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High-resolution magnetic resonance imaging quantitatively detects individual pancreatic islets.

Lamprianou S, Immonen R, Nabuurs C, Gjinovci A, Vinet L, Montet XC, Gruetter R, Meda P - Diabetes (2011)

Bottom Line: In all cases, MR images were acquired in a 14.1 Tesla scanner and correlated with the corresponding (immuno)histological sections.MEHFMRI also detected a significant decrease in the numerical and volume density of islets in STZ-injected mice.However, in the latter measurements the loss of β-cells was undervalued under the conditions tested.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland. smaragda.lamprianou@unige.ch

ABSTRACT

Objective: We studied whether manganese-enhanced high-field magnetic resonance (MR) imaging (MEHFMRI) could quantitatively detect individual islets in situ and in vivo and evaluate changes in a model of experimental diabetes.

Research design and methods: Whole pancreata from untreated (n = 3), MnCl(2) and glucose-injected mice (n = 6), and mice injected with either streptozotocin (STZ; n = 4) or citrate buffer (n = 4) were imaged ex vivo for unambiguous evaluation of islets. Exteriorized pancreata of MnCl(2) and glucose-injected mice (n = 6) were imaged in vivo to directly visualize the gland and minimize movements. In all cases, MR images were acquired in a 14.1 Tesla scanner and correlated with the corresponding (immuno)histological sections.

Results: In ex vivo experiments, MEHFMRI distinguished different pancreatic tissues and evaluated the relative abundance of islets in the pancreata of normoglycemic mice. MEHFMRI also detected a significant decrease in the numerical and volume density of islets in STZ-injected mice. However, in the latter measurements the loss of β-cells was undervalued under the conditions tested. The experiments on the externalized pancreata confirmed that MEHFMRI could visualize native individual islets in living, anesthetized mice.

Conclusions: Data show that MEHFMRI quantitatively visualizes individual islets in the intact mouse pancreas, both ex vivo and in vivo.

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Related in: MedlinePlus

Individual pancreatic islets are visualized by MRI. A: This MR image (left) is a high magnification view of the pancreas shown in Fig. 1C, recorded with a 50 μm in plane resolution. Small, round-ovoid whitish structures (several are pointed by green arrows) are seen dispersed within the pancreatic lobules. Histology (right) confirmed that these structures are pancreatic islets of Langerhans, dispersed within the exocrine parenchyma, between vessels and ducts (white arrows). Scale bar: 1 mm. B: Quantification of the islet signal intensity, relative to that of the surrounding exocrine tissue, confirmed that the MR image of islets was more contrasted (***P < 0.001) in the Mn2+-infused mice (red bar) than in noninfused controls (blue bar). Values are means + SEM of the number of islets indicated within the columns. a.u., Arbitrary units. (A high-quality digital representation of this figure is available in the online issue.)
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Figure 2: Individual pancreatic islets are visualized by MRI. A: This MR image (left) is a high magnification view of the pancreas shown in Fig. 1C, recorded with a 50 μm in plane resolution. Small, round-ovoid whitish structures (several are pointed by green arrows) are seen dispersed within the pancreatic lobules. Histology (right) confirmed that these structures are pancreatic islets of Langerhans, dispersed within the exocrine parenchyma, between vessels and ducts (white arrows). Scale bar: 1 mm. B: Quantification of the islet signal intensity, relative to that of the surrounding exocrine tissue, confirmed that the MR image of islets was more contrasted (***P < 0.001) in the Mn2+-infused mice (red bar) than in noninfused controls (blue bar). Values are means + SEM of the number of islets indicated within the columns. a.u., Arbitrary units. (A high-quality digital representation of this figure is available in the online issue.)

Mentions: To positively identify the pancreas structures seen by MRI, we processed each pancreas for histology and screened the sections that were the closest to the plane of the MRI image recorded within the 300-μm-thick tomographic slice of the samples (Figs. 1C and 2A). The presence in both images of ducts and vessels, as well as nonpancreatic tissues, helped precisely match the MRI and the histological images. This procedure confirmed the different appearance of the pancreas and close-by organs (such as spleen or intestines) and differentiated, within the gland, the lymphatic ganglia from the adjacent exocrine tissue (Fig. 1C). Moreover, higher magnification views of both MR images and corresponding histological sections confirmed that the small, round-ovoid structures scattered within the exocrine pancreas were bona fide pancreatic islets of Langerhans (Fig. 2A). In the MRI images of pancreata from mice that had not been infused with manganese, islets were also occasionally visible as hyperintense whitish bodies (Fig. 1B). However, the intensity of the islet signal, relative to that of the adjacent exocrine pancreas, was somewhat higher (P < 0.001, n = 27) after manganese infusion than in the noninfused controls (Fig. 2B).


