Insulinoma MRI: Difference between revisions
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==Overview== | ==Overview== | ||
MRI has better sensitivity than CT scan. It is still considered as the second line of investigation due to cost and availability. Insulinoma shows low intensity on T1 weighted and high intensity on T2 weighted signals, having better visualization on T1 and T2 weighted images with fat suppression.They exhibit typically homogenous enhancement when small and ring enhancement when more than 2 cm. A similar pattern is seen in metastatic lesion as of primary tumor. | |||
==MRI== | ==MRI== | ||
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*T1 and T2 relaxation times for islet cell tumor like insulinoma has lower protein and proton concentration time | *T1 and T2 relaxation times for islet cell tumor like insulinoma has lower protein and proton concentration time | ||
* | *Abdominal MRI may be helpful in the diagnosis of insulinoma. Findings on MRI suggestive of Insulinoma include<ref name="pmid15763695">{{cite journal| author=Noone TC, Hosey J, Firat Z, Semelka RC| title=Imaging and localization of islet-cell tumors of the pancreas on CT and MRI. | journal=Best Pract Res Clin Endocrinol Metab | year= 2005 | volume= 19 | issue= 2 | pages= 195-211 | pmid=15763695 | doi=10.1016/j.beem.2004.11.013 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15763695 }} </ref>: | ||
**Low in signal intensity on fat suppressed T1-weighted images | **Low in signal intensity on fat suppressed T1-weighted images | ||
**High on intensity on fat suppressed T2-weighted images independent of lesion size | **High on intensity on fat suppressed T2-weighted images independent of lesion size | ||
**Enhancement patterns are due to hypervascularity | **Enhancement patterns are due to hypervascularity. Homogenous enhancement is exhibited commonly in insulinoma, ring enhancement if they are larger than 2 cm. | ||
**same pattern can be seen in metastatic lymph node as of the primary; homogenous when small and ring enhancement if tumor is more than 2 cm. | |||
*Modern MRI has rapid tri-phasic, breath held T1 rapid gadolinium- enhanced sequences which help to reduce artefacts produced by motion . | |||
*MRI enables accurate location of tumor in terms of resectability and involvement of vessels. | |||
**same pattern can be seen in metastatic lymph node as of the primary. | |||
==References== | ==References== | ||
Revision as of 20:56, 23 August 2017
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Insulinoma MRI On the Web |
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American Roentgen Ray Society Images of Insulinoma MRI |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Amandeep Singh M.D.[2]
Overview
MRI has better sensitivity than CT scan. It is still considered as the second line of investigation due to cost and availability. Insulinoma shows low intensity on T1 weighted and high intensity on T2 weighted signals, having better visualization on T1 and T2 weighted images with fat suppression.They exhibit typically homogenous enhancement when small and ring enhancement when more than 2 cm. A similar pattern is seen in metastatic lesion as of primary tumor.
MRI
MRI is superior in detecting insulinoma in that it has greater sensitivity currently ~85%. In a study of 21 insulinomas by Owen et al,the sensitivity was noted to be 94%.(19/21 cases). The 2 cases were of 5 and 7 mm size and in pancreatic tail[1][2]
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Insulinoma T1 fat sat- Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 10407 -
Insulinoma (Axial T1 C+fat sat)Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 10407 -
Insulinoma (Axial T2 fat sat)Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 10407 -
Insulinoma(T1C+ PV)Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 10407 -
Insulinoma- Case courtesy of Dr J. Ray Ballinger, Radiopaedia.org, rID: 23627 -
Insulinoma-Case courtesy of Dr Alejandro Cruz, Radiopaedia.org, rID: 30096
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- T1 and T2 relaxation times for islet cell tumor like insulinoma has lower protein and proton concentration time
- Abdominal MRI may be helpful in the diagnosis of insulinoma. Findings on MRI suggestive of Insulinoma include[3]:
- Low in signal intensity on fat suppressed T1-weighted images
- High on intensity on fat suppressed T2-weighted images independent of lesion size
- Enhancement patterns are due to hypervascularity. Homogenous enhancement is exhibited commonly in insulinoma, ring enhancement if they are larger than 2 cm.
- same pattern can be seen in metastatic lymph node as of the primary; homogenous when small and ring enhancement if tumor is more than 2 cm.
- Modern MRI has rapid tri-phasic, breath held T1 rapid gadolinium- enhanced sequences which help to reduce artefacts produced by motion .
- MRI enables accurate location of tumor in terms of resectability and involvement of vessels.
References
- ↑ Owen NJ, Sohaib SA, Peppercorn PD, Monson JP, Grossman AB, Besser GM; et al. (2001). "MRI of pancreatic neuroendocrine tumours". Br J Radiol. 74 (886): 968–73. doi:10.1259/bjr.74.886.740968. PMID 11675319.
- ↑ Thoeni RF, Mueller-Lisse UG, Chan R, Do NK, Shyn PB (2000). "Detection of small, functional islet cell tumors in the pancreas: selection of MR imaging sequences for optimal sensitivity". Radiology. 214 (2): 483–90. doi:10.1148/radiology.214.2.r00fe32483. PMID 10671597.
- ↑ Noone TC, Hosey J, Firat Z, Semelka RC (2005). "Imaging and localization of islet-cell tumors of the pancreas on CT and MRI". Best Pract Res Clin Endocrinol Metab. 19 (2): 195–211. doi:10.1016/j.beem.2004.11.013. PMID 15763695.