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Phase-Contrast Hounsfield Units of Fixated and Non-Fixated Soft-Tissue Samples.

Willner M, Fior G, Marschner M, Birnbacher L, Schock J, Braun C, Fingerle AA, Noël PB, Rummeny EJ, Pfeiffer F, Herzen J - PLoS ONE (2015)

Bottom Line: Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples.A large variety of tissue specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector.Furthermore, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics & Institute of Medical Engineering, Technische Universität München, Garching, Germany.

ABSTRACT
X-ray phase-contrast imaging is a novel technology that achieves high soft-tissue contrast. Although its clinical impact is still under investigation, the technique may potentially improve clinical diagnostics. In conventional attenuation-based X-ray computed tomography, radiological diagnostics are quantified by Hounsfield units. Corresponding Hounsfield units for phase-contrast imaging have been recently introduced, enabling a setup-independent comparison and standardized interpretation of imaging results. Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples. This study presents phase-contrast Hounsfield units for various types of non-fixated human soft tissues. A large variety of tissue specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector. Furthermore, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results.

No MeSH data available.


Related in: MedlinePlus

Representative phase-contrast imaging results of non-fixated and fixated tissue samples.(a) Photograph of porcine fat and rind samples on which the effects of formalin fixation were investigated (note the presence of skin, muscle and adipose tissues). Samples were immersed in physiological saline or fixated with formaldehyde solutions of varying concentrations. (b) Phase-contrast axial slice through a non-fixated porcine sample. Skin, muscle and adipose tissues are clearly differentiated by their signal intensities. (c) Phase-contrast image of a sample fixated in typical preservation solution (containing 3.7% formaldehyde). (d) Phase-contrast image of a sample fixated in 18.5% formaldehyde solution. The signal intensities in b) are visually indistinguishable from those of (c).
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pone.0137016.g002: Representative phase-contrast imaging results of non-fixated and fixated tissue samples.(a) Photograph of porcine fat and rind samples on which the effects of formalin fixation were investigated (note the presence of skin, muscle and adipose tissues). Samples were immersed in physiological saline or fixated with formaldehyde solutions of varying concentrations. (b) Phase-contrast axial slice through a non-fixated porcine sample. Skin, muscle and adipose tissues are clearly differentiated by their signal intensities. (c) Phase-contrast image of a sample fixated in typical preservation solution (containing 3.7% formaldehyde). (d) Phase-contrast image of a sample fixated in 18.5% formaldehyde solution. The signal intensities in b) are visually indistinguishable from those of (c).

Mentions: Three series of measurements were performed in this study. First, we investigated the differences in the quantitative HUp values of fixated and non-fixated tissue samples. We then examined the relationship between the obtained HUp values and formalin concentration. Finally, we determined the HUp values of non-fixated human tissue types. For the first two series, porcine fat and rind was obtained from the local butcher and cut into cubic pieces (approximately 2 cm each side). Representative samples are photographed in Fig 2(A). All samples include the rind (representing skin or connective tissue), two layers of fat (adipose tissue) and two layers of muscle tissue. The non-fixated samples were immersed in physiological phosphate buffered saline solution (PBS) and measured within 24 h of acquisition and preparation. The fixated samples were placed in containers filled with different concentrations of formaldehyde gas in water (1.85%, 3.7%, 7.4%, 12.3% and 18.5%) and incubated for approximately 2 weeks before measurement. The first series of measurements included five non-fixated samples of porcine fat and rind (in PBS) and five samples preserved in 3.7% formaldehyde solution (typical formaldehyde concentration of tissue fixative). The results of these measurements were used to identify the variances of a tissue’s HUp value among different samples and to quantify the magnitude of formalin induced changes. The second series of measurements was performed to get a better idea of how or why the formalin fixation may influence a tissue’s HUp value. Four additional porcine fat and rind samples were examined within this series, each of them prepared with a different concentration of formaldehyde gas in water (1,85%, 7.4%, 12.3% and 18.5%). The human tissue samples investigated within the third series of measurements were excised at the Institute of Forensic Medicine (Ludwig Maximilian Universität München, Germany) and approved by the Ethics Committee of the Faculty of Medicine of the Technische Universität München. The review board waived the need for consent. Two small pieces of the following tissue types were obtained: heart muscle, skin, tendon, liver, spleen, kidney, pancreas and brain. The heart muscle, skin and kidney samples further contained adipose tissue. The tissues were retained in PBS and stored in the refrigerator at 4°C. Each tissue type was scanned no later than three days after excision.


Phase-Contrast Hounsfield Units of Fixated and Non-Fixated Soft-Tissue Samples.

