Niccolò Faccioli

Ultrasonography of the pancreas. 4. Contrast-enhanced imaging

The introduction of contrast-enhanced ultrasonography (CEUS) has lead to great developments in the diagnostic capabilities of ultrasound. Second generation contrast media, characterized by harmonic responses at low mechanical index of the ultrasound beam, have already proven usefulness in the study of the liver but other abdominal organs can take advantage from the dynamic study during continuous ultrasonographic scans. The dynamic observation of the enhancement allows the perfect evaluation of the abdominal organs perfusion. The perfusion of the pancreas is well correlated to the semeiology of the gland parenchymography at CEUS. The study of the pancreas is a new and promising application of CEUS. CEUS can be used to better identify pancreatic lesions respect to conventional Ultrasound (US) or to characterize pancreatic lesions already visible at US. Moreover the staging of some pancreatic lesions can be improved by the use of contrast media. This article will review the clinical application of CEUS in the different pancreatic pathologies.

Solid hypervascular liver lesions: accurate identification of true benign lesions on enhanced dynamic and hepatobiliary phase magnetic resonance imaging after gadobenate dimeglumine administration.

Purpose:To evaluate hepatobiliary phase magnetic resonance imaging with gadobenate dimeglumine for differentiation of benign hypervascular liver lesions from malignant or high-risk lesions. Methods and Materials:Retrospective assessment was performed of 550 patients with 910 hypervascular lesions (302 focal nodular hyperplasia [FNH], 82 nodular regenerative hyperplasia [NRH], 59 hepatic adenoma or liver adenomatosis [HA/LA], 329 hepatocellular carcinomas [HCC], 12 fibrolamellar-HCC [FL-HCC], 21 peripheral cholangiocarcinomas [PCC], 105 metastases). Imaging was performed before and during the arterial, portal-venous, equilibrium, and hepatobiliary phases after gadobenate dimeglumine administration (0.05 mmol/kg). Histologic confirmation was available for ≥1 lesion per patient, except for patients with suspected FNH (diagnosis based on characteristic enhancement/follow-up). Lesion differentiation (benign/malignant) on the basis of contrast washout and lesion enhancement (hypo-/iso-/hyperintensity) was assessed (sensitivity, specificity, accuracy, PPV, and NPV) relative to histology or final diagnosis. Results:On portal-venous or equilibrium phase images, washout was not seen for 208 of 526 (39.5%) malignant (HCC, FL-HCC, PCC, metastases) and high-risk (HA/LA) lesions. Conversely, only 5 of 384 (1.3%) true benign lesions (FNH/NRH) showed washout. Taking washout as indicating malignancy, the sensitivity, specificity, and accuracy for malignant lesion identification during these phases was 61.8%, 98.7%, and 77.4%. On hepatobiliary phase images, 289 of 302 FNH, 82 of 82 NRH, 1 of 59 HA or LA, 62 of 341 HCC or FL-HCC, and 2 of 105 metastases were hyperintense or isointense. Taking iso- or hyperintensity as an indication for lesion benignity, the sensitivity, specificity, accuracy, PPV, and NPV for benign lesion identification was 96.6%, 87.6%, 91.4%, 85.1%, and 97.3%, respectively. Conclusions:Hepatobiliary phase imaging with gadobenate dimeglumine is accurate for distinguishing benign lesions from malignant or high-risk lesions. Biopsy should be considered for hypointense lesions on hepatobiliary phase images after gadobenate dimeglumine.

Comparison of contrast-enhanced sonography and MRI in displaying anatomic features of cystic pancreatic masses.

OBJECTIVE The purpose of this study was to compare the accuracy rates of unenhanced sonography, contrast-enhanced sonography, and MRI in displaying the anatomic features of cystic pancreatic masses larger than 1.5 mm in diameter. MATERIALS AND METHODS Unenhanced and contrast-enhanced sonographic and MRI examinations of 33 patients who underwent resection of a cystic pancreatic mass were retrospectively reviewed. Two radiologists blinded to the final histologic diagnosis reviewed the images, specifically assessing the presence of intralesional mural nodules and septa. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated on the basis of correlation with surgical findings. Results of unenhanced sonography, contrast-enhanced sonography, and MRI were compared by McNemar test. Correlation of unenhanced and contrast-enhanced sonographic versus pathologic results was established with Spearmans test. Interobserver variability was determined. RESULTS Contrast-enhanced sonography correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 88.8%; positive predictive value, 87.5%; negative predictive value, 94.1%; accuracy, 90.9%) and nodules in six of eight lesions (sensitivity, 75%; specificity, 96%; positive predictive value, 85.7%; negative predictive value, 92.3%; accuracy, 90.9%). MRI correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 61.1%; positive predictive value, 66.6%; negative predictive value, 91.6%; accuracy, 75.7%) and nodules in seven of eight lesions (sensitivity, 87.5%; specificity, 80%; positive predictive value, 58.3%; negative predictive value, 95.2%; accuracy, 81.8%). The difference between the diagnostic accuracy of contrast-enhanced sonography and that of MRI was not significant (p = 0.05, McNemar test) in the identification of septa and nodules. The correlation between contrast-enhanced sonographic findings and pathologic results (Rs = 0.93; p < 0.001) was significantly better than that between sonographic and pathologic results (Rs = 0.52; p < 0.0001). Interobserver agreement had a kappa value of 0.86-0.94. CONCLUSION Contrast-enhanced sonography compares favorably with MRI in displaying the anatomic features of cystic pancreatic masses seen on transabdominal sonography.

