Carlo Procacci

A new volumetric CT machine for dental imaging based on the cone-beam technique: preliminary results

Abstract. The objective of this paper is to present a new type of volumetric CT which uses the cone-beam technique instead of traditional fan-beam technique. The machine is dedicated to the dento-maxillo-facial imaging, particularly for planning in the field of implantology. The main characteristics of the unit are presented with reference to the technical parameters as well as the software performance. Images obtained are reported as various 2D sections of a volume reconstruction. Also, measurements of the geometric accuracy and the radiation dose absorbed by the patient are obtained using specific phantoms. Absorbed dose is compared with that given off by spiral CT. Geometric accuracy, evaluated with reference to various reconstruction modalities and different spatial orientations, is 0.8–1 % for width measurements and 2.2 % for height measurements. Radiation dose absorbed during the scan shows different profiles in central and peripheral axes. As regards the maximum value of the central profile, dose from the new unit is approximately one sixth that of traditional spiral CT. The new system appears to be very promising in dento-maxillo-facial imaging and, due to the good ratio between performance and low cost, together with low radiation dose, very interesting in view of large-scale use of the CT technique in such diagnostic applications.

Characterization of cystic tumors of the pancreas: CT accuracy.

PURPOSE The purpose of this work was to evaluate the capabilities of CT to accurately characterize cystic tumors of the pancreas. METHOD Two observers retrospectively evaluated the CT exams of 100 cystic masses of the pancreas, with pathological confirmation. The two observers, blinded about clinical information and the final diagnosis, tried to categorize the lesions according to well established morphologic features. Statistical analysis was performed to measure the agreement between each radiologist and the consensus diagnosis and to evaluate the usefulness of certain CT findings in differentiating one type of cystic pancreatic neoplasm from another. RESULTS Serous cystadenoma was better diagnosed by CT [Youden misclassification index (Ymi) = 0.72] than mucinous cystic tumor (Ymi = 0.44) and solid pseudopapillary tumor (cystic variant) (Ymi = 0.47). CONCLUSION As patients with previous history of pancreatitis were excluded from the study, CT findings allowed correct characterization of only 60% of cystic pancreatic masses. Among the remaining 40%, 15-20% of the wrong diagnoses could not be corrected by means of CT, given the patterns shown by the tumors. In 20-25% of the cases, a nonspecific diagnosis of cystic mass was made.

Congenital anomalies of the venae cavae: embryological origin, imaging features and report of three new variants

Abstract. Due to the complexity of their developmental stages, the venae cavae may undergo a very large number of congenital anomalies. All the possible abnormalities which, to our knowledge, have been observed in the literature are reported, differentiating those of the superior vena cava and the azygos system, those of the inferior vena cava and the complex anomalies that concern the venous system as a whole. Moreover, we present three new variants: a right double inferior vena cava with azygos continuation of the posterior-medial vein; an agenesis of the superior vena cava with drainage through the azygos and hemiazygos veins to the inferior vena cava; and a double inferior vena cava with hemiazygos and azygos continuation of the left one.

Serous cystadenoma of the pancreas : Report of 30 cases with emphasis on the imaging findings

PURPOSE Our goal was to evaluate retrospectively 30 cases of serous cystadenoma (SCA) to determine its main imaging features as well as to discuss the differential diagnosis problems versus the other cystic lesions of the pancreas. METHOD Thirty SCAs were analyzed; they were all benign lesions, proven at surgery. Twenty-three tumors were evaluated with US, 26 with CT, and 5 with MRI. RESULTS Three different morphostructural patterns were identified: microlacunar (n = 19), mixed (n = 6), and macrolacunar (n = 5). The diagnosis of SCA, possible in either the microlacunar or the mixed patterns, was achieved in 74% of cases with US (17/23) and in 61.5% with CT (16/26). Among the 19 patients evaluated with both modalities, the joint information allowed a correct diagnosis in 16 cases (84%). The five macrolacunar tumors were undistinguishable from other cystic masses of the pancreas. CONCLUSION The diagnosis of SCA can be considered certain in the microlacunar, likely in the mixed, and not possible in the macrolacunar type.

