A SRT plan optimized for each PTV was sequentially applied to the other PTV, and coverage by the 80% isodose was evaluated. Color intensity projections (CIP) were used to evaluate regions of underdosage.ResultsNo significant volumetric differences were observed between the two PTVs (t-Test p = 0.60). The average displacement of the center of mass between corresponding PTVs was 1.4 ± 1.0 mm, but differences in position were 2.0 mm or greater in 5 cases (19%). Coverage of both PTVs by the 80% prescription isodose exceeded 90% for all but one patient. For the latter, the prescription isodose covered only 82.5% of PTV4DCT1. CIP analysis revealed that the region of underdosage was an end-inspiratory position occupied by the tumor for only 10–20% of the respiratory cycle.ConclusionIn nearly all patients with stage I lung cancer, the PTV derived from a single uncoached 4DCT achieves dosimetric coverage that is similar to that achieved using two such consecutive scans.

Color intensity projections: A rapid approach for evaluating four-dimensional CT scans in treatment planning

Four-dimensional computerized tomography scans (4DCT) enable intrafractional motion to be determined. Because more than 1500 images can be generated with each 4DCT study, tools for efficient data visualization and evaluation are needed. We describe the use of color intensity projections (CIP) for visualizing mobility. Four-dimensional computerized tomography images of each patient slice were combined into a CIP composite image. Pixels largely unchanged over the component images appear unchanged in the CIP image. However, pixels whose intensity changes over the phases of the 4DCT appear in the CIP image as colored pixels, and the hue encodes the percentage of time the tissue was in each location. CIPs of 18 patients were used to study tumor and surrogate markers, namely the diaphragm and an abdominal marker block. Color intensity projections permitted mobility of high-contrast features to be quickly visualized and measured. In three selected expiratory phases ("gating phases") that were reviewed in the sagittal plane, gating would have reduced mean tumor mobility from 6.3 +/- 2.0 mm to 1.4 +/- 0.5 mm. Residual tumor mobility in gating phases better correlated with residual mobility of the marker block than that of the diaphragm. CIPs permit immediate visualization of mobility in 4DCT images and simplify the selection of appropriate surrogates for gated radiotherapy.

Use of Color Intensity Projections (CIP) for 4D Respiration-Gated Radiotherapy (RGRT)

Use of Color Intensity Projections (CIP) for 4D Respiration-Gated Radiotherapy (RGRT)