Figure 1
3D-MIP reconstruction MRCP image
There are two strictures within the main pancreatic duct, at the neck measuring 13 mm in length and at the level of the pancreatic body measuring 6 mm in diameter, respectively.
Multifocal metastatic pancreatic neuroendocrine tumour
SectionAbdominal imaging
Case TypeClinical Cases
AuthorsR. Severino1, J. Parikh2
Connected authors
63 years, male
Clinical History
A 63-year-old patient, with a previous non-Hodgkin's lymphoma currently in remission, presented with right upper quadrant pain. An US showed a lesion in the head of the pancreas and liver lesions.
A contrast-enhanced CT confirmed these findings, but also showed unexplained pancreatic duct dilatation. Contrast-enhanced MR and MRCP were performed.
A contrast-enhanced CT confirmed these findings, but also showed unexplained pancreatic duct dilatation. Contrast-enhanced MR and MRCP were performed.
Imaging Findings
MRCP showed two strictures within the main pancreatic duct, one in the neck and the other in the body of the pancreas. T2-weighted (T2W) and T1-weighted (T1W) contrast-enhanced MRI showed poorly-enhancing small lesions (individually measuring up to 15 mm) related to these two strictures. In addition to the conventional MR sequences, diffusion-weighted images (DWI) were also performed. They showed at least six areas of high signal intensity on high-b value images along the length of the pancreatic duct, corresponding to low signal areas on ADC maps. These findings were in keeping with the presence of pancreatic solid lesions associated with high cellularity areas and restriction of extracellular water. In the liver there were at least 6 poorly enhancing target-like lesions with central cystic/necrotic components, suspected to be metastases from the pancreatic lesions.
The patient underwent an ultrasound-guided liver biopsy of the largest of these liver lesions to confirm the histological diagnosis.
The patient underwent an ultrasound-guided liver biopsy of the largest of these liver lesions to confirm the histological diagnosis.
Discussion
Pancreatic neuroendocrine tumours (PNETs) are the second most common solid pancreatic tumours, which account for 1-5% of all solid pancreatic neoplasms. Most patients are aged 51-57 years, with equal gender distribution. They have an indolent growth pattern and do not typically cause biliary and pancreatic ductal obstruction.
PNETs are classified into functioning and non-functioning as they can release hormones, which cause specific symptoms. [1, 2]
Up to 50% of PNETs are related to specific clinical syndromes; therefore the diagnosis of PNETs is based mainly on clinical and biochemical parameters. The role of the imaging is to aid the diagnosis and to localize the tumour for image-guided biopsy, surgery and/or further treatment and follow-up. The radiological assessment is more important in non-functioning PNET than in functioning PNET, as these can present as incidental findings in a patient with non-specific abdominal pain, often related to their mass effect, and differential diagnosis with adenocarcinoma is needed. [1-3]
They are rarely associated with pancreatic duct stenosis, as in this case, and the patient may present with symptoms of pancreatitis as a result. This uncommon finding has been described mostly in non-functioning PNET [4].
Surgical resection is the standard treatment for these tumours with a variable 5-year overall survival: >50% for non-functioning PNETs and >90% for functioning PNETs [1-3].
At imaging evaluation, lesions are usually well-defined. They are typically hypointense on T1W, hyperintense on T2W images, with early avid enhancement in the arterial phase. Large PNETs are known to develop central necrotic degeneration and show more heterogeneous, late enhancement [2-5]. The small pancreatic lesions seen in this case were unusual as they showed cystic change and later heterogeneous enhancement in keeping with poorly-differentiated tumours.
In this case, the DWI was helpful in identifying other lesions which were all small (<15mm) and difficult to see on the standard T2W and post-contrast T1W-imaging. It was demonstrated that DWI may depict small solid masses better than routine MR imaging due to its greater image contrast, despite its poorer spatial resolution and low specificity.