High-resolution magnetic resonance imaging quantitatively detects individual pancreatic islets.

Lamprianou S, Immonen R, Nabuurs C, Gjinovci A, Vinet L, Montet XC, Gruetter R, Meda P - Diabetes (2011)

Individual pancreatic islets are visualized by MRI. A: This MR image (left) is a high magnification view of the pancreas shown in Fig. 1C, recorded with a 50 μm in plane resolution. Small, round-ovoid whitish structures (several are pointed by green arrows) are seen dispersed within the pancreatic lobules. Histology (right) confirmed that these structures are pancreatic islets of Langerhans, dispersed within the exocrine parenchyma, between vessels and ducts (white arrows). Scale bar: 1 mm. B: Quantification of the islet signal intensity, relative to that of the surrounding exocrine tissue, confirmed that the MR image of islets was more contrasted (***P < 0.001) in the Mn2+-infused mice (red bar) than in noninfused controls (blue bar). Values are means + SEM of the number of islets indicated within the columns. a.u., Arbitrary units. (A high-quality digital representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198086&req=5

Figure 2: Individual pancreatic islets are visualized by MRI. A: This MR image (left) is a high magnification view of the pancreas shown in Fig. 1C, recorded with a 50 μm in plane resolution. Small, round-ovoid whitish structures (several are pointed by green arrows) are seen dispersed within the pancreatic lobules. Histology (right) confirmed that these structures are pancreatic islets of Langerhans, dispersed within the exocrine parenchyma, between vessels and ducts (white arrows). Scale bar: 1 mm. B: Quantification of the islet signal intensity, relative to that of the surrounding exocrine tissue, confirmed that the MR image of islets was more contrasted (***P < 0.001) in the Mn2+-infused mice (red bar) than in noninfused controls (blue bar). Values are means + SEM of the number of islets indicated within the columns. a.u., Arbitrary units. (A high-quality digital representation of this figure is available in the online issue.)
Mentions: To positively identify the pancreas structures seen by MRI, we processed each pancreas for histology and screened the sections that were the closest to the plane of the MRI image recorded within the 300-μm-thick tomographic slice of the samples (Figs. 1C and 2A). The presence in both images of ducts and vessels, as well as nonpancreatic tissues, helped precisely match the MRI and the histological images. This procedure confirmed the different appearance of the pancreas and close-by organs (such as spleen or intestines) and differentiated, within the gland, the lymphatic ganglia from the adjacent exocrine tissue (Fig. 1C). Moreover, higher magnification views of both MR images and corresponding histological sections confirmed that the small, round-ovoid structures scattered within the exocrine pancreas were bona fide pancreatic islets of Langerhans (Fig. 2A). In the MRI images of pancreata from mice that had not been infused with manganese, islets were also occasionally visible as hyperintense whitish bodies (Fig. 1B). However, the intensity of the islet signal, relative to that of the adjacent exocrine pancreas, was somewhat higher (P < 0.001, n = 27) after manganese infusion than in the noninfused controls (Fig. 2B).

Bottom Line: In all cases, MR images were acquired in a 14.1 Tesla scanner and correlated with the corresponding (immuno)histological sections.MEHFMRI also detected a significant decrease in the numerical and volume density of islets in STZ-injected mice.However, in the latter measurements the loss of β-cells was undervalued under the conditions tested.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland. smaragda.lamprianou@unige.ch

ABSTRACT

Objective: We studied whether manganese-enhanced high-field magnetic resonance (MR) imaging (MEHFMRI) could quantitatively detect individual islets in situ and in vivo and evaluate changes in a model of experimental diabetes.

Research design and methods: Whole pancreata from untreated (n = 3), MnCl(2) and glucose-injected mice (n = 6), and mice injected with either streptozotocin (STZ; n = 4) or citrate buffer (n = 4) were imaged ex vivo for unambiguous evaluation of islets. Exteriorized pancreata of MnCl(2) and glucose-injected mice (n = 6) were imaged in vivo to directly visualize the gland and minimize movements. In all cases, MR images were acquired in a 14.1 Tesla scanner and correlated with the corresponding (immuno)histological sections.

Results: In ex vivo experiments, MEHFMRI distinguished different pancreatic tissues and evaluated the relative abundance of islets in the pancreata of normoglycemic mice. MEHFMRI also detected a significant decrease in the numerical and volume density of islets in STZ-injected mice. However, in the latter measurements the loss of β-cells was undervalued under the conditions tested. The experiments on the externalized pancreata confirmed that MEHFMRI could visualize native individual islets in living, anesthetized mice.

Conclusions: Data show that MEHFMRI quantitatively visualizes individual islets in the intact mouse pancreas, both ex vivo and in vivo.

Show MeSH
Related in: MedlinePlus