Determination of Optimal Image Type and Lowest Detectable Concentration for Iodine Detection on a Photon Counting Detector-Based Multi-Energy CT System.

Published on Mar 9, 2018
· DOI :10.1117/12.2294949
Wei Zhou13
Estimated H-index: 13
(Mayo Clinic),
Rachel Schornak1
Estimated H-index: 1
(Mayo Clinic)
+ 6 AuthorsShuai Leng53
Estimated H-index: 53
(Mayo Clinic)
Sources
Abstract
Photon counting detector (PCD) based multi-energy CT is able to generate different types of images such as virtual monoenergetic images (VMIs) and material specific images (e.g., iodine maps) in addition to the conventional single energy images. The purpose of this study is to determine the image type that has optimal iodine detection and to determine the lowest detectable iodine concentration using a PCD-CT system. A 35 cm body phantom with iodine inserts of 4 concentrations and 2 sizes was scanned on a research PCD-CT system. For each iodine concentration, 80 repeated scans were performed and images were reconstructed for each energy threshold. In addition, VMIs at different keVs and iodine maps were also generated. CNR was measured for each type of images. A channelized Hotelling observer was used to assess iodine detectability after being validated with human observer studies, with area under the ROC curve (AUC) as a figure of merit. The agreement between model and human observer performance indicated that model observer could serve as an effective approach to determine optimal image type for the clinical practice and to determine the lowest detectable iodine concentration. Results demonstrated that for all size and concentration combinations, VMI at 70 keV had similar performance as that of threshold low images, both of which outperformed the iodine map images. At the AUC value of 0.8, iodine concentration as low as 0.2 mgI/cc could be detected for an 8 mm object and 0.5 mgI/cc for a 4 mm object with a 5 mm slice thickness.
📖 Papers frequently viewed together
4 Citations
28 Citations
References15
Newest
#1Orhan Ozguner (Case Western Reserve University)H-Index: 5
#2Amar Dhanantwari (Philips)H-Index: 9
Last. David W. Jordan (Case Western Reserve University)H-Index: 15
view all 6 authors...
This work evaluated the performance of a detector-based spectral CT system by obtaining objective reference data, evaluating attenuation response of iodine and accuracy of iodine quantification, and comparing conventional CT and virtual monoenergetic images in three common phantoms. Scanning was performed using the hospital's clinical adult body protocol. Modulation transfer function (MTF) was calculated for a tungsten wire and visual line pair targets were evaluated. Image noise power spectrum ...
28 CitationsSource
#1Shuai Leng (Mayo Clinic)H-Index: 53
#2Wei Zhou (Mayo Clinic)H-Index: 13
Last. Cynthia H. McCollough (Mayo Clinic)H-Index: 76
view all 9 authors...
Photon-counting computed tomography (PCCT) uses a photon counting detector to count individual photons and allocate them to specific energy bins by comparing photon energy to preset thresholds. This enables simultaneous multi-energy CT with a single source and detector. Phantom studies were performed to assess the spectral performance of a research PCCT scanner by assessing the accuracy of derived images sets. Specifically, we assessed the accuracy of iodine quantification in iodine map images a...
37 CitationsSource
#1Ralf Gutjahr (TUM: Technische Universität München)H-Index: 7
#2Ahmed F. HalaweishH-Index: 16
Last. Cynthia H. McColloughH-Index: 76
view all 10 authors...
ObjectivesThe purpose of this work was to measure and compare the iodine contrast-to-noise ratio (CNR) between a commercial energy-integrating detector (EID) computed tomography (CT) system and a photon-counting detector (PCD) CT scanner capable of human imaging at clinical dose rates, as well as to
111 CitationsSource
#1Chi Ma (Mayo Clinic)H-Index: 8
#2Lifeng Yu (Mayo Clinic)H-Index: 48
Last. Cynthia H. McCollough (Mayo Clinic)H-Index: 76
view all 6 authors...
Channelized Hotelling observer (CHO) models have been shown to correlate well with human observ- ers for several phantom-based detection/classification tasks in clinical computed tomography (CT). A large num- ber of repeated scans were used to achieve an accurate estimate of the model's template. The purpose of this study is to investigate how the experimental and CHO model parameters affect the minimum required number of repeated scans. A phantom containing 21 low-contrast objects was scanned o...
9 CitationsSource
#1Cynthia H. McCollough (Mayo Clinic)H-Index: 24
#2Shuai Leng (Mayo Clinic)H-Index: 53
Last. Joel G. Fletcher (Mayo Clinic)H-Index: 84
view all 4 authors...
The ability of dual- and multi-energy CT to differentiate materials of different effective atomic numbers makes possible several new and clinically relevant CT applications.
650 CitationsSource
#1Zhicong Yu (Mayo Clinic)H-Index: 11
#2Shuai Leng (Mayo Clinic)H-Index: 53
Last. Cynthia H. McCollough (Mayo Clinic)H-Index: 76
view all 11 authors...
X-ray computed tomography (CT) with energy-discriminating capabilities presents exciting opportunities for increased dose efficiency and improved material decomposition analyses. However, due to constraints imposed by the inability of photon-counting detectors (PCD) to respond accurately at high photon flux, to date there has been no clinical application of PCD-CT. Recently, our lab installed a research prototype system consisting of two x-ray sources and two corresponding detectors, one using a...
27 CitationsSource
#1Christopher P. Favazza (Mayo Clinic)H-Index: 24
#2Kenneth A. Fetterly (Mayo Clinic)H-Index: 18
Last. Beth A. Schueler (Mayo Clinic)H-Index: 32
view all 5 authors...
