Optimum imaging of chronic pancreatitis

Chronic pancreatitis is an inflammatory process of the pancreas characterized by progressive parenchyma destruction, resulting in pain and exocrine and endocrine insufficiency. In the advanced stages the diagnosis by imaging is usually straightforward, while in the early phases of the disease there can be a paucity of findings at imaging, thus making an early diagnosis challenging. Different imaging modalities can have a role in the initial diagnosis and in the longitudinal follow-up of patients affected by chronic pancreatitis, also enabling to assess the complications of the disease. Radiography, Ultrasonography, CT and MRI can all provide morphological information, and MRI with the administration of secretin can also provide functional information. The use of an appropriate technique is fundamental for optimizing the examination to the clinical question.

Correlation between appearance of the retroportal fat plane at preoperative CT and pathology findings in resected adenocarcinoma of the pancreatic head

AIM

To correlate the appearance of the retroportal fat plane at preoperative computed tomography (CT) and the pathology findings in resected adenocarcinoma of the pancreatic head (PDAC).

MATERIAL AND METHODS

Forty-eight patients with resected PDAC of the pancreatic head were included (24 men, 24 women, mean age 63 years, median BMI 24.1). All patients underwent CT <30 days before surgery. The state of the retroperitoneal resection margin and the presence of lymphatic or perineural invasion were obtained from pathology reports. CT images were reviewed independently by two radiologists for assessment of the retroportal fat plane and graded in two categories (clear/effaced). Inter-reader discrepancies were solved in consensus. Interobserver agreement was calculated and Fisher's test was used to assess the correlation between CT and pathology findings. Visceral fat areas were measured and correlated with CT findings.

RESULTS

A clear retroportal fat plane was significantly associated with a negative retroperitoneal margin at pathology with 100% specificity and PPV (p=0.0001). No association was observed between the appearance of the fat plane at CT and the presence of lymphatic or perineural invasion (p=ns). Interobserver agreement for retroportal fat plane evaluation was good (0.741). False-positive cases had a significantly lower visceral fat area than the correctly classified patients (p=0.0480).

CONCLUSIONS

A clear retroportal fat plane is significantly associated with negative retroperitoneal resection margins at pathology. The lack of visceral adipose tissue can lead to overestimation of retroportal fat plane involvement at preoperative CT.

Bull's-eye pattern of pancreatic-duct stones on multidetector computed tomography and gene-mutation-associated pancreatitis (GMAP)

PURPOSE

This study prospectively assessed whether the presence of a bull's-eye pattern of pancreatic-duct stones on multidetector computed tomography (MDCT) correlated with gene-mutation-associated pancreatitis (GMAP) and whether other signs suggestive of GMAP can be detected with MDCT.

MATERIALS AND METHODS

Forty-seven patients with chronic calcific pancreatitis underwent genetic testing for CFTR, SPINK1 and PRSS1 mutations and an MDCT scan of the abdomen. Qualitative analysis assessed the presence or absence of pancreatic-duct stones with bull's-eye appearance. Quantitative analysis included the number and maximum diameter of stones and the diameter of the main pancreatic duct.

RESULTS

Fifteen of 47 patients (32%) were positive for gene mutations (GMAP patients). The bull's-eye pattern was found in 10/15 patients (67%) with GMAP and in 4/32 (12%) patients with chronic pancreatitis not associated with GMAP (NGMAP; p<0.0001). The mean diameter of duct stones was 15 mm in patients with GMAP and 10 mm in patients with NGMAP (p<0.04).

CONCLUSIONS

The presence of duct stones with a bull's-eye pattern correlates with GMAP. Duct stones with diameter ≥15 mm are another sign suggestive of GMAP.

Radioiodine ablation: when and how

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy with the highest mortality although with appropriate treatment has a good long-term prognosis and cure rate. Over the last 30 years there is a worldwide trend showing an increasing incidence of thyroid cancer. In DTC patients, total thyroidectomy has been for many decades routinely followed by the administration of radioiodine (131I) activity to destroy remnant thyroid tissue. Several reasons are in favour to routine ablation of postoperative thyroid remnants. The combination of both surgery and radioiodine has proven as a safe and effective treatment, resulting in improved life expectation and reduced recurrence rate for DTC patients. Recently, however, 131I ablation is not uniformly recommended for cancers smaller than 10 mm, and its use is debated for papillary tumours with diameter between 10 and 20 mm. Indeed, the decision about subsequent 131I thyroid remnant ablation is recommended as "individualized and selective". Even if new evidence has emerged that provides additional support for performing 131I treatment, the possible presence of radioiodine-associated side effects should be not overlooked. Moreover, a lot of discussion has taken place as to whether, and to what extent, 131I may cause secondary malignancies. Blood-based dosimetry is important to avoid surplus bone marrow toxicity while treating DTC patients. In this regard, the availability of a genetically engineered version of recombinant human TSH (rhTSH) provides an alternative tool to enhance serum TSH levels without inducing hypothyroidism. The administration of rhTSH to thyroid cancer patients still on LT4 therapy promotes radioiodine uptake and thyroglobulin production by thyroid cells to an extent comparable with hypothyroidism, preserving patients' quality of life, increasing the renal clearance of 131I and decreasing both the whole body and the blood dose. In this review the authors will discuss the pros and cons of postoperative radioiodine-induced thyroid remnant ablation.