Contrast-enhanced sonography of nonfunctioning pancreatic neuroendocrine tumors.

OBJECTIVE Diagnosis of malignancy and prognostic assessment continue to be problems in the management of nonfunctioning pancreatic endocrine tumors. Histologic examination is the reference standard. The aim of our study was to compare B-mode and contrast-enhanced sonographic findings regarding nonfunctioning pancreatic endocrine tumors. Signs of malignancy, such as Ki67 index and presence of hepatic metastasis, were considered. MATERIALS AND METHODS We retrospectively reviewed the cases of 38 consecutively registered patients with nonfunctioning pancreatic endocrine tumors evaluated with B-mode and contrast-enhanced sonography and resected. At contrast-enhanced sonography all lesions were divided into hypovascular lesions and isovascular or hypervascular lesions. On the basis of homogeneity of enhancement, lesions were classified as homogeneous and inhomogeneous. During the late phase of contrast enhancement, all solid focal hypoechoic liver lesions detected at contrast-enhanced sonography were considered hepatic metastatic lesions. Among pathologic data, grading, mitotic index, and Ki67 index were evaluated. Spearmans test was used to compare contrast-enhanced sonographic enhancement pattern with pathologic grade. RESULTS In the arterial phase, 24 of 38 nonfunctioning pancreatic endocrine tumors (63.1%) were hypervascular, seven (18.4%) were isovascular, and seven (18.4%) were hypovascular. Positive correlation was found between contrast-enhanced sonographic findings and Ki67 index (r(s) = 0.62; p < 0.0001). The difference between contrast-enhanced and B-mode sonography in the diagnosis of nonfunctioning pancreatic endocrine tumors was statistically significant (p < 0.05). Use of contrast-enhanced sonography increased diagnostic confidence in the detection of hepatic metastasis. The areas under the receiver operating characteristic curves were 0.916 for B-mode sonography and 1.000 for contrast-enhanced sonography (p < 0.05). There was moderate positive correlation between contrast-enhanced sonographic enhancement pattern and the presence of hepatic metastasis at diagnosis (r(s) = 0.46; p = 0.004) and between Ki67 index and the presence of hepatic metastasis (r(s) = 0.48; p = 0.0022). CONCLUSION The contrast-enhanced sonographic enhancement pattern of nonfunctioning pancreatic endocrine tumors has a positive correlation with Ki67 index, which is considered the most reliable independent predictor of the presence of malignancy.

Radiation dose saving through the use of cone-beam CT in hearing-impaired patients

