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Fulltext Effects of different tube potentials and iodine concentrations on image enhancement, contrast-to-noise ratio and noise in micro-CT images: a phantom study

Abdul Razak HR, Shaffiq Said Rahmat SM, Md Saad WM

Quant Imaging Med Surg, 2013 Oct;3(5):256-61.
PMID: 24273743 DOI: 10.3978/j.issn.2223-4292.2013.10.04

The study aimed to investigate the effects of different tube potentials and concentrations of iodinated contrast media (CM) on the image enhancement, contrast-to-noise ratio (CNR) and noise in micro-computed tomography (µCT) images. A phantom containing of five polyethylene tube was filled with 2 mL of deionized water and iodinated CM (Omnipaque 300 mgI/mL) at four different concentrations: 5, 10, 15, and 20 mol/L, respectively. The phantom was scanned with a µCT machine (SkyScan 1176) using various tube potentials: 40, 50, 60, 70, 80, and 90 kVp, a fixed tube current; 100 µA, and filtration of 0.2 mm aluminum (Al). The percentage difference of image enhancement, CNR and noise of all images, acquired at different kVps and concentrations, were calculated. The image enhancement, CNR and noise curves with respect to tube potential and concentration were plotted and analysed. The highest image enhancement was found at the lowest tube potential of 40 kVp. At this kVp setting, the percentage difference of image enhancement [Hounsfield Unit (HU) of 20 mol/L iodine concentration over HU of deionized water] was 43%. By increasing the tube potential, it resulted with the reduction of HU, where only 17.5% different were noticed for 90 kVp. Across all iodine concentrations (5-20 M), CNR peaked at 80 kVp and then these values showed a slight decreasing pattern, which might be due insufficient tube current compensation. The percentage difference of image noise obtained at 40 and 90 kVp was 72.4%. Lower tube potential setting results in higher image enhancement (HU) in conjunction with increasing concentration of iodinated CM. Overall, the tube potential increment will substantially improve CNR and reduce image noise.

Matched MeSH terms: Iohexol
Acute Symptomatic Hyponatremia After Computed Tomography Renal Protocol

Lim LY, Mohd Firdaus CA, Fam XI, Goh EH

J Comput Assist Tomogr, 2017 Jan;41(1):65-66.
PMID: 27680416 DOI: 10.1097/RCT.0000000000000487

Computed tomography (CT) is a widely used imaging modality. Although hyponatremia after CT imaging is rare, its effects can be devastating. Hyperosmolar radiocontrast acts as effective osmoles and causes fluid migration from intracellular into extracellular compartment. Dilutional hyponatremia will ensue if translocation of fluid is in excess of diuresis. This case report detailed an unusual case of acute symptomatic hyponatremia after CT renal protocol and the treatments given after its recognition.

Matched MeSH terms: Iohexol/administration & dosage; Iohexol/adverse effects*
Fulltext Ureter triplication with contra-lateral partial duplex system

Mubarak MY, Zainun AR, Rohaya M

Med J Malaysia, 2009 Sep;64(3):236-7.
PMID: 20527276 MyJurnal

Ureteral triplication is a rare congenital anomaly of the urinary tract. We report a case of ureteral triplication with contralateral partial kidney duplication in a patient with right loin pain. The development and types of ureteral triplication and the features of type 2 ureteral triplication on intravenous urography and magnetic resonance urography are described.

Matched MeSH terms: Iohexol
Vessel density ratio: A novel approach to identify "culprit" coronary lesion by spiral computed tomography

Chin BS, Ong TK, Seyfarth TM, Liew CK, Chan WL, Rapaee A, et al.

J Comput Assist Tomogr, 2006 7 18;30(4):564-8.
PMID: 16845284

BACKGROUND AND OBJECTIVE: We hypothesized that a "culprit" lesion in acute coronary syndrome (ACS) should have low overall vessel lumen and plaque density on multidetector computed tomography-assisted coronary angiography (MDCTA) because of lower calcification and the presence of occlusive thrombus. However, thrombi and calcification both can themselves blur the demarcation between vessel wall and lumen. If we calculated a "vessel density ratio" (VDR) obtained by measuring the mean density of contrast-enhancement within a region of interest (ROI), which includes the vessel wall, lumen, plaque, and thrombus, and comparing that with the aortic root mean density acting as a reference point, this ratio may be more convenient, standardized, and reproducible to test the feasibility of VDR in identifying "culprit" lesions in ACS.
METHODS: Sixty-four patients-21 exertional angina; 17 unstable angina/non-ST elevation myocardial infarction (NSTEMI); 26 ST elevation myocardial infarction (STEMI)-provided 188 diseased segments on conventional angiography. All underwent MDCTA within a week of angiography. ROI was mapped out from maximum intensity projections of diseased segments in planar view.
RESULTS: One hundred seventy-four segments were evaluated. Patients who presented with ACS (STEMI and unstable angina/non-ST elevation myocardial infarction) had lower mean VDR compared to patients with exertional angina (0.58 vs. 0.66 vs. 0.81; P < 0.001). Culprit lesions in ACS patients also had the lowest mean VDR when compared to nonculprit lesions and lesions in patients without ACS (0.51 vs. 0.68 vs. 0.81; P < 0.001).
CONCLUSIONS: VDR is a new, convenient, and standardized approach in identifying "culprit" lesions by MDCTA.

Matched MeSH terms: Iohexol