BackgroundThe aim is to assess the time-density curves (TDCs) and correlate the histologic results for small (≤ 2 cm) PDA and surrounding parenchyma at triphasic Multidetector-row CT (MDCT).MethodsTriphasic MDCT scans of 38 consecutive patients who underwent surgery for a small PDA were retrospectively reviewed. The TDCs were analyzed and compared with histologic examination of the PDA and pancreas upstream/downstream in all cases. Three enhancement patterns were identified: 1) enhancement peak during pancreatic parenchymal phase (PPP) followed by a rapid decline on portal venous phase (PVP) and delayed phase (DP) at 5 minutes (type 1 pattern: normal pancreas); 2) maximum enhancement in PVP that gradually decreases in DP (type 2 pattern: mild chronic pancreatitis or PDA with mild fibrous stroma); 3) progressive enhancement with maximum peak in DP (type 3 pattern: severe chronic pancreatitis or PDA with severe fibrous stroma). A p value less than 0.05 was considered statistically significant. Sensitivity was calculated for PDA detection and an attenuation difference with the surrounding tissue of at least 10 HU was considered.ResultsPDA showed type 2 pattern in 5/38 cases (13.2%) and type 3 pattern in 33/38 cases (86,8%). Pancreas upstream to the tumor had type 2 pattern in 20/38 cases (52,6%) and type 3 pattern in 18/38 cases (47,4%). Pancreas downstream to the tumor had type 1 pattern in 19/25 cases (76%) and type 2 pattern in 6/25 cases (24%). Attenuation difference between tumor and parenchyma upstream was higher of 10 UH on PPP in 31/38 patients (sensitivity = 81.6%), on PVP in 29/38 (sensitivity = 76.3%) and on DP in 17/38 (sensitivity = 44.7%). Attenuation difference between tumor and parenchyma downstream was higher of 10 UH on PPP in 25/25 patients (sensitivity = 100%), on PVP in 22/25 (sensitivity = 88%) and on DP in 20/25 (sensitivity = 80%). Small PDAs were isodense to the pancreas upstream to the tumor, and therefore unrecognizable, in 8 cases (8/38; 21%) at qualitative analysis and in 4 cases (4/38; 10,5%) at quantitative analysis.ConclusionsThe quantitative analysis increases the sensitivity for detection of small PDA at triphasic MDCT.

The incidence of neuroendocrine tumors is rising, and this rise is explained by more than just better diagnostic procedures. About 85% of these neoplasms arise in gastrointestinal or pulmonary sites, but cases where the location is more unusual also occur in clinical practice. The tailgut cyst is a rare entity well described in the medical literature, but a neuroendocrine tumor within such a cyst is a very rare event, with about 30 cases described in the literature to date. In this report we present the case of a young woman with this unusual diagnosis. The characteristics of the case differ from most previous case reports in a few respects: the patient was a young rather than middle-aged female; she had a presacral mass with a significant solid component; at diagnosis, there was evidence of a lytic lesion in the coccyx. Despite this particular medical presentation, radical surgery was accomplished. In this disease the greatest risk is local relapse, but adjuvant radiotherapy may compromise the patient's fertility. We therefore opted for strict control only, but this decision might be debatable.

Respiratory involvement of COVID-19 infection, with presentations ranging from a mild flu-like illness to 31 potentially lethal acute respiratory distress syndrome, is the main clinical manifestation in adults. Chest 32 imaging shows a pictorial fashion of images due to the severity and stage of the disease, starting from 33 focal nodular or mass-like opacities with air bronchogram to areas of ground glass consolidation or 34 whited out lung. However, during the COVID-19 pandemic, CT findings could yield confounding reporting 35 in the case of cancer patients previously treated with thoracic radiotherapy (tRT) due to atypical radiation 36 pneumonitis occurring outside the radiation ports. Hypersensitivity pneumonitis and radiation-induced 37 bronchiolitis obliterans organizing pneumonitis (RT-BOOP) are accounted for in this report. 38

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