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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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High-resolution MRI reveals the structure of the entire mouse pancreas. A and B: Whole mouse pancreata (300-μm-thick slices) were imaged ex vivo, with 50 μm in plane resolution (TR/TE = 282/7 ms). A: In an image obtained without contrast agent, pancreatic lobules are seen, most of which feature a somewhat homogeneous and structureless content at this low magnification. Scale bar: 1 mm. B: Under these conditions, MRI infrequently identified putative islets of Langerhans (green arrows) within the intact pancreas. Scale bar: 1 mm. C: The contrast of pancreatic lobules was enhanced after intravenous infusion of MnCl2 combined with an intraperitoneal injection of glucose. Under these conditions, MRI allowed to distinguish whitish tubular structures, as well as highly contrasted round-ovoid structures of various sizes. The smallest of these structures (<0.5 mm; green arrows) was observed within the pancreatic lobules. Larger structures (>1 mm) were seen between the lobules. The latter structures were identified by histological analysis of the very same pancreas, confirming that MRI differentiates the pancreatic parenchyma from intrapancreatic lymphatic ganglia (C1), spleen (C2), and loops of small intestine (C3). Scale bar: 1 mm in A–C; 0.5 mm in lower panels B1–3. (A high-quality digital representation of this figure is available in the online issue.)
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Figure 1: High-resolution MRI reveals the structure of the entire mouse pancreas. A and B: Whole mouse pancreata (300-μm-thick slices) were imaged ex vivo, with 50 μm in plane resolution (TR/TE = 282/7 ms). A: In an image obtained without contrast agent, pancreatic lobules are seen, most of which feature a somewhat homogeneous and structureless content at this low magnification. Scale bar: 1 mm. B: Under these conditions, MRI infrequently identified putative islets of Langerhans (green arrows) within the intact pancreas. Scale bar: 1 mm. C: The contrast of pancreatic lobules was enhanced after intravenous infusion of MnCl2 combined with an intraperitoneal injection of glucose. Under these conditions, MRI allowed to distinguish whitish tubular structures, as well as highly contrasted round-ovoid structures of various sizes. The smallest of these structures (<0.5 mm; green arrows) was observed within the pancreatic lobules. Larger structures (>1 mm) were seen between the lobules. The latter structures were identified by histological analysis of the very same pancreas, confirming that MRI differentiates the pancreatic parenchyma from intrapancreatic lymphatic ganglia (C1), spleen (C2), and loops of small intestine (C3). Scale bar: 1 mm in A–C; 0.5 mm in lower panels B1–3. (A high-quality digital representation of this figure is available in the online issue.)

Mentions: MRI (14.1T) was used to image the entire mouse pancreas in slices of 300 μm thickness and with a 50 μm in plane resolution. In the absence of a contrast agent, the images showed the lobular structure of the gland (Fig. 1A and Supplementary Fig. 2) and, within these lobules, occasional round-ovoid whitish bodies that corresponded in shape, size, and distribution to putative individual islets (Fig. 1B and Supplementary Fig. 2). Other, much larger structures were located between the pancreatic lobules (Fig. 1C). After infusion of manganese and injection of a glucose dose known to stimulate β-cells, the contrast of the lobular and interlobular structures was enhanced (Fig. 1C and Supplementary Fig. 2).


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)

High-resolution MRI reveals the structure of the entire mouse pancreas. A and B: Whole mouse pancreata (300-μm-thick slices) were imaged ex vivo, with 50 μm in plane resolution (TR/TE = 282/7 ms). A: In an image obtained without contrast agent, pancreatic lobules are seen, most of which feature a somewhat homogeneous and structureless content at this low magnification. Scale bar: 1 mm. B: Under these conditions, MRI infrequently identified putative islets of Langerhans (green arrows) within the intact pancreas. Scale bar: 1 mm. C: The contrast of pancreatic lobules was enhanced after intravenous infusion of MnCl2 combined with an intraperitoneal injection of glucose. Under these conditions, MRI allowed to distinguish whitish tubular structures, as well as highly contrasted round-ovoid structures of various sizes. The smallest of these structures (<0.5 mm; green arrows) was observed within the pancreatic lobules. Larger structures (>1 mm) were seen between the lobules. The latter structures were identified by histological analysis of the very same pancreas, confirming that MRI differentiates the pancreatic parenchyma from intrapancreatic lymphatic ganglia (C1), spleen (C2), and loops of small intestine (C3). Scale bar: 1 mm in A–C; 0.5 mm in lower panels B1–3. (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 1: High-resolution MRI reveals the structure of the entire mouse pancreas. A and B: Whole mouse pancreata (300-μm-thick slices) were imaged ex vivo, with 50 μm in plane resolution (TR/TE = 282/7 ms). A: In an image obtained without contrast agent, pancreatic lobules are seen, most of which feature a somewhat homogeneous and structureless content at this low magnification. Scale bar: 1 mm. B: Under these conditions, MRI infrequently identified putative islets of Langerhans (green arrows) within the intact pancreas. Scale bar: 1 mm. C: The contrast of pancreatic lobules was enhanced after intravenous infusion of MnCl2 combined with an intraperitoneal injection of glucose. Under these conditions, MRI allowed to distinguish whitish tubular structures, as well as highly contrasted round-ovoid structures of various sizes. The smallest of these structures (<0.5 mm; green arrows) was observed within the pancreatic lobules. Larger structures (>1 mm) were seen between the lobules. The latter structures were identified by histological analysis of the very same pancreas, confirming that MRI differentiates the pancreatic parenchyma from intrapancreatic lymphatic ganglia (C1), spleen (C2), and loops of small intestine (C3). Scale bar: 1 mm in A–C; 0.5 mm in lower panels B1–3. (A high-quality digital representation of this figure is available in the online issue.)
Mentions: MRI (14.1T) was used to image the entire mouse pancreas in slices of 300 μm thickness and with a 50 μm in plane resolution. In the absence of a contrast agent, the images showed the lobular structure of the gland (Fig. 1A and Supplementary Fig. 2) and, within these lobules, occasional round-ovoid whitish bodies that corresponded in shape, size, and distribution to putative individual islets (Fig. 1B and Supplementary Fig. 2). Other, much larger structures were located between the pancreatic lobules (Fig. 1C). After infusion of manganese and injection of a glucose dose known to stimulate β-cells, the contrast of the lobular and interlobular structures was enhanced (Fig. 1C and Supplementary Fig. 2).

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