Impact of a 4th Generation Iterative Reconstruction Technique on Image Quality in Low-Dose Computed Tomography of the Chest in Immunocompromised Patients

Laqmani, Azien; Buhk, Jan‐Hendrik; Henes, Frank Oliver; Klink, Thorsten; Sehner, Susanne; Schultzendorff, H. C. von; Nagel, H. D.; Adam, Gerhard; Regier, Marc

doi:10.1055/s-0033-1335577

Cited by 35 publications

(29 citation statements)

References 12 publications

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“…Accordingly, it should be as low as possible while maintaining constant diagnostic quality and follow the ALARA principle. Possible means of dose reduction are the reduction of both the tube current (mAs) and the tube voltage (kV) while using fully automatic dose modulation techniques and the implementation of iterative reconstruction methods [27].…”

Section: Ct Dosementioning

confidence: 99%

Imaging of Appendicitis in Adults

Karul

Berliner

Keller

et al. 2014

Fortschr Röntgenstr

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Three imaging modalities are available for the diagnosis of acute appendicitis: ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). Transabdominal ultrasound should be the first-line imaging test. Abdominal CT is superior to US and is required immediately in patients with atypical clinical presentation of appendicitis and suspected perforation. However, low-dose unenhanced CT is equal to standard-dose CT with intravenous contrast agents in the detection of five signs of acute appendicitis (thickened appendiceal wall more than 2?mm, cross-sectional diameter greater than 6?mm, periappendicitis, abscess, and appendicolith). MRI is necessary in pregnant women and young adults. This review illustrates the principles of state-of-the-art imaging techniques and their clinical relevance. Key Points: ??US is the basic diagnostic method in case of suspected appendicitis. ??CT is necessary in patients with atypical presentation of appendicitis. ??MRI should be the first-line imaging test in pregnant women. Citation Format: ??Karul M, Berliner C, Keller S et?al. Imaging of Appendicitis in Adults. Fortschr R?ntgenstr 2014; 186: 551???558

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Section: Ct Dosementioning

confidence: 99%

Imaging of Appendicitis in Adults

Karul

Berliner

Keller

et al. 2014

Fortschr Röntgenstr

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“…Many studies have been published within the last years reporting on noise reduction and improvement of low-contrast image quality due to IR in CT examinations of the abdomen [13], the thorax [14,15] and the heart [25 -27]. In recent studies by Utsunomiya et al and Laqmani et al, a progressive improvement of the CNR and subjective image quality in cardiac CT and lowdose chest CT was reported when using different levels of IR compared to FBP [28,29].…”

mentioning

confidence: 99%

Impact of Increasing Levels of Advanced Iterative Reconstruction on Image Quality in Low-Dose Cardiac CT Angiography

Kröpil

Bigdeli

Nagel

et al. 2014

Fortschr Röntgenstr

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Purpose: To investigate the effects of an advanced iterative reconstruction (IR) technique on subjective and objective image quality (IQ) in low-dose cardiac CT angiography (CCTA). Materials and Methods: 30 datasets of prospectively triggered ?step-and-shoot? CCTA scans acquired on a 256-slice CT scanner with optimized exposure settings were processed on a prototype IR system using filtered back-projection (FBP) and 4 levels of advanced IR (iDose4, Philips) providing incremental rates of IR (level 2, 4, 6, 7). In addition, the effects of different reconstruction kernels (semi-smooth [CB], standard with edge-enhancement [XCB]) and a ?multi-resolution? feature [MR] to preserve the noise power spectrum were evaluated resulting in a total of n?=?480 image sets. Contrast-to-noise ratios (CNR) were computed from regions of interest at 9 coronary locations. The subjective IQ was rated on a 4-point-scale with ?classic? image appearance and noise-related artifacts as main criteria. Results: At an effective dose of 1.7???0.7?mSv, the CNR significantly improved with every increasing level of IR (range: 14.2???27.8; p?