Neuroendocrine pancreatic tumor: value of contrast enhanced ultrasonography.

The recently introduced contrast-enhanced ultrasonography (CEUS) has led to a great development in the diagnostic abilities of US. Second-generation contrast media, characterized by harmonic responses at low acoustic pressures (low mechanical index) of the US beam, have proved their usefulness in the study of the liver, but other abdominal organs can benefit from the dynamic study that derives from the nonlinear response during continuous US scans. The study of the pancreas is a new and promising application of CEUS, especially in the evaluation of hypervascular lesions, such as neuroendocrine pancreatic tumors. Neuroendocrine tumors, or islet cell tumors, of the pancreas originate from multipotential stem cells that have retained the ability to proliferate and differentiate into various cellular lines that make up this group of neoplasms. They account for about 1% to 2% of all pancreatic tumors [1]. Most of these tumors can be clinically diagnosed because they secrete one or more active peptides that produce clinical symptoms. These neuroendocrine tumors are called functioning islet cell tumors. The clinical manifestations of these tumors appear early, when very small in dimension, so that preoperative localization with noninvasive imaging can be difficult to obtain. Conversely, when not symptomatic because of the lack of active peptide secretion, neuroendocrine tumors of the pancreas can grow slowly, without significant or specific clinical manifestations. These neuroendocrine tumors are called nonfunctioning islet cell tumors (NEFTs). Because they are not specifically symptomatic, the characterization of these pancreatic tumors is often entrusted to imaging and results from the identification of their hypervascular architecture. Moreover, an accurate differential diagnosis is needed because of the favorable responses to surgery and specific chemotherapy of these tumors, with a better prognosis than with ductal adenocarcinoma. We discuss the possibilities of CEUS in the study of neuroendocrine pancreatic tumors.

Nonfunctioning endocrine tumors of the pancreas: Possibilities of spiral CT characterization

Abstract. The aim of this study was to assess the ability of spiral CT to adequately characterize the nonfunctioning endocrine tumors (NFETs) of the pancreas, distinguishing this lesion from the other pancreatic tumors. The spiral CT examinations of 21 cases of histologically proven NFETs, along with those of 29 cases of other pancreatic tumors and tumor-like lesions, were retrospectively reviewed in a blinded fashion by two radiologists, in order to correctly classify the lesions, highlighting the typical signs reported in the literature. Discordant cases were further analyzed in the presence of a third radiologist. The final diagnosis was acquired by means of a majority or overall consensus. The histopathologic examination was considered the gold standard. The sensitivity, specificity, and positive and negative predictive values of CT were calculated. After the consensus evaluation, the correct diagnosis was reached in 72% of cases, with 10% of nonspecific diagnoses of solid pancreatic tumor and 18% of wrong diagnoses. The sensitivity and specificity of spiral CT in identifying NFETs were 66.6 and 82.7%, respectively. The positive and negative predictive values were 73.7 and 77.4%, respectively. In up to 70% of cases the NFET demonstrates a typical aspect of a mass hyperdense in the arterial contrastographic phase eventually associated with hyperdense hepatic metastases in more than half of the patients. This finding does allow the diagnosis of NFET but without certainty indeed, since other tumors can show a similar densitometric behavior and among them particularly the ductal adenocarcinoma. On the other hand, both the solid, hypovascularized NFETs, and the cystic form, cannot be differentiated from the other solid and cystic tumors of the pancreas.

