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Year : 2000  |  Volume : 10  |  Issue : 1  |  Page : 37-38
Spiral CT and MR appearances of pancreatic head insulinoma

Diwan Chand Satya Pal Affarwal Imaging Research Centre, India

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Keywords: Pancreas, CT, Insulinoma

How to cite this article:
Aggarwal B, Gothi R, Aggarwal A, Doda S S, Verma K. Spiral CT and MR appearances of pancreatic head insulinoma. Indian J Radiol Imaging 2000;10:37-8

How to cite this URL:
Aggarwal B, Gothi R, Aggarwal A, Doda S S, Verma K. Spiral CT and MR appearances of pancreatic head insulinoma. Indian J Radiol Imaging [serial online] 2000 [cited 2021 Feb 28];10:37-8. Available from:
Insulinomas are the commonest islet cell tumors of the pancreas. Due to their hypervascular nature, these tumors have characteristic imaging appearances. We present a case showing classical appearances on helical CT and MR. We would like to emphasize the need for performing helical CT whenever the diagnosis is suspected, due to the ability to image the pancreas in the early arterial as well as in the equilibrium phase. It should also be noted that water should be given instead of radio-opaque oral contrast, as islet cell tumors may also be found in the bowel wall.

   Case Report Top

A 37-years old man presented with a one-month history of fainting attacks and dizziness. On routine blood examination, all parameters were within limits, except for a reduced blood glucose level. A blood sample during one of the episodic attacks showed the blood glucose level to be 38 mg/dl.

A CT scan of the upper abdomen was requested. Helical CT of the upper abdomen was performed (AR.*, Siemens, Erlangen, German). Water was used as an oral contrast medium, to detect any tumor in the walls of the upper gastro-intestinal tract, which can be missed if radio-opaque contrast is used orally.

A solitary 1.3 x 1.4cm strongly enhancing mass was detected in the head of the pancreas [Figure - 1], just posterior to the common bile duct. The tumor was homogenous, without calcification or necrosis and the peripancreatic fat was well preserved. The rest of the pancreas, adjacent stomach, duodenum and abdominal viscera were also normal. There was no adjacent lymphadenopathy.

Following the CT, an MR of the upper abdomen was performed using 3mm fat saturated T1W and TSE T2W sequences, obtained in the axial plane. On MR, the tumor was seen to be isointense on T1W images and hyperintense on T2W images [Figure - 2]. The relationship to the CBD was well demonstrated.

   Discussion Top

Insulinomas are the commonest islet cell tumors of the pancreas, followed by gastrinomas. Glucagonomas are the least common islet cell tumors [1].

The diagnosis is usually made on the basis of the classical clinical symptomatology and laboratory investigations, described as Whipple's triad. The triad consists of:

1) Spontaneous hypoglycemia followed by central nervous system and vasomotor symptoms.

2) Repeated blood glucose levels < 50 mg/dl.

3) Relief of symptoms by glucose administration.

Most insulinomas are under two cm in size. In 90% of cases, these are solitary and benign. Eight percent are multiple and these may present as diffuse hyperplasia or micro adenomatosis in 2% of cases. [2]. Insulinomas are predominantly found in the pancreatic substance, whereas gastrinomas in 28-44% of cases may be extra-pancreatic in the stomach, duodenum and lymph nodes [3].

Extra pancreatic tumors are usually small and located in the duodenal wall and are least likely to be detected pre-operatively [4]. The role of imaging is in the localization of the tumors pre-operatively. Multiple modalities are useful in the detection of islet cell tumors. However, upto 27% of islet cell tumors are not detected pre-operatively [4].

The imaging algorithm usually starts with US, followed by helical CT. Angiography and portal venous sampling may be useful in cases where CT is negative. Endoscopic US is also a newer and sensitive modality for pre-operative localization [3],[5].

Intra-operative ultrasound may be used in those cases where pre-operative localization has not been successful. [6]. It is the study of choice for localization of insulinomas and is more effective than any other pre-operative diagnostic imaging study, with a sensitivity of 90%. [1].

On CT, insulinomas and other islet cell tumors, are characteristically isodense on the plain scans and show intense enhancement following contrast administration. The enhancement is usually uniform or may be target like [2]. Unusual findings include calcification, cystic tumors and low-density tumors. [7].

Islet cell tumors often have exceptionally high relaxation times, resulting in greater conspicuity on T1W and T2W images, than most pancreatic adenocarcinomas. This is probably due to the marked edema of the stromal tissue separating nests of endocrine cells, although hypervascularity manifests as marked early enhancement after administration of contrast agents. Detection of small lesions depends on minimization of motion induced artifacts and maximization of resolution and signal to noise ratio. Hybrid fast spin echo T2 sequences may be especially effective in this regard [8].

   References Top

1.Gooding G A W; Adrenal pancreatic and scrotal ultrasound in Endocrine disease; RCNA 1993; 31: 1069-1083.   Back to cited text no. 1    
2.Haaga J R: The pancreas. In Haaga J R, Lanzieri CF et al , editors Computed Tomography and Magnetic Resonance of the whole body, 3rd Ed, St. Louis, 1994, Mosby.   Back to cited text no. 2    
3.Rosch T, Lightdale C J, Botet J F, et al , Localization of pancreatic endocrine tumors by Endoscopic Ultrasonography. New Engl J Med: 326: 1721-1726.   Back to cited text no. 3    
4.Thoeni R F, Blankenberg F.; Pancreatic imaging, Computed tomography and Magnetic Resonance imaging. RCNA 1993; 31: 1085-1113.   Back to cited text no. 4    
5.Botet J F, Lightdale C, Endoscopic ultrasonography of the upper gastrointesinal tract. RCNA 1992; 30; 1067-1083.   Back to cited text no. 5    
6.Machi J, Sigel B, Intraoperative ultrasonography. RCNA 1992; 30; 1085-1103.   Back to cited text no. 6    
7.Low-density insulinomas on dynamic CT. AJR 1990; 155: 995-996.   Back to cited text no. 7    
8.Mitchell D G. Diagnosis and staging of pancreatic tumors by magnetic resonance imaging. In Mayers M A, Ed. Neoplasms of the Digestive System, Lippincott Raven, 1998.   Back to cited text no. 8    

Correspondence Address:
Bharat Aggarwal
Diwan Chand Satya Pal Aggarwal Imaging Research Centre, 10-B, Kasturba Gandhi Marg, New Delhi 110 001
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Source of Support: None, Conflict of Interest: None

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[Figure - 1], [Figure - 2]


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