High signal intensity on DWI with high b-value and low ADC values are consistent with a restricted diffusion of high cellularity lesions. However, these findings may be present in various focal pancreatic lesions such as either poorly differentiated adenocarcinoma or mass-forming pancreatitis [6-7].
Therefore DW-MRI represents a useful adjunct for atypical small NET detection, but correlation with the clinical picture and conventional MR imaging is still recommended.
PNETs are classified into functioning and non-functioning as they can release hormones, which cause specific symptoms. [1, 2]
Up to 50% of PNETs are related to specific clinical syndromes; therefore the diagnosis of PNETs is based mainly on clinical and biochemical parameters. The role of the imaging is to aid the diagnosis and to localize the tumour for image-guided biopsy, surgery and/or further treatment and follow-up. The radiological assessment is more important in non-functioning PNET than in functioning PNET, as these can present as incidental findings in a patient with non-specific abdominal pain, often related to their mass effect, and differential diagnosis with adenocarcinoma is needed. [1-3]
They are rarely associated with pancreatic duct stenosis, as in this case, and the patient may present with symptoms of pancreatitis as a result. This uncommon finding has been described mostly in non-functioning PNET [4].
Surgical resection is the standard treatment for these tumours with a variable 5-year overall survival: >50% for non-functioning PNETs and >90% for functioning PNETs [1-3].
At imaging evaluation, lesions are usually well-defined. They are typically hypointense on T1W, hyperintense on T2W images, with early avid enhancement in the arterial phase. Large PNETs are known to develop central necrotic degeneration and show more heterogeneous, late enhancement [2-5]. The small pancreatic lesions seen in this case were unusual as they showed cystic change and later heterogeneous enhancement in keeping with poorly-differentiated tumours.
In this case, the DWI was helpful in identifying other lesions which were all small (<15mm) and difficult to see on the standard T2W and post-contrast T1W-imaging. It was demonstrated that DWI may depict small solid masses better than routine MR imaging due to its greater image contrast, despite its poorer spatial resolution and low specificity.
High signal intensity on DWI with high b-value and low ADC values are consistent with a restricted diffusion of high cellularity lesions. However, these findings may be present in various focal pancreatic lesions such as either poorly differentiated adenocarcinoma or mass-forming pancreatitis [6-7].
Therefore DW-MRI represents a useful adjunct for atypical small NET detection, but correlation with the clinical picture and conventional MR imaging is still recommended.
Differential Diagnosis List
Pancreatic neuroendocrine tumour
Pancreatic adenocarcinoma: aggressive tumour
commonly presenting with painless obstructive jaundice with biliary and pancreatic duct dilatation. Lesions are typically unifocal and ill-defined
showing low signal intensity on T1W and T2W MRI
and a hypovascular pattern on contrast-enhanced T1W images
Metastases from unknown primary
Final Diagnosis
Pancreatic neuroendocrine tumour
References
[1] Low G, Panu A, Millo N, Leen E. (2011) Multimodality imaging of neoplastic and nonneoplastic solid lesions of the pancreas. Radiographics Jul-Aug;31(4):993-1015 (PMID: 21768235)
[2] Lewis RB, Lattin GE Jr, Paal E. (2010) Pancreatic endocrine tumors: radiologic-clinicopathologic correlation. Radiographics Oct;30(6):1445-64 (PMID: 21071369)
[3] Sahani DV, Bonaffini PA, Fernández-Del Castillo C, Blake MA. (2013) Gastroenteropancreatic neuroendocrine tumors: role of imaging in diagnosis and management. Radiology Jan;266(1):38-61 (PMID: 23264526)