PurposeBionic ear implants provide a solution for deafness. Patients treated with these hearing devices are often children who require close follow-up with frequent functional and radiological examinations; in particular, multislice computed tomography (MSCT). Dental volumetric cone-beam CT (CBCT) has been reported as a reliable technique for acquiring images of the temporal bone while delivering low radiation doses and containing costs. The aim of this study was to assess, in terms of radiation dose and image quality, the possibility of using CBCT as an alternative to MSCT in patients with bionic ear implants.Materials and methodsOne hundred patients (mean age 26 years, range 7–43) with Vibrant SoundBridge implants on the round window underwent follow-up: 85 with CBCT and 15 with MSCT. We measured the average tissue-absorbed doses during both MSCT and CBCT scans. Each scan was focused on the temporal bone with the smallest field of view and a low-dose protocol. In order to estimate image quality, we obtained data about slice thickness, high- and low-contrast resolution, uniformity and noise by using an AAPM CT performance phantom.ResultsAlthough the CBCT images were qualitatively inferior to those of MSCT, they were sufficiently diagnostic to allow evaluation of the position of the implants. The effective dose of MSCT was almost three times higher than that of CBCT.ConclusionsOwing to low radiation dose and sufficient image quality, CBCT could be considered an adequate technique for postoperative imaging and follow-up of patients with bionic ear implants.RiassuntoObiettivoGli impianti bionici all’orecchio rappresentano una soluzione contro la sordità. I pazienti trattati con questi tipi di ausili, spesso bambini, necessitano di un follow-up di esami sia funzionali che radiologici, in particolare mediante tomografia computerizzata multistrato (MSTC). La TC volumetrica dentale a fascio conico (CBCT) è una metodica utile allo studio dell’osso temporale, con il vantaggio di erogare basse dosi di radiazioni ionizzanti e di avere costi di gestione contenuti. Lo scopo dello studio è di valutare la CBCT in termini di dose radiante e di qualità d’immagine: il suo eventuale impiego in alternativa alla MSTC (con il protocollo attualmente utilizzato) comporterebbe infatti una sostanziale riduzione della dose ai pazienti con orecchio bionico.Materiali e metodiSono stati inclusi 100 pazienti ipoacusici (età media 26 anni, range 7–43), trattati mediante protesi Vibrant SoundBridge alla finestra rotonda, 15 studiati in follow-up mediante TC e 85 mediante CBCT, calcolando le dosi medie assorbite per tessuto sia durante esame MSTC che CBCT: ogni studio era focalizzato sull’osso temporale utilizzando il più piccolo campo di vista ed il protocollo a bassa dose radiante. Per la stima della qualità dell’immagine, sono stati ottenuti i valori di spessore di strato, risoluzione ad alto e basso contrasto e uniformità/rumore mediante l’uso di fantoccio AAPM CT performance.RisultatiLe immagini ottenute con la CBCT sono di qualità inferiore rispetto alla MSTC, ma sufficientemente diagnostiche, permettendo di valutare con sicurezza la posizione delle estremità degli impianti acustici. La dose efficace della MSTC è risultata circa tre volte superiore rispetto a quella della CBCT.ConclusioniLa CBCT, grazie alla bassa dose impartita e alla sufficiente qualità delle immagini, può essere considerata tecnica radiologica adeguata per i controlli postoperatori ed il follow-up dei pazienti con orecchio bionico.

Focal liver lesions: sinusoidal phase of CEUS

Ultrasound examination is the first imaging modality for hepatic study in neoplastic and chronic liver diseases. Focal liver lesions frequently cause diagnostic problems in terms of characterization, especially when small and hypoechoic to the rest of the parenchyma. Contrast- enhanced ultrasonography (CEUS) has shown its value in the characterization of focal liver lesions. This study assessed the value of the sinusoidal phase of CEUS with a second-generation contrast agent in the characterization of focal liver lesions to distinguish benign from malignant. Two hundred hepatic lesions with suspicious features at baseline ultrasound were prospectively studied with CEUS. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of the sinusoidal phase in the characterization of benign versus malignant liver lesions were evaluated. Hypoechogenicity of the focal liver lesion, during the sinusoidal phase of CEUS, allowed the diagnosis of malignancy with a sensitivity of 85%, specificity of 88%, positive predictive value of 92%, negative predictive value of 77%, and diagnostic accuracy of 86%. The diagnostic confidence in the diagnosis of malignancy significantly increased, with receiver operating characteristic curve areas from 0.536 for baseline ultrasound to 0.902 for the sinusoidal phase of CEUS.

Evaluation of colonic involvement in endometriosis: double-contrast barium enema vs. magnetic resonance imaging.

BackgroundThe purpose of the study was to compare the accuracy of double-contrast barium enema (DCBE) and magnetic resonance imaging (MRI) in the diagnosis of intestinal endometriosis using the histological examination on resected specimen as comparative standard.MethodsEighty-three consecutive patients with suspected intestinal endometriosis, resected between 2005 and 2007, were prospectively evaluated. All of the women underwent preoperative DCBE and MRI on the same day. We evaluated number, site (rectum, sigmoid, cecum), and size of the lesions. The imaging findings were correlated with those resulting at pathology.ResultsAmong the 65 women who underwent surgery, 50/65 (76.9%) were found to have bowel endometriosis, with 9/50 (18%) patients presenting two lesions; DCBE allowed to detect 50/59 (84.7%) lesions. MRI allowed to detect 42/59 (71.1%) lesions. DCBE showed sensibility, specificity, PPV, NPV, and accuracy of respectively 84.7, 93.7, 98.0, 62.5, and 86.6%, MRI of 71.1, 83.3, 93.3, 46.8, and 74.6%.ConclusionDCBE is more accurate than unenhanced MRI in the diagnosis of bowel endometriosis, and should be preferred in the preoperative management of this disease, since it usually enables a proper surgical planning.

Barium Enema Evaluation of Colonic Involvement in Endometriosis

OBJECTIVE The purpose of our study was to define the role of double-contrast barium enema (DCBE) compared with laparoscopy in the diagnosis and local staging of intestