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Adam SZ, Rabinowich A, Kessner R, Blachar A. Spectral CT of the abdomen: Where are we now? Insights Imaging 2021; 12:138. [PMID: 34580788 PMCID: PMC8476679 DOI: 10.1186/s13244-021-01082-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 08/16/2021] [Indexed: 12/14/2022] Open
Abstract
Spectral CT adds a new dimension to radiological evaluation, beyond assessment of anatomical abnormalities. Spectral data allows for detection of specific materials, improves image quality while at the same time reducing radiation doses and contrast media doses, and decreases the need for follow up evaluation of indeterminate lesions. We review the different acquisition techniques of spectral images, mainly dual-source, rapid kV switching and dual-layer detector, and discuss the main spectral results available. We also discuss the use of spectral imaging in abdominal pathologies, emphasizing the strengths and pitfalls of the technique and its main applications in general and in specific organs.
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Affiliation(s)
- Sharon Z Adam
- Department of Diagnostic Radiology, Tel Aviv Sourasky Medical Center, 6 Weizmann St., 6423906, Tel Aviv, Israel. .,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Aviad Rabinowich
- Department of Diagnostic Radiology, Tel Aviv Sourasky Medical Center, 6 Weizmann St., 6423906, Tel Aviv, Israel.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Rivka Kessner
- Department of Diagnostic Radiology, Tel Aviv Sourasky Medical Center, 6 Weizmann St., 6423906, Tel Aviv, Israel.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Arye Blachar
- Department of Diagnostic Radiology, Tel Aviv Sourasky Medical Center, 6 Weizmann St., 6423906, Tel Aviv, Israel.,Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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Mohammadinejad P, Kwapisz L, Fidler JL, Sheedy SP, Heiken JP, Khandelwal A, Wells ML, Froemming AT, Hansel SL, Lee YS, Inoue A, Halaweish AF, McCollough CH, Bruining DH, Fletcher JG. The utility of a dual-phase, dual-energy CT protocol in patients presenting with overt gastrointestinal bleeding. Acta Radiol Open 2021; 10:20584601211030658. [PMID: 34377539 PMCID: PMC8323435 DOI: 10.1177/20584601211030658] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/15/2021] [Indexed: 12/03/2022] Open
Abstract
Background Due to their easy accessibility, CT scans have been increasingly used for
investigation of gastrointestinal (GI) bleeding. Purpose To estimate the performance of a dual-phase, dual-energy (DE) GI bleed CT
protocol in patients with overt GI bleeding in clinical practice and examine
the added value of portal phase and DE images. Materials and Methods Consecutive patients with GI bleeding underwent a two-phase DE GI bleed CT
protocol. Two gastroenterologists established the reference standard.
Performance was estimated using clinical CT reports. Three GI radiologists
rated confidence in GI bleeding in a subset of 62 examinations, evaluating
first mixed kV arterial images, then after examining additional portal
venous phase images, and finally after additional DE images (virtual
non-contrast and virtual monoenergetic 50 keV images). Results 52 of 176 patients (29.5%) had GI bleeding by the reference standard. The
overall sensitivity, specificity, and positive and negative predictive
values of the CT GI bleed protocol for detecting GI bleeding were 65.4%,
89.5%, 72.3%, and 86.0%, respectively. In patients with GI bleeding,
diagnostic confidence of readers increased after adding portal phase images
to arterial phase images (p = 0.002), without additional
benefit from dual energy images. In patients without GI bleeding, confidence
in luminal extravasation appropriately decreased after adding portal phase,
and subsequently DE images (p = 0.006, p =
0.018). Conclusion A two-phase DE GI bleed CT protocol had high specificity and negative
predictive value in clinical practice. Portal venous phase images improved
diagnostic confidence in comparison to arterial phase images alone.
Dual-energy images further improved radiologist confidence in the absence of
bleeding.
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Affiliation(s)
| | - Lukasz Kwapisz
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA
| | - Jeff L Fidler
- Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA
| | - Shannon P Sheedy
- Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA
| | - Jay P Heiken
- Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA
| | | | - Michael L Wells
- Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA
| | - Adam T Froemming
- Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA
| | - Stephanie L Hansel
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA
| | - Yong S Lee
- Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA
| | - Akitoshi Inoue
- Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA
| | | | | | - David H Bruining
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA
| | - Joel G Fletcher
- Department of Radiology, Mayo Clinic Minnesota, Rochester, MN, USA
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Kahn J, Fehrenbach U, Böning G, Feldhaus F, Maurer M, Renz D, Streitparth F. Spectral CT in patients with acute thoracoabdominal bleeding-a safe technique to improve diagnostic confidence and reduce dose? Medicine (Baltimore) 2019; 98:e16101. [PMID: 31232952 PMCID: PMC6636944 DOI: 10.1097/md.0000000000016101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Computed tomography (CT) protocols for the detection of bleeding sources often include unenhanced CT series to distinguish contrast agent extravasation from calcification. This study evaluates whether virtual non-contrast images (VNC) can safely replace real non-contrast images (RNC) in the search for acute thoracoabdominal bleeding and whether monoenergetic imaging can improve the detection of the bleeding source.The 32 patients with active bleeding in spectral CT angiography (SCT) were retrospectively analyzed. RNC and SCT series were acquired including VNC and monoenergetic images at 40, 70, and 140 keV. CT numbers were measured in regions of interest (ROIs) in different organs and in the bleeding jet for quantitative image analysis (contrast-to-noise ratios [CNR] and signal-to-noise ratio [SNR]). Additionally, 2 radiologists rated detectability of the bleeding source in the different CT series. Wilcoxon rank test for related samples was used.VNC series suppressed iodine sufficiently but not completely (CT number of aorta: RNC: 33.3±12.3, VNC: 44.8 ± 9.5, P = .01; bleeding jet: RNC: 43.1 ± 16.9, VNC: 56.3 ± 16.7, P = .02). VNC showed significantly higher signal-to-noise ratios than RNC for all regions investigated. Contrast-to-noise ratios in the bleeding jet were significantly higher in 40 keV images than in standard 140 keV images. The 40 keV images were also assigned the best subjective ratings for bleeding source detection.VNC can safely replace RNC in a CT protocol used to search for bleeding sources, thereby reducing radiation exposure by 30%. Low-keV series may enhance diagnostic confidence in the detection of bleeding sources.
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Affiliation(s)
| | | | | | | | - Martin Maurer
- Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, University of Bern, Bern
| | - Diane Renz
- Department of Radiology, University of Jena, Jena
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