Diffusion weighted MR imaging of pancreatic islet cell tumors

Purpose

The aim of our study is to demonstrate the feasibility of body diffusion weighted (DW) MR imaging in the evaluation of pancreatic islet cell tumors (ICTs) and to define apparent diffusion coefficient (ADC) values for these tumors.

Materials and methods

12 normal volunteers and 12 patients with histopathologically proven pancreatic ICT by surgery were included in the study. DW MR images were obtained by a body-phased array coil using a multisection single-shot echo planar sequence on the axial plane without breath holding. In addition, the routine abdominal imaging protocol for pancreas was applied in the patient group. We measured the ADC value within the normal pancreas in control group, pancreatic ICT, and surrounding pancreas parenchyma. Mann-Whitney U-test has been used to compare ADC values between tumoral tissues and normal pancreatic tissues of the volunteers. Wilcoxon Signed Ranks Test was preferred to compare ADC values between tumoral tissues and surrounding pancreatic parenchyma of the patients.

Results

In 11 patients out of 12, conventional MR sequences were able to demonstrate ICTs succesfully. In 1 patient an indistinct suspicious lesion was noted at the pancreatic tail. DW sequence was able to demonstrate the lesions in all of the 12 patients. On the DW images, all ICTs demonstrated high signal intensity relative to the surrounding pancreatic parenchyma. The mean and standard deviations of the ADC values (×10⁻³ mm²/s) were as follows: ICT (n = 12), 1.51 ± 0.35 (0.91-2.11), surrounding parenchyma (n = 11) 0.76 ± 0.15 (0.51-1.01) and normal pancreas in normal volunteers (n = 12), 0.80 ± 0.06 (0.72-0.90). ADC values of the ICT were significantly higher compared with those of surrounding parenchyma (p < 0.01) and normal pancreas (p < 0.001).

Conclusion

DW MR imaging does not appear to provide significant contribution to routine MR imaging protocol in the evaluation of pancreatic islet cell tumors. But it can be added to MR imaging protocol to detect the lesion in a limited number of patients with clinical suspicion for pancreatic ICT with negative or suspicious imaging findings.     

胰岛细胞瘤的CT和MRI表现

目的:探讨胰岛细胞瘤的CT和MRI表现。方法:对9例手术证实的胰岛细胞瘤的CT和MRI表现进行回顾性分析,其中功能性胰岛细胞瘤7例,无功能性胰岛细胞瘤2例。结果:9例胰岛细胞瘤均富血供,边界清楚,与周围胰腺分界清楚,无血管、胰管侵犯。功能性胰岛细胞瘤多较小,无功能性胰岛细胞瘤较大。结论:胰岛细胞瘤有典型的CT和MRI表现,CT和MR增强扫描能准确诊断胰岛细胞瘤。     

Computed tomographic diagnosis of primary mediastinal tumors

61 Patients with histologically proved primary mediastinal tumour were examined by computed tomography (CT) of the thorax prior to surgery. The retrospective analysis of the CT scans led to the correct diagnosis in 77% of cases. CT-values (HE), calcifications or form of tumour growth was found to be unreliable in the classification of tumour status.     

胰岛细胞瘤的MSCT表现

胰岛细胞瘤是少见的胰腺神经内分泌性肿瘤。笔者搜集我院经手术与病理证实的胰岛细胞瘤8例,并复习相关文献,对其MSCT表现进行回顾性分析和总结。     

Computed tomographic detection of a swallowed denture

A 89-year-old, nursing home female presented with a two-week history of drooling and a hard palpable mass in the region of the larynx. Initial fiberoptic laryngoscopy revealed a hard pinkish-white mass which was felt to represent a tumor. Computed tomography demonstrated swallowed, impacted, complete, mandibular denture. Radiologists should be aware of this problem, particularly in the elderly demented patient.     

Computed tomographic detection of a small bowel carcinoid

Carcinoid tumors are localized in the terminal ileum, in the appendix, in the stomach-duodenum and the colon. The local infiltrative process provokes an intense fibro-sclerotic reaction in the mesentery. In 30% of the cases they cause metastases in the lymph nodes, in the liver and seldom in the lungs. We describe a patient with symptoms of incomplete obstruction who had a mass in the right abdominal quadrant. CT showed an ileal tumor with fibro-sclerotic infiltration of the mesentery, typical of carcinoid tumor, and metastases in cardiophrenic angle nodes.     

Extracranial and extraspinal nerve sheath tumors: Computed tomographic evaluation

Summary Thirty-five patients with 37 peripheral nerve sheath tumors (NST) (16 schwannomas, 11 neurofibromas, 5 plexiform and 1 diffuse neurofibroma, and 4 malignant NST) were studied respectively. The benign NST usually appeared on CT as well-defined oval, spherical or fusiform masses, centered at the expected anatomic location of a cranial, spinal, autonomic or peripheral nerve with characteristic displacement of adjacent muscles and blood vessels. None of the schwannomas appeared homogeneously hypodense on IV enhanced CT, whereas close to half of neurofibromas and plexiform neurofibromas were so. This fact, which had not been reported in the past, may be related to differences in inherent vascularity and blood-nerve barrier (fenestrated blood vessels) between schwannomas and neurofibromas and may be a useful distinguishing CT feature. The most reliable, though not infallible criterion of malignant NST was poor definition of their margins. Ninety-two per cent of NST (34 out of 37) were diagnosed or included in a limited differential pre-operatively.     

Computed tomographic detection of skeletal muscle calcifications in rhabdomyolysis.

The authors report a case of rhabdomyolysis with extensive calcification of the paravertebral muscles secondary to ingestion of desipramine hydrochloride, a tricyclic antidepressant. Computed tomography (CT) and isotope scanning were performed, and pathological confirmation of the condition was obtained. The extent of the calcification was probably due to the administration of supplementary calcium to correct hypocalcemia. The authors discuss the correlation between the CT and isotope scan findings.     

Computed tomographic arteriography

Computed tomographic arteriography is the technique of contrast enhancement by arterial perfusion during computed tomography. This technique appears to have significant advantages over conventional intravenous contrast enhancement in selected cases.     

Computed tomographic and nuclear spin tomographic diagnosis of brain tumors using conventional and paramagnetic contrast media

52 patients with cerebral tumours were examined by both CT and MR. Contrast media containing iodine were used in CT, whereas in MR a paramagnetic contrast medium (gadolinium-DTPA) was applied by IV injection. A comparison of CT and MR findings showed that with both methods it was often not possible to achieve sufficient visualization and delineation of tumour tissue without employing a contrast medium. After application of the contrast medium, the shape and size contrast enhancement in the tumour tissue in both CT and MR was practically identical. This enables direct visualization of the tumour, superior delineation from the adjacent tissue, and differentiation between oedema and tumour, resulting in effective treatment planning which would otherwise not be possible.     

Calcified liver metastases from a calcified pancreatic vipoma. Computed tomographic visualization

A female patient with an 18-month history of watery diarrhea was studied. Computed tomography was performed, revealing a totally calcified tumor of the pancreas and multiple calcified liver metastases. Liver biopsy was done and the diagnosis of a metastatic vipoma was confirmed.