[4] Jukemura J, Montagnini AL, Perini MV, de Almeida JL, Rodrigues JJ, da Cunha JE. (2006) Acute pancreatitis associated with neuroendocrine tumor of the pancreas. JOP Jan 11;7(1):56-61. (PMID: 16407620)
[5] Herwick S, Miller FH, Keppke AL. (2006) MRI of islet cell tumors of the pancreas. Am J Roentgenol Nov;187(5):W472-80 (PMID: 17056877)
[6] Schmid-Tannwald C, Schmid-Tannwald CM, Morelli JN, Neumann R, Haug AR, Jansen N, Nikolaou K, Schramm N, Reiser MF, Rist C. (2013) Comparison of abdominal MRI with diffusion weighted imaging to 68Ga-DOTATATE PET/CT in detection of neuroendocrine tumors of the pancreas. Eur J Nucl Med Mol Imaging Jun;40(6):897-907 (PMID: 23460395)
[7] Wang Y(1), Miller FH, Chen ZE, Merrick L, Mortele KJ, Hoff FL, Hammond NA, Yaghmai V, Nikolaidis P. (2011) Diffusion-weighted MR imaging of solid and cystic lesions of the pancreas. Radiographics May-Jun;31(3):E47-64 (PMID: 21721197)
Case information
| URL: | https://www.eurorad.org/case/12429 |
| DOI: | 10.1594/EURORAD/CASE.12429 |
| ISSN: | 1563-4086 |
Figure 2
Axial T2 weighted HASTE MR image of the liver
Axial T2 weighted MR image shows two large ring-like liver lesions. They are mostly hyperintense but with a central area of higher T2 signal intensity likely due to a cystic/necrotic component.
Figure 3
Axial ADC map
ADC map shows at least 4 low signal areas, corresponding to areas of restriction of water diffusion, related to the presence of high cellularity lesions.
Figure 4
Post-contrast axial fat-sat T1W MR image, early arterial phase
Axial arterial phase T1 weighted MR image shows hypoenhancing lesion at the tail of the pancreas.
Figure 5
Post-contrast axial fat sat T1W MR image, portal-venous phase
Axial portal-venous phase T1 weighted MR image shows hypoenhancing lesion at the tail of the pancreas.
3D-MIP reconstruction MRCP image
There are two strictures within the main pancreatic duct, at the neck measuring 13 mm in length and at the level of the pancreatic body measuring 6 mm in diameter, respectively.
Department of Radiology, Guy\'s and St Thomas\' Hospitals NHS Foundation Trust, London, England
Department of Radiology, Guy\'s and St Thomas\' Hospitals NHS Foundation Trust, London, England
Axial T2 weighted HASTE MR image of the liver
Axial T2 weighted MR image shows two large ring-like liver lesions. They are mostly hyperintense but with a central area of higher T2 signal intensity likely due to a cystic/necrotic component.
Department of Radiology, Guy\'s and St Thomas\' Hospitals NHS Foundation Trust, London, England
Department of Radiology, Guy\'s and St Thomas\' Hospitals NHS Foundation Trust, London, England
Axial ADC map
ADC map shows at least 4 low signal areas, corresponding to areas of restriction of water diffusion, related to the presence of high cellularity lesions.
Department of Radiology, Guy\'s and St Thomas\' Hospitals NHS Foundation Trust, London, England
Department of Radiology, Guy\'s and St Thomas\' Hospitals NHS Foundation Trust, London, England
Post-contrast axial fat-sat T1W MR image, early arterial phase
Axial arterial phase T1 weighted MR image shows hypoenhancing lesion at the tail of the pancreas.
Department of Radiology, Guy’s and St Thomas’ Hospitals NHS Foundation Trust, London, England
Department of Radiology, Guy’s and St Thomas’ Hospitals NHS Foundation Trust, London, England
Post-contrast axial fat sat T1W MR image, portal-venous phase
Axial portal-venous phase T1 weighted MR image shows hypoenhancing lesion at the tail of the pancreas.
Department of Radiology, Guy’s and St Thomas’ Hospitals NHS Foundation Trust, London, England
Department of Radiology, Guy’s and St Thomas’ Hospitals NHS Foundation Trust, London, England