OBJECTIVE-Current generation MDCT technology facilitates identification of small, nonenhancing lesions in the pancreas. The objective of this study was to determine the prevalence of findings of unsuspected pancreatic cysts on 16-MDCT in a population of adult out-patients imaged for disease unrelated to the pancreas. MATERIALS AND METHODS-Contrast-enhancedMDCT scans of the abdomen were reviewed from 2,832 consecutive examinations to identify pancreatic cysts. Patients with a history of pancreatic lesions or predisposing factors for pancreatic disease or who were referred for pancreatic CT were excluded.RESULTS-A total of 73 patients had pancreatic cysts, representing a prevalence of 2.6 per 100 patients (95% CI, 2.0-3.2). Cysts ranged in size from 2 to 38 mm (mean, 8.9 mm) and were solitary in 85% of cases. Analysis of demographic information showed a strong correlation between pancreatic cysts and age, with no cysts identified among patients under 40 years and a prevalence of 8.7 per 100 (95% CI, 4.6-12.9) in individuals from 80 to 89 years. After controlling for age, cysts were more common in individuals of the Asian race than all other race categories, with an odds ratio of 3.57 (95% CI, 1.05-12.13). There was no difference by sex in the prevalence of cysts (p = 0.527); however, cysts were on average 3.6 mm larger (p = 0.014) in men than women.CONCLUSION-In this outpatient population, the prevalence of unsuspected pancreatic cysts identified on 16-MDCT was 2.6%. Cyst presence strongly correlated with increasing age and the Asian race. KeywordsCT; incidence; MDCT; pancreatic cyst; prevalence This year an estimated 37,170 Americans will be diagnosed with pancreaticcancer, and 33,370 will die from the disease [1]. Detection of this disease in its early curable stages is difficult, to the extent that more than 80% of pancreatic cancers have metastasized or are locally unresectable at the time of diagnosis [2]. As a result, the 5-year survival rate for all stages combined is 5% [3]. The detection and treatment of early precursors to invasive pancreatic cancer offer the best hope for improving outcome.Address correspondence to K. M. Horton (E-mail: kmhorton@jhmi.edu). Three histologically distinct precursors to invasive adenocarcinoma of the pancreas have been identified. These include the intraductal papillary mucinous neoplasm, the mucinous cystic neoplasm, and pancreatic intraepithelial neoplasia [4]. Pancreatic intraepithelial neoplasias are too small to be detected by most imaging methods. However, both intraductal papillary mucinous neoplasms and mucinous cystic neoplasms should be detectable, and both appear as cystic pancreatic lesions on cross-sectional imaging [5]. This suggests that an asymptomatic cyst detected in the pancreas could represent a treatable precursor to invasive cancer. NIH Public AccessA limited number of previous studies have reported both the incidence and prevalence of pancreatic cysts across a range of patient populations using autopsy, MRI, and CT [6][7][8][9]. However, curre...

Invasive pulmonary aspergillosis (IPA) in immunocompromised patients is often difficult to diagnose. Many pathogens present initially with similar, nonspecific pulmonary findings. Air crescent formation has been reported to be highly suggestive of IPA in the appropriate clinical setting, but this is a late sign in an otherwise rapidly fatal infection. The authors reviewed the available chest computed tomography (CT) scans of nine patients with acute leukemia and documented IPA, including four patients with serial scans obtained during the course of infection. Typical CT findings of IPA were multiple inflammatory nodules, often with one large dominant mass, or a single peripheral masslike infiltrate. Cavitation or air crescent formation occurred late in the course of infection, usually at the time of bone marrow recovery from chemotherapy. CT scans obtained early in the course of infection in two patients demonstrated a distinctive feature of one or more pulmonary masslike infiltrates surrounded by a halo of low attenuation. These lesions subsequently progressed to cavitation or air crescent formation typical of IPA. While this CT halo sign may not be pathognomonic for Aspergillus, seen in the appropriate host, it may suggest early on the possibility of IPA.

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Computed tomography (CT) was used to examine 634 solitary pulmonary nodules (SPNs). Each lesion was assessed as benign or indeterminate on the basis of CT criteria. Benign nodules made up 44% of all SPNs and 58% of the 431 that were 2 cm or less in diameter. All malignant SPNs were assessed as indeterminate, and adenocarcinoma (42%) was the most common primary malignancy. A total of 176 (63% of benign SPNs) were correctly assessed as benign by CT. Ninety SPNs assessed as diffusely calcified were not so identified by conventional tomography at outside institutions. An SPN can be reliably assessed by CT as benign if it exhibits high attenuation values, exceeding a critical level and distributed diffusely throughout a CT section through the center of the lesion and a well-defined edge. Although 38 of 283 (13.4%) primary lung cancers contained localized calcification, there was no significant overlap with the diffuse calcification of benign lesions. Central carcinoid tumors may contain focal ossification, but such lesions may be recognized by noting the proximity of larger bronchi. Assessment of SPNs by CT is most effective for lesions 2.0 cm or less in diameter. For larger lesions, the frequency of benign disease was decreased (14.3% of 203), as was the percentage of benign SPNs correctly assessed as benign by CT (37.9%).

To evaluate the role of computed tomography (CT) in the investigation of pulmonary nodules, a special reference phantom that enabled CT densitometric measurements independent of variations between scanners and patients was used in ten institutions. A total of 384 nodules not considered calcified by conventional methods were examined; 118 (31%) proved to be benign, and in 65 of these (55%), unsuspected calcification was demonstrated. In 28 of the 65, definite calcification could be identified on thin-section CT scans by simple inspection of the scans at narrow windows. In the remaining 37, presence of calcification could not be clearly established without comparison with the reference CT number from the calibration phantom. CT was most effective in establishing the benignancy of nodules 3 cm or less in diameter and those with discrete or smooth margins. CT rarely yields a confident diagnosis of benign disease in larger nodules and in those with irregular or spiculated borders. After review of prior spot radiographs, low kilovolt peak spot radiographs, and conventional tomograms, the authors conclude that thin-section CT aided by a reference phantom in equivocal cases should be an integral part of the diagnostic approach to the pulmonary nodule.