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“…By means of the dual‐domain processing, the

{iDose}^{4}

reconstruction algorithm can correct bias artifacts and maintain noise power spectrum constancy, while preserving spatial resolution. More details regarding the

{iDose}^{4}

reconstruction algorithm can be found in the technical paper provided by Philips and in the literature 3 , 9 , 10 , 11 …”

Section: Methodsmentioning

confidence: 99%

“…The

{iDose}^{4}

iterative reconstruction algorithm (Philips Medical, Cleveland, OH) has been commercially released as an artifact and radiation dose reduction tool, and mainly is used to improve image quality combined with dose reduction capabilities for diagnostic imaging purpose, while following the as‐low‐as‐reasonably‐achievable (ALARA) principle 3 , 9 , 10 , 11 . It has been reported from routine works of our clinical institutions that traditional diagnostic image quality definitions may not be realistic enough to determine the performance of the radiotherapy tasks, which certainly influence treatment planning accuracy.…”

Section: Introductionmentioning

confidence: 99%

A comparative study based on image quality and clinical task performance for CT reconstruction algorithms in radiotherapy

Dolly

Chen

et al. 2016

J Applied Clin Med Phys

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CT image reconstruction is typically evaluated based on the ability to reduce the radiation dose to as‐low‐as‐reasonably‐achievable (ALARA) while maintaining acceptable image quality. However, the determination of common image quality metrics, such as noise, contrast, and contrast‐to‐noise ratio, is often insufficient for describing clinical radiotherapy task performance. In this study we designed and implemented a new comparative analysis method associating image quality, radiation dose, and patient size with radiotherapy task performance, with the purpose of guiding the clinical radiotherapy usage of CT reconstruction algorithms. The iDose4iterative reconstruction algorithm was selected as the target for comparison, wherein filtered back‐projection (FBP) reconstruction was regarded as the baseline. Both phantom and patient images were analyzed. A layer‐adjustable anthropomorphic pelvis phantom capable of mimicking 38–58 cm lateral diameter‐sized patients was imaged and reconstructed by the FBP and iDose4 algorithms with varying noise‐reduction‐levels, respectively. The resulting image sets were quantitatively assessed by two image quality indices, noise and contrast‐to‐noise ratio, and two clinical task‐based indices, target CT Hounsfield number (for electron density determination) and structure contouring accuracy (for dose‐volume calculations). Additionally, CT images of 34 patients reconstructed with iDose4 with six noise reduction levels were qualitatively evaluated by two radiation oncologists using a five‐point scoring mechanism. For the phantom experiments, iDose4 achieved noise reduction up to 66.1% and CNR improvement up to 53.2%, compared to FBP without considering the changes of spatial resolution among images and the clinical acceptance of reconstructed images. Such improvements consistently appeared across different iDose4 noise reduction levels, exhibiting limited interlevel noise (<5 HU) and target CT number variations (<1 HU). The radiation dose required to achieve similar contouring accuracy decreased when using iDose4 in place of FBP, up to 32%. Contouring accuracy improvement for iDose4 images, when compared to FBP, was greater in larger patients than smaller‐sized patients. Overall, the iDose4 algorithm provided superior radiation dose control while maintaining or improving task performance, when compared to FBP. The reader study on image quality improvement of patient cases shows that physicians preferred iDose4‐reconstructed images on all cases compared to those from FBP algorithm with overall quality score: 1.21 vs. 3.15, p=0.0022. However, qualitative evaluation strongly indicated that the radiation oncologists chose iDose4 noise reduction levels of 3–4 with additional consideration of task performance, instead of image quality metrics alone. Although higher iDose4 noise reduction levels improved the CNR through the further reduction of noise, there was pixelization of anatomical/tumor structures. Very‐low‐dose scans yielded severe photon starvation artifacts, which decreased target visu...

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Impact of a 4th Generation Iterative Reconstruction Technique on Image Quality in Low-Dose Computed Tomography of the Chest in Immunocompromised Patients

Cited by 35 publications

References 12 publications

Imaging of Appendicitis in Adults

Imaging of Appendicitis in Adults

Impact of Increasing Levels of Advanced Iterative Reconstruction on Image Quality in Low-Dose Cardiac CT Angiography

A comparative study based on image quality and clinical task performance for CT reconstruction algorithms in radiotherapy

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