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A novel method for quantitative monitoring of transplanted islets of langerhans by positive contrast magnetic resonance imaging.

ABSTRACT: The Automatic Quantitative Ultrashort Echo Time imaging (AQUTE) protocol for serial MRI allows quantitative in vivo monitoring of iron labeled pancreatic islets of Langerhans transplanted into the liver, quantifying graft implantation and persistence in a rodent model. Rats (n = 14), transplanted with iron oxide loaded cells (0-4000 islet equivalents, IEQ), were imaged using a 3D radial ultrashort echo time difference technique (dUTE) on a Siemens MAGNETOM 3T clinical scanner up to 5 months postsurgery. In vivo 3D dUTE images gave positive contrast from labeled cells, suppressing liver signal and small vessels, allowing automatic quantification. Position of labeled islet clusters was consistent over time and quantification of hyperintense pixels correlated with the number of injected IEQs (R² = 0.898, p < 0.0001), and showed persistence over time (5 months posttransplantation). Automatic quantification was superior to standard imaging and manual counting methods, due to the uniform suppressed background and high contrast, resulting in significant timesavings, reproducibility and ease of quantification. Three-dimensional coverage of the whole liver in the absence of cardiac/respiratory artifact provided further improvement over conventional imaging. This imaging protocol reliably quantifies transplanted islet mass and has high translational potential to clinical studies of transplanted pancreatic islets.

SUBMITTER: Crowe LA

PROVIDER: S-EPMC3110629 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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A novel method for quantitative monitoring of transplanted islets of langerhans by positive contrast magnetic resonance imaging.

Crowe L A LA Ris F F Nielles-Vallespin S S Speier P P Masson S S Armanet M M Morel P P Toso C C Bosco D D Berney T T Vallee J-P JP

American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons 20110512 6

The Automatic Quantitative Ultrashort Echo Time imaging (AQUTE) protocol for serial MRI allows quantitative in vivo monitoring of iron labeled pancreatic islets of Langerhans transplanted into the liver, quantifying graft implantation and persistence in a rodent model. Rats (n = 14), transplanted with iron oxide loaded cells (0-4000 islet equivalents, IEQ), were imaged using a 3D radial ultrashort echo time difference technique (dUTE) on a Siemens MAGNETOM 3T clinical scanner up to 5 months post ...[more]

PMID: 21564535

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Project description:ObjectivesBicuspid aortic valve patients can develop thoracic aortic aneurysms and therefore require serial imaging to monitor aortic growth. This study investigates the reliability of contrast-enhanced magnetic resonance angiography (CEMRA) volumetry compared with 2-dimensional diameter measurements to identify thoracic aortic aneurysm growth.Materials and methodsA retrospective, institutional review board-approved, and Health Insurance Portability and Accountability Act-compliant study was conducted on 20 bicuspid aortic valve patients (45 ± 8.9 years, 20% women) who underwent serial CEMRA with a minimum imaging follow-up of 11 months. Magnetic resonance imaging was performed at 1.5 T with electrocardiogram-gated, time-resolved CEMRA. Independent observers measured the diameter at the sinuses of Valsalva (SOVs) and mid ascending aorta (MAA) as well as ascending aorta volume between the aortic valve annulus and innominate branch. Intraobserver/interobserver coefficient of variation (COV) and intraclass correlation coefficient (ICC) were computed to assess reliability. Growth rates were calculated and assessed by Student t test (P < 0.05, significant). The diameter of maximal growth (DMG), defined as the diameter at SOV or MAA with the faster growth rate, was recorded.ResultsThe mean time of follow-up was 2.6 ± 0.82 years. The intraobserver COV was 0.01 for SOV, 0.02 for MAA, and 0.02 for volume (interobserver COV: 0.02, 0.03, 0.04, respectively). The ICC was 0.83 for SOV, 0.86 for MAA, 0.90 for DMG, and 0.95 for volume. Average aortic measurements at baseline and (follow-up) were 42 ± 3 mm (42 ± 3 mm, P = 0.11) at SOV, 46 ± 4 mm (47 ± 4 mm, P < 0.05) at MAA, and 130 ± 23 mL (144 ± 24 mL, P < 0.05). Average size changes were 0.2 ± 0.6 mm/y (1% ± 2%) at SOV, 0.5 ± 0.8 mm/y (1% ± 2%) at MAA, 0.7 ± 0.7 mm/y (2% ± 2%) at DMG, and 6 ± 3 mL/y (4% ± 3%) with volumetry.ConclusionsThree-dimensional CEMRA volumetry exhibited a larger effect when examining percentage growth, a better ICC, and a marginally lower COV. Volumetry may be more sensitive to growth and possibly less affected by error than diameter measurements.

Dataset Information

A novel method for quantitative monitoring of transplanted islets of langerhans by positive contrast magnetic resonance imaging.

Publications

A novel method for quantitative monitoring of transplanted islets of langerhans by positive contrast magnetic resonance imaging.

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