The Journal of Plastination

Published in J. Int. Soc. Plast. 14 (1): 18-21 (1999)

The E12 Technique as an Accessory Tool for the Study of Myocardial Fiber Structure Analysis in MRI

AUTHORS:
E. Skalkos1 , G. Williams1 , C.A.C. Baptista2
affiliations:

Department of Radiology1 and Pathology2, Medical College of Ohio, Toledo, Ohio, U.S.A.

ABSTRACT:

This paper documents use of the plastination E12 techique to analyze myocardial fiber arrangement and compare its pattern of distribution to magnetic resonance (MR) images. Human hearts were embed in a "plastic block" consisting of gelatin and polyethylene glycol and scanned using a General Electric Superconducting Magnet (Signa). After scanning the hearts were sectioned and processed for plastination. The E12 plastinated heart sections allowed visualization of the 3-dimensional details of the heart, vessels and myocardial bundles for comparison with the MR images. The myocardial fibers seen in the MR images showed similar gradient directions and details to the anatomical heart sections.

KEY WORDS:

Heart, Magnetic Resonance Imaging, E12 Technique, Myocardial Fibers

*CORRESPONDENCE TO:

C.A.C. Baptista, M.D. Ph.D., Medical College of Ohio, Department of Pathology, 3035 Arlington Avenue, Toledo, Ohio 43614-4804 U.S.A. Telephone: 419 383 6326 /Fax: 419 383 3066. Email: cbaptista@mco.edu

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Article Statistics

Volume: 14
Issue: 1
Allocation-id: 0000

Submitted Date:March 1, 1999
Accepted Date: May 3, 1999
Published Date: July 31, 1999

DOI Information:       https://doi.org/10.56507/ZLPM3596

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Article Citation

The Journal of Plastination (February 24, 2024) The E12 Technique as an Accessory Tool for the Study of Myocardial Fiber Structure Analysis in MRI. Retrieved from https://journal.plastination.org/articles/the-e12-technique-as-an-accessory-tool-for-the-study-of-myocardial-fiber-structure-analysis-in-mri/.
"The E12 Technique as an Accessory Tool for the Study of Myocardial Fiber Structure Analysis in MRI." The Journal of Plastination - February 24, 2024, https://journal.plastination.org/articles/the-e12-technique-as-an-accessory-tool-for-the-study-of-myocardial-fiber-structure-analysis-in-mri/
The Journal of Plastination - The E12 Technique as an Accessory Tool for the Study of Myocardial Fiber Structure Analysis in MRI. [Internet]. [Accessed February 24, 2024]. Available from: https://journal.plastination.org/articles/the-e12-technique-as-an-accessory-tool-for-the-study-of-myocardial-fiber-structure-analysis-in-mri/
"The E12 Technique as an Accessory Tool for the Study of Myocardial Fiber Structure Analysis in MRI." The Journal of Plastination [Online]. Available: https://journal.plastination.org/articles/the-e12-technique-as-an-accessory-tool-for-the-study-of-myocardial-fiber-structure-analysis-in-mri/. [Accessed: February 24, 2024]

INTRODUCTION

The timing and adequacy of reperfusion of an infarcted- related artery (Croisille et al., 1999) determine patient prognosis in acute myocardial infarction. To limit ischemic myocardial injury, it is important to differentiate viable from infarcted (non viable) myocardium. Assessment of viability is based on either stress echocardiography or trace techniques; however, those methods have limited spatial resolution. For a review on predicting myocardial viability by MRI see Higgins (1999).

Magnetic Resonance Imaging (MRI) has the ability to quantify myocardial 3D deformation and strain precisely and non-invasively. In order to document that the MR (magnetic resonance) permit a true comparison between the generated images and the anatomy of the scanned organ, hearts were scanned and then sectioned so that anatomical details of each slice could be compared to the details in the image. The use of plastinated specimens seemed ideal for this purpose. The acquired transparency of the specimens as final result of the E12 technique permitted a 3D analysis and true comparison to the images generated by the MRI. Plastinated specimens can be stored for long-term use, and do not give off fixative fumes. Plastination is also a relatively simple and easier method to obtain clear specimens when compared to traditional methods such as Spaltholz (1924) and Tompsett (1956).

