Limits...
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.

Show MeSH

Related in: MedlinePlus

MRI quantifies islet mass and size. A: Islets of different sizes were detected in the MR images of whole mouse pancreas (top) and confirmed by correlative histology (bottom). The right panels are enlargements of the regions boxed in the left panels. Scale bar: 1 mm. B: Islet sizes were measured in both MR and histology images. The distribution of the values was asymmetrical in both cases, confirming that islets <150 μm in diameter predominate in the control mouse pancreas, whereas islets >300 μm are rare. Of note, islets <50 μm in diameter escaped MRI detection. C: Further morphometric evaluation of MR images showed that MRI detected on the average 1 islet/mm3 of pancreas (left), accounting for a relative volume of the endocrine micro organs of 0.8 ± 0.2% (middle). A mean of 268 islets per animal (n = 5) was detected; Vvi, volume density of islets; Nvi, volume density of the islets (Ni/mm3 of pancreas); Vp, total volume of pancreas analyzed (mm3). Values are means + SEM of five control mice. (A high-quality digital representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3198086&req=5

Figure 3: MRI quantifies islet mass and size. A: Islets of different sizes were detected in the MR images of whole mouse pancreas (top) and confirmed by correlative histology (bottom). The right panels are enlargements of the regions boxed in the left panels. Scale bar: 1 mm. B: Islet sizes were measured in both MR and histology images. The distribution of the values was asymmetrical in both cases, confirming that islets <150 μm in diameter predominate in the control mouse pancreas, whereas islets >300 μm are rare. Of note, islets <50 μm in diameter escaped MRI detection. C: Further morphometric evaluation of MR images showed that MRI detected on the average 1 islet/mm3 of pancreas (left), accounting for a relative volume of the endocrine micro organs of 0.8 ± 0.2% (middle). A mean of 268 islets per animal (n = 5) was detected; Vvi, volume density of islets; Nvi, volume density of the islets (Ni/mm3 of pancreas); Vp, total volume of pancreas analyzed (mm3). Values are means + SEM of five control mice. (A high-quality digital representation of this figure is available in the online issue.)

Mentions: To compare the size of putative islets as well as their numerical and volume densities within the pancreas, the entire pancreata of five animals that had received both manganese and glucose were evaluated first by MRI and then by histology (Fig. 3A). Morphometry showed the expected asymmetrical distribution of islet sizes in histological sections (Fig. 3B). The size distribution determined by the MRI was significantly (P < 0.001) shifted to higher diameters, likely a result of partial volume effects of the 300 μm slice thickness, which made the detection of islets <50 μm in diameter difficult (Fig. 3B). Despite this limitation, MRI evaluated that the volume density of islets, i.e., the relative volume of islets within the pancreas, was on the average 0.8 ± 0.2% (n = 5; Fig. 3C). The average numerical density of islets was 1.2 ± 0.3 per mm3 of pancreas (n = 5).


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)

MRI quantifies islet mass and size. A: Islets of different sizes were detected in the MR images of whole mouse pancreas (top) and confirmed by correlative histology (bottom). The right panels are enlargements of the regions boxed in the left panels. Scale bar: 1 mm. B: Islet sizes were measured in both MR and histology images. The distribution of the values was asymmetrical in both cases, confirming that islets <150 μm in diameter predominate in the control mouse pancreas, whereas islets >300 μm are rare. Of note, islets <50 μm in diameter escaped MRI detection. C: Further morphometric evaluation of MR images showed that MRI detected on the average 1 islet/mm3 of pancreas (left), accounting for a relative volume of the endocrine micro organs of 0.8 ± 0.2% (middle). A mean of 268 islets per animal (n = 5) was detected; Vvi, volume density of islets; Nvi, volume density of the islets (Ni/mm3 of pancreas); Vp, total volume of pancreas analyzed (mm3). Values are means + SEM of five control mice. (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 3: MRI quantifies islet mass and size. A: Islets of different sizes were detected in the MR images of whole mouse pancreas (top) and confirmed by correlative histology (bottom). The right panels are enlargements of the regions boxed in the left panels. Scale bar: 1 mm. B: Islet sizes were measured in both MR and histology images. The distribution of the values was asymmetrical in both cases, confirming that islets <150 μm in diameter predominate in the control mouse pancreas, whereas islets >300 μm are rare. Of note, islets <50 μm in diameter escaped MRI detection. C: Further morphometric evaluation of MR images showed that MRI detected on the average 1 islet/mm3 of pancreas (left), accounting for a relative volume of the endocrine micro organs of 0.8 ± 0.2% (middle). A mean of 268 islets per animal (n = 5) was detected; Vvi, volume density of islets; Nvi, volume density of the islets (Ni/mm3 of pancreas); Vp, total volume of pancreas analyzed (mm3). Values are means + SEM of five control mice. (A high-quality digital representation of this figure is available in the online issue.)
Mentions: To compare the size of putative islets as well as their numerical and volume densities within the pancreas, the entire pancreata of five animals that had received both manganese and glucose were evaluated first by MRI and then by histology (Fig. 3A). Morphometry showed the expected asymmetrical distribution of islet sizes in histological sections (Fig. 3B). The size distribution determined by the MRI was significantly (P < 0.001) shifted to higher diameters, likely a result of partial volume effects of the 300 μm slice thickness, which made the detection of islets <50 μm in diameter difficult (Fig. 3B). Despite this limitation, MRI evaluated that the volume density of islets, i.e., the relative volume of islets within the pancreas, was on the average 0.8 ± 0.2% (n = 5; Fig. 3C). The average numerical density of islets was 1.2 ± 0.3 per mm3 of pancreas (n = 5).

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