Willner M, Fior G, Marschner M, Birnbacher L, Schock J, Braun C, Fingerle AA, Noël PB, Rummeny EJ, Pfeiffer F, Herzen J - PLoS ONE (2015)

Representative phase-contrast imaging results of non-fixated and fixated tissue samples.(a) Photograph of porcine fat and rind samples on which the effects of formalin fixation were investigated (note the presence of skin, muscle and adipose tissues). Samples were immersed in physiological saline or fixated with formaldehyde solutions of varying concentrations. (b) Phase-contrast axial slice through a non-fixated porcine sample. Skin, muscle and adipose tissues are clearly differentiated by their signal intensities. (c) Phase-contrast image of a sample fixated in typical preservation solution (containing 3.7% formaldehyde). (d) Phase-contrast image of a sample fixated in 18.5% formaldehyde solution. The signal intensities in b) are visually indistinguishable from those of (c).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556454&req=5

pone.0137016.g002: Representative phase-contrast imaging results of non-fixated and fixated tissue samples.(a) Photograph of porcine fat and rind samples on which the effects of formalin fixation were investigated (note the presence of skin, muscle and adipose tissues). Samples were immersed in physiological saline or fixated with formaldehyde solutions of varying concentrations. (b) Phase-contrast axial slice through a non-fixated porcine sample. Skin, muscle and adipose tissues are clearly differentiated by their signal intensities. (c) Phase-contrast image of a sample fixated in typical preservation solution (containing 3.7% formaldehyde). (d) Phase-contrast image of a sample fixated in 18.5% formaldehyde solution. The signal intensities in b) are visually indistinguishable from those of (c).
Mentions: Three series of measurements were performed in this study. First, we investigated the differences in the quantitative HUp values of fixated and non-fixated tissue samples. We then examined the relationship between the obtained HUp values and formalin concentration. Finally, we determined the HUp values of non-fixated human tissue types. For the first two series, porcine fat and rind was obtained from the local butcher and cut into cubic pieces (approximately 2 cm each side). Representative samples are photographed in Fig 2(A). All samples include the rind (representing skin or connective tissue), two layers of fat (adipose tissue) and two layers of muscle tissue. The non-fixated samples were immersed in physiological phosphate buffered saline solution (PBS) and measured within 24 h of acquisition and preparation. The fixated samples were placed in containers filled with different concentrations of formaldehyde gas in water (1.85%, 3.7%, 7.4%, 12.3% and 18.5%) and incubated for approximately 2 weeks before measurement. The first series of measurements included five non-fixated samples of porcine fat and rind (in PBS) and five samples preserved in 3.7% formaldehyde solution (typical formaldehyde concentration of tissue fixative). The results of these measurements were used to identify the variances of a tissue’s HUp value among different samples and to quantify the magnitude of formalin induced changes. The second series of measurements was performed to get a better idea of how or why the formalin fixation may influence a tissue’s HUp value. Four additional porcine fat and rind samples were examined within this series, each of them prepared with a different concentration of formaldehyde gas in water (1,85%, 7.4%, 12.3% and 18.5%). The human tissue samples investigated within the third series of measurements were excised at the Institute of Forensic Medicine (Ludwig Maximilian Universität München, Germany) and approved by the Ethics Committee of the Faculty of Medicine of the Technische Universität München. The review board waived the need for consent. Two small pieces of the following tissue types were obtained: heart muscle, skin, tendon, liver, spleen, kidney, pancreas and brain. The heart muscle, skin and kidney samples further contained adipose tissue. The tissues were retained in PBS and stored in the refrigerator at 4°C. Each tissue type was scanned no later than three days after excision.

Bottom Line: Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples.A large variety of tissue specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector.Furthermore, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics & Institute of Medical Engineering, Technische Universität München, Garching, Germany.

ABSTRACT
X-ray phase-contrast imaging is a novel technology that achieves high soft-tissue contrast. Although its clinical impact is still under investigation, the technique may potentially improve clinical diagnostics. In conventional attenuation-based X-ray computed tomography, radiological diagnostics are quantified by Hounsfield units. Corresponding Hounsfield units for phase-contrast imaging have been recently introduced, enabling a setup-independent comparison and standardized interpretation of imaging results. Thus far, the experimental values of few tissue types have been reported; these values have been determined from fixated tissue samples. This study presents phase-contrast Hounsfield units for various types of non-fixated human soft tissues. A large variety of tissue specimens ranging from adipose, muscle and connective tissues to liver, kidney and pancreas tissues were imaged by a grating interferometer with a rotating-anode X-ray tube and a photon-counting detector. Furthermore, we investigated the effects of formalin fixation on the quantitative phase-contrast imaging results.

No MeSH data available.


Related in: MedlinePlus