Since the birth of plastination in the mid-80s, sever authors have successfully used plastinated specimens to correlate morphology with MRI in research, education and clinical medicine (McNiesh and von Hagens, 1988; Baptista et al., 1990; Ripani et al., 1993, 1996; Hussain et al. ,1996; Magiros et al. ,1996,1997; Cook, 1997; Entius et al., 1997).

This paper introduces the E-12 technique as a tool for the comparative analysis of myocardial fiber distribution study using MRI.

MATERIALS AND METHODS

Materials

Several human hearts were used for this study. The hearts were removed from cadavers and washed in tap water to remove blood and blood clots from the chambers, coronary arteries and cardiac veins. After the blood was removed, the heart chambers were filled in with cotton to maintain the cavities in the dilated state.

The coronary arteries were injected with a mixture of 30% gelatin and 0.1ml (0.05mmol)/kg of gadopentetate dimeglumine (Magnevist® - Berlex Laboratories, Inc., Wayne, NJ 07470, USA). Eosin (Sigma-Aldrich, 3050 Spruce Street, St Louis, MO 53178, USA) was added to the mixture for color.

The hearts were then immersed in a 10% formalin solution for 24 hours. After fixation the hearts were prepared for MRI scanning.

Preparation of the heart for scanning

The hearts were immersed in a solution of gelatin (15 gm/100ml) and polyethylene glycol 1000 (lOml/lOOml of gelatin solution) using the method described by McCormick (1961). This plastic/gelatin solution was transparent and after solidifying maintained the position of the heart during the MRI scan and during physical sectioning.

Scanning 

MRI images were obtained using the General Electric Superconducting Magnet (Signa) operating at 1.5 Tesla with a corresponding resonance frequency for protons of 63.9 MHz.

The scan protocol is a balanced matrix spin echo gated acquisition, (TR=2000 msec, TE=20 and 60 msec) for oblique, sagittal and/or coronal short and long axis views of the myocardium. Two images were generated at each anatomic level: one was formed from the first spin-echo (TE=20 msec) and the other from the second echo (TE=60 msec). The MR scan slice thickness was 3.0 mm with a skip distance of 3.0 mm. The images were archived to magnetic tape and transferred to the imaging workstation for analysis. Medical College of Ohio (MCO) software on the DEC microVax workstation allowed display, image processing and texture analysis of the images.

Image processing and mathematical codes have been written on the DEC microVax Workstation to analyze texture on the intensity distributions of the tissues scanned in the MR scanner.The cardiac slices were preserved by plastinau'on for future study and permanent storage.

Sectioning

The "plastic block" (gelatin and polyethylene glycol) was sectioned using an electric circular meat slicer. Three millimeters (3 mm) sections were made parallel to the long axis of the left ventricle. Each slice was placed between plastic grids and immersed in cold acetone (-25°C) for dehydration.

Dehydration

Freeze substitution as described by von Hagens (1985) and von Hagens et al. (1987) was used for dehydration. Three changes of acetone were necessary, with each bath containing a volume of acetone 5-10 times the volume of the specimens.

After dehydration, the heart sections were immersed in methylene chloride for defatting. Two weekly changes of methylene chloride were necessary. After defatting the sections were impregnated with epoxy.

Impregnation

Impregnation using an epoxy based reaction mixture (El2) technique was performed at room temperature. The epoxy reaction mixture was: E12/AT30/AT10/E1 (95:5:20:26 pbw).

The specimens were submerged in the reaction mixture and placed in a vacuum chamber, directly from the methylene chloride solution. Pressure was reduced rapidly to lOmmHg. The rapid boiling out of the methylene chloride caused the temperature of the mixture to be reduced drastically. This helped to control the exothermic reaction taking place (Weber and Henry, 1993). Impregnation was accomplished in 24 hours.