Autoimmune Pancreatitis: Possibilities of CT Characterization

Background: Pancreatitis is defined as an inflammatory disease of the pancreas, leading to morphological and pathological changes. Recently, an autoimmune pathogenesis of this disease has been proposed. This type of pancreatitis should be differentiated from other pancreatic diseases, since appropriate therapy is effective and morphological changes and pancreatic function can recover to normal levels. Aim of the Study: To assess the possibility of distinguishing autoimmune pancreatitis from other pancreatic diseases with an analogous clinical presentation on the basis of CT findings alone. Methods: The CT images of 7 patients with proven autoimmune pancreatitis, along with those of 20 patients with other pancreatic diseases, but with an analogous clinical presentation, were retrospectively evaluated in a blinded fashion by 2 radiologists. In particular, the radiologists had to search for the typical signs of autoimmune pancreatitis. Discordant cases were further analyzed in the presence of a 3rd radiologist. The final diagnosis was acquired by means of a majority or overall consensus. The sensitivity, specificity, positive and negative predictive values of CT were calculated against each of the diseases (autoimmune pancreatitis; other pancreatic diseases), in order to evaluate the diagnostic value of the scan. Results: After the consensus evaluation, the correct diagnosis was reached in 25/27 (92.5%) cases, with only 2/27 wrong diagnoses (autoimmune pancreatitis diagnosed as another pancreatic disease and vice versa). The sensitivity and specificity of CT against autoimmune pancreatitis were 86 and 95%, respectively. The positive and negative predictive values were 89 and 93%, respectively. Conclusion: Patients with autoimmune pancreatitis demonstrate imaging findings that enable the correct diagnosis by dynamic CT, even in the presence of nonspecific clinical symptoms. The precise classification of the disease is extremely important, since simple steroid therapy then represents the correct treatment, and leads to complete recovery.

Intraductal papillary mucinous tumors of the pancreas: spectrum of CT and MR findings with pathologic correlation.

Abstract. The reports of intraductal papillary mucinous tumors (IPMT) of the pancreas are increasingly more frequent in the literature. The diagnosis by means of cross-sectional imaging of these tumors is not easy, especially in the early stages, when they can mimic an inflammatory disease of the pancreas. Prompt identification of the disease is nevertheless extremely important, especially in the case of tumors originating from the collateral branches, since its recognition can modify the management of the patient, in some cases obviating recourse to surgery.

MRI of focal nodular hyperplasia (FNH) with gadobenate dimeglumine (Gd-BOPTA) and SPIO (ferumoxides): An intra-individual comparison

To compare the efficacy of two different MR contrast agents for the detection and diagnosis of focal nodular hyperplasia (FNH).

Thoracic Complications of Pancreatitis

Pancreatitis may be associated with thoracic complications, notably chronic massive pleural effusion (CMPE) and, rarely, pseudocysts with mediastinal extension (PME) and enzymatic mediastinitis (EM). Our personal experience with 14 cases of thoracic complications (nine CMPE, two PME associated with pleural effusion, and three EM of 670 patients who underwent surgery; of these, 191 had acute and 479 had chronic pancreatitis) during 16 years (1970–1986) is reported. In the patients with CMPE, the initial symptoms were progressive dyspnea eventually associated with cough and chest pain. In the PME cases, there was dysphagia associated with left subscapular pain and left chest pain. The initial signs in the patients with EM were sudden dyspnea, cyanosis, retrosternal pain, tachycardia, and acute heart failure. A fistula between the pancreatic ductal system and the pleural cavity in seven of the nine patients with CMPE was demonstrated by intraoperative pancreatography and/ or cystography. On the contrary, preoperative endoscopic pancreatography demonstrated the sinus tract in only three of the seven. In both cases of PME, computed tomography (CT) provided a correct diagnosis that was confirmed at surgery. In the patients with EM, the diagnosis was suggested by the clinical appearance and was confirmed by the chest roentgenogram and by CT. All patients had operations after varying periods of unsuccessful 2–4-week-long conservative treatment. One patient with infected ascites died postoperatively. There were no thoracic recurrences of pancreatic disease among the other patients at a 10-month-10-year follow-up observation after surgery.