Evaluation of flat-panel angiography equipment through conventional image quality metrics is limited by the scope of standard spatial-domain image quality metric(s), such as contrast-to-noise ratio and spatial resolution, or by restricted access to appropriate data to calculate Fourier domain measurements, such as modulation transfer function, noise power spectrum, and detective quantum efficiency. Observer models have been shown capable of overcoming these limitations and are able to comprehens...
13 CitationsSource
#1Achille Mileto (NCSU: North Carolina State University)H-Index: 17
#2Daniele MarinH-Index: 39
Last. Giorgio AscentiH-Index: 13
view all 9 authors...
Our study shows that iodine quantification with dual-energy multidetector CT imaging can differentiate between clear cell and papillary renal cell carcinoma at a single imaging time point.
99 CitationsSource
#1Shuai Leng (Mayo Clinic)H-Index: 53
#2Lifeng Yu (Mayo Clinic)H-Index: 48
Last. Cynthia H. McCollough (Mayo Clinic)H-Index: 76
view all 6 authors...
Purpose: The purpose of this study was to investigate the correlation between model observer and human observer performance in CT imaging for the task of lesion detection and localization when the lesion location is uncertain. Methods: Two cylindrical rods (3-mm and 5-mm diameters) were placed in a 35 × 26 cm torso-shaped water phantom to simulate lesions with −15 HU contrast at 120 kV. The phantom was scanned 100 times on a 128-slice CT scanner at each of four dose levels (CTDIvol = 5.7, 11.4, ...
66 CitationsSource
#1Lifeng Yu (Mayo Clinic)H-Index: 48
#2Shuai Leng (Mayo Clinic)H-Index: 53
Last. Cynthia H. McCollough (Mayo Clinic)H-Index: 76
view all 6 authors...
Purpose: Efficient optimization of CT protocols demands a quantitative approach to predicting human observer performance on specific tasks at various scan and reconstruction settings. The goal of this work was to investigate how well a channelized Hotelling observer (CHO) can predict human observer performance on 2-alternative forced choice (2AFC) lesion-detection tasks at various dose levels and two different reconstruction algorithms: a filtered-backprojection (FBP) and an iterative reconstruc...
105 CitationsSource
Cited By5
Newest
Photon counting x-ray detectors (PCDs) with spectral capabilities have the potential to revolutionize computed tomography (CT) for medical imaging. The ideal PCD provides accurate energy information for each incident x-ray, and at high spatial resolution. This information enables material-specific imaging, enhanced radiation dose efficiency, and improved spatial resolution in CT images. In practice, PCDs are affected by non-idealities, including limited energy resolution, pulse pileup, and cross...
4 CitationsSource
#1Stefan Sawall (DKFZ: German Cancer Research Center)H-Index: 14
#2L. Klein (DKFZ: German Cancer Research Center)
Last. Marc Kachelrieß (DKFZ: German Cancer Research Center)H-Index: 3
view all 10 authors...
OBJECTIVE To evaluate the dual-energy (DE) performance and spectral separation with respect to iodine imaging in a photon-counting CT (PCCT) and compare it to dual-source CT (DSCT) DE imaging. METHODS A semi-anthropomorphic phantom extendable with fat rings equipped with iodine vials is measured in an experimental PCCT. The system comprises a PC detector with two energy bins (20 keV, T) and (T, eU) with threshold T and tube voltage U. Measurements using the PCCT are performed at all available tu...
Source
#1Thuy D Do (Heidelberg University)H-Index: 6
#2Stefan Sawall (DKFZ: German Cancer Research Center)H-Index: 14
Last. S Skornitzke (Heidelberg University)H-Index: 2
view all 10 authors...
An evaluation of energy thresholding and acquisition mode for metal artifact reduction in Photon-counting detector CT (PCD-CT) compared to conventional energy-integrating detector CT (EID-CT) was performed. Images of a hip prosthesis phantom placed in a water bath were acquired on a scanner with PCD-CT and EID-CT (tube potentials: 100, 120 and 140 kVp) and energy thresholds (above 55-75 keV) in Macro and Chess mode. Only high-energy threshold images (HTI) were used. Metal artifacts were quantifi...
Source
#1Chunling Zhang (SDU: Shandong University)
#2Ning Wang (SDU: Shandong University)
Last. Aimei Ouyang (SDU: Shandong University)H-Index: 2
view all 6 authors...
The aim of the present study was to examine the value of FORCE dual-energy CT in grading the clear cell renal cell carcinoma (ccRCC). A total of 35 cases of ccRCC were included. Hematoxylin and eosin staining was performed, and the cases were divided into low- (Fuhrman I-II) and high-grade (Fuhrman III-IV) groups. FORCE dual-energy CT parameters, including virtual network computing CT value (VNCV), iodine overlay value (IOV), mixed energy CT value (MEV), iodine concentration (IC), normalized iod...
1 CitationsSource
#1Wei Zhou (Mayo Clinic)H-Index: 13
#2Gregory Michalak (Mayo Clinic)H-Index: 12
Last. Shuai Leng (Mayo Clinic)H-Index: 53
view all 8 authors...
In addition to low-energy-threshold images (TLIs), photon-counting detector (PCD) computed tomography (CT) can generate virtual monoenergetic images (VMIs) and iodine maps. Our study sought to determine the image type that maximizes iodine detectability. Adult abdominal phantoms with iodine inserts of various concentrations and lesion sizes were scanned on a PCD-CT system. TLIs, VMIs at 50 keV, and iodine maps were generated, and iodine contrast-to-noise ratio (CNR) was measured. A channelized H...
2 CitationsSource