Casting

The heart sections were cast between two sheets of tempered glass and a flexible gasket (Parker O-Ring - Zatkoff Seals & Packing, 8929 Airport HWY. Holland, Ohio 43528- 9604, USA) was used as spacer. The following mixture was used as the casting resin: E12/AT30/E1 (95:5:26 pbw).

The specimens were placed between two glass plates, sealed and the molds filled with the casting mixture. After the molds were filled in they were placed inside a vacuum chamber to remove small bubbles present in the resin. This took place in 45 minutes to 1 hour. Larger bubbles were afterwards removed manually. After bubble removal, the mold was placed at horizontal 15° incline to assure correct positioning of the heart slice in the mold. When the polymer showed more viscosity and was tacky (2 to 3 days) the specimens were placed in an oven at 40°C for 10 days. Hardening was completed when "Newton" rings were seen in the casting molds. The glass plates were removed carefully and the sheets were cut and trimmed as desired.

Cutting and sanding the molds

A bend saw (Sears Roebuck and Co., 3333 Beverly Road, Hoffman Estate, IL 60179, USA) was used to cut and trim the plastic along the edges of the heart slices. Belt and disc sanders from Sears Roebuck and Co. were used to remove sharp edges from the plastic slices.

Photographic images of the 3.0 mm anatomical sections and MR scan slices were compared.

RESULTS

In order to evaluate the quality of cardiac imaging of the GE MR scanner at the Medical College of Ohio, and to verify anatomical details on the MR images, several cadaver hearts were imaged and sectioned at 3 mm intervals. The heart images were processed using zoom, filters contour and cut modules. The maximum gradient images were then obtained and filtered. The gradient images were subtracted from the original images of the myocardium using an absolute subtraction method, to enhance the direction and structure of the muscle bundles in the myocardium. The heart sections processed by the E12 technique were correlated with the MR images showing that the myocardium can be identified in the computer-processed images. Maximum gradient processing emphasizes the direction of the muscle bundles and such images show similar gradient directions and details seen with the anatomical heart sections. Examples of the resulting anatomical slices and an intermediate scanned image are shown in figure 1.

Figure 1: Photographs of plastinated heart sections (A, B) and an intermediate magnetic resonance image (C) showing the following structures: left atrium (LA); right atrium (RA); left ventricle (V) and myocardial bundles an fibers (arrows).

DISCUSSION

Magnevist® (that was injected in the coronary arteries mixed with gelatin and red dye) is a paramagnetic metal ion chelate used in clinical diagnostic procedures as an injectable enhancement agent to enhance signal intensity, and thus visual contrast, in magnetic resonance imaging.

McCormick's method (1961) to obtain cross sections of fresh tissue was helpful to align and section the heart similar to the coordinates used for MR scanning. Positioning the heart in the mixture of gelatin and polyethylene glycol 1000 ensured stability during the scan as well as during sectioning. Marking the MR scan lines on the container facilitated sawing the specimen in the same planes as the scans. The resultant images were closely related to the scan sections.

Parker O-Ring from Zatkoff was an ideal locally available product to use for the gasket in the plastination mold. It is of a flexible base polymer, nitrile and is supplied in a variety of diameters (3 mm to 10 mm). In our case the thickness used was 3 mm.

The El2 sheet specimens allowed visualization of the 3-dimensional detail of the heart, vessels and myocardial bundles for comparison with the MR images. Maximum gradient processing emphasizes the direction of the muscle bundles and such images show similar gradient directions and details with the anatomical heart sections.

Acknowledgement

 The authors wish to thank Dr. Robert W. Henry, College of Veterinary Medicine, The University of Tennessee, for his critical review of this manuscript, and Tina Kinkaid and Carol Okenka, Department of Radiology, Medical College of Ohio for their assistance with the MRI scanning.

