Assessment of thermal sensitivity of CT during heating of liver: an<i>ex vivo</i>study

Pandeya, G. D.; Greuter, Marcel J W; Schmidt, Bernhard; Flohr, Thomas; Oudkerk, Matthijs

doi:10.1259/bjr/23942179

Cited by 19 publications

(17 citation statements)

References 30 publications

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“…Hence, when the PAA phantom was scanned at higher temperature, the thermally induced reduction in electron density was expected to occur although there was no change in the atomic composition. A CT thermal sensitivity of -0.521 ± 0.061 HU/ C (R 2 ¼ 0.998) has been found using liver tissue equivalent PAA phantom, which was in accordance to the CT thermal sensitivities of ex-vivo bovine liver (-0.60 ± 0.026 and -0.65 ± 0.05 HU/ C) [33,34] and swine liver (-0.54 ± 0.03 and -0.52 ± 0.02 HU/ C) carried out in other studies [8,35]. The obtained CT thermal sensitivity was also in agreement with the values found using swine muscle tissue and water equivalent phantom [36].…”

Section: Discussionsupporting

confidence: 88%

“…Thermal-induced coagulative necrosis of the tissue is achieved above 56 C where a complete protein denaturation occurs [7]. Hence, the tumor tissue should be heated to more than 56 C while the surrounding healthy tissues and blood vessels should be lower than 40 C during the hepatic RFA [8]. Failure to control the temperature distribution during hepatic RFA may cause incomplete tumor ablation or thermal damage to the surrounding structures.…”

Section: Introductionmentioning

confidence: 99%

“…Although invasive interstitial thermometry can be used to monitor the temperature of the ablation zone, this method can only be performed at a limited points in the liver and it is not clinically practical [12,13]. Therefore, several noninvasive methods such as magnetic resonance imaging (MRI)-based thermometry, ultrasound thermometry, microwave-based thermometry and CT-based thermometry are being explored for accurate temperature assessment in clinical application [8,14]. However, these methods struggle some constraints which restrict their feasibility on hepatic RFA.…”

Section: Introductionmentioning

confidence: 99%

“…However, these methods struggle some constraints which restrict their feasibility on hepatic RFA. Ultrasound-based and microwave-based thermometry are not favored as these methods are vulnerable to motion and mis-registration artifacts in moving and refilling organs such as liver [8]. On the other hand, MRI-based thermometry has been regarded as the most promising noninvasive method for temperature mapping.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Experimental assessment on feasibility of computed tomography-based thermometry for radiofrequency ablation on tissue equivalent polyacrylamide phantom

Tan

Mohamad

Wong

et al. 2019

International Journal of Hyperthermia

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Experimental assessment on feasibility of computed tomography-based thermometry for radiofrequency ablation on tissue equivalent polyacrylamide phantom

Tan

Mohamad

Wong

et al. 2019

International Journal of Hyperthermia

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“…Based on a previous study [21], the FUS marks at muscle tissue are expected to be oval in shape with a bright rim on T2W MRI. In addition, the heated tissues are observed as a hypodense area on CT images [22]. These properties were used to guide delineation of the contours of the regions-of-interest (ROIs).…”

Section: Methodsmentioning

confidence: 99%

Quantitative evaluation of internal marks made using MRgFUS as seen on MRI, CT, US, and digital color images – A pilot study

et al. 2014

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This pilot study compared the detectability of internal thermal marks produced with MRI-guided focused ultrasound (MRgFUS) on MRI, computed tomography (CT), ultrasonography (US), and color images from digital scanning. Internal marks made using MRgFUS could potentially guide surgical, biopsy or radiotherapy procedures. New Zealand White rabbits (n = 6) thigh muscle were marked using a Philips MRgFUS system. Before and after sonications, rabbits were imaged using T1- and T2-weighted MRI. Then rabbits were sacrificed and imaging was performed using CT and US. After surgical excision specimens were scanned for color conspicuity analysis. Images were read by a radiologist and quantitative analysis of signal intensity was calculated for marks and normal muscle. Of a total of 19 excised marks, approximately 79%, 63%, and 62% were visible on MRI, CT, and US, respectively. The average maximum temperature elevation in the marks during MRgFUS was 39.7 ± 10.1 °C, and average dose diameter (i.e., the diameter of the area that achieved a thermal dose greater than 240 cumulative equivalent minutes at 43 °C) of the mark at the focal plane was 7.3 ± 2.1 mm. On MRI the average normalized signal intensities were significantly higher in marks compared to normal muscle (p < 0.05). On CT, the marked regions were approximately 10 HU lower than normal muscle (p < 0.05). The results demonstrate that MRgFUS can be used to create internal marks that are visible on MRI, CT and US.

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Evaluation of the thermal sensitivity of porcine liver in CT‐guided cryoablation: an initial study

et al. 2020

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Purpose: To evaluate computed tomography (CT)-based thermometry in cryoablation, the thermal sensitivity of an ex-vivo porcine liver was determined in an initial study design. Methods: The CT-guided cryoablation was performed in three porcine liver samples over a period of 10 min. Fiber optic temperature probes were positioned parallel to the shaft of the cryoprobe in an axial slice orientation. During ablation, temperature measurements were performed simultaneously with CT imaging at 5 s intervals. On the CT images, the average CT number was calculated for a region of interest of 3 9 3 pixels just below the tip of each temperature probe. A linear regression analysis was performed using eleven data sets to determine the dependence of the CT number on the temperature. Results: With decreasing temperature, an increasing hypodense area around the tip of the cryoprobe was observed on the CT images and decreasing values of the CT number were determined. Starting at a temperature of À 40°C a linear relation between the CT number and the temperature was determined and a thermal sensitivity of 0.95 HU/°C (R 2 = 0.73) was obtained. The thermal sensitivity was used to calculate color-coded temperature maps. The calculated temperature distribution corresponds quantitatively to the increasing hypodense area. Conclusions: A noninvasive CT-based temperature determination during cryoablation in a normal ex vivo porcine liver is feasible. A thermal sensitivity of 0.95 HU/°C was determined by linear regression analysis. A color-coded map of the temperature distribution was presented.

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Assessment of thermal sensitivity of CT during heating of liver: anex vivostudy

Abstract: The assessment of the thermal sensitivity of CT in ex-vivo pig liver tissue showed a linear dependency on temperature ≤90 °C. This result may be beneficial for the application of isotherms or thermal maps in CT images of liver tissue.

Cited by 19 publications

References 30 publications

Experimental assessment on feasibility of computed tomography-based thermometry for radiofrequency ablation on tissue equivalent polyacrylamide phantom

Experimental assessment on feasibility of computed tomography-based thermometry for radiofrequency ablation on tissue equivalent polyacrylamide phantom

Quantitative evaluation of internal marks made using MRgFUS as seen on MRI, CT, US, and digital color images – A pilot study

Evaluation of the thermal sensitivity of porcine liver in CT‐guided cryoablation: an initial study

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