REFERENCES

Baptista CAC, Henry RW, Williams G, Brinker R: Magnetic resonance imaging of plastinated specimens: study of tissue characteristics and evaluation of the hardening process of the S10 technique. presented at The 5th International Conference on Plastination, Faculty of Medicine, University of Heidelberg, Germany July 1990 J Int Soc Plastination 4:3, 1990.

Cook P: Sheet plastination as a clinically based teaching aid at the University of Auckland. Acta Anat 158(1): 33- 36, 1997.
https://doi.org/10.1159/000147907

Croisille P, Moore CC, Judd RM, Lima JAC, Arai M, Me Veigh ER, Becker LC, Zerhouni EA: Differentiation of viable and nonviable myocardium by the use of three- dimensional tagged MRI in 2-day-old reperfused canine infarcts. Circulation 99: 284-291,1999.
https://doi.org/10.1161/01.CIR.99.2.284

Entius CAC, van Rijn RR, Holstege JC, Stoeckart R, Zwamborn AW: Correlating sheet plastination slices, computed tomography images and magnetic resonance images of the pelvic girdle: a teaching tool. Acta Anat 158(1): 44-47,1997.
https://doi.org/10.1159/000147909

Higgins CB: Prediction of myocardial viability by MRI. Circulation 99: 727-729, 1999.
https://doi.org/10.1161/01.CIR.99.6.727

Hussain SM, Stoker J, Entius CAC, van Rijn RR, Zwamborn AW, den Hollander JC, Lameris JS: Endoanal magnetic resonance imaging of the anal sphincter complex: correlation with sheet plastination slices and histology. Presented at The 8th International Conference on Plastination - University of Queensland, Brisbane, Australia. July 1996. J Int Soc Plastination 11(1): 5, 1996.

Magiros M, Kekic M, Mills FR, Cheyne-Macpherson S, Huand M, Doran GA: Magnetic resonance imaging (MRI) versus thin plastinated cadaveric sections as an anatomic learning tool.Presented at The 8th International Conference on Plastination - University of Queensland, Brisbane, Australia. July 1996. J Int Soc Plastination 11(1): 12, 1996.

Magiros M, Kekic M, Doran GA: Learning relational anatomy by correlating thin plastinated sections and magnetic resonance images: preparation of specimens Acta Anat 158(1): 37-43, 1997.
https://doi.org/10.1159/000147908

McCormick JE: Serial Sections of Gross Anatomy. Arch Path 72 (6): 93-95,1961.

McNiesh LM, von Hagens G: The diagnostic imaging characteristics of plastinated anatomical specimens. J Int Soc Plastination 2(1): 24-39, 1988.
https://doi.org/10.56507/RMEK8272

Ripani M, Bassi A, Perracchio L, Boccoa ML, Tomaselli G, Giacomelli L, Messinett S, Marinozzi G: Comparative analysis of a plastination specimens and clinical diagnostic images. J Int Soc Plastination 8(1): 12-13, 1993.
https://doi.org/10.56507/LTRN2626

Ripani M, Di Cosimo E, Franco T, Crecco M: Comparative study of NMR-CAT images within series plastinated sections. J Int Soc Plastination 11(1): 22-23, 1996.
https://doi.org/10.56507/XSHS9551

Spaltholz W: Das Durchsichtigmachen als biologische Arbeitsmethode. Handb. Biol. Arbeitsmethoden, Abt. 9 Berlin. Wien, 1924.

Tompsett DH: Anatomical Techniques. Edinburgh, London: E & S Livingstone, 1956.

von Hagens G: Heidelberg Plastination Folder: Collection of all technical leaflets for plastination. Anatomische Institut 1, Universitat Heidelberg, Heidelberg, Germany, 1985.

von Hagens G, Tiedmann K, Kriz W: The current potential of plastination. Anat Embryol 175: 411-421, 1987.
https://doi.org/10.1007/BF00309677

Weber W, Henry RW: Sheet plastination of body slices - E 12 technique, filling method. J Int Soc Plastination 7:16-22,1993
https://doi.org/10.56507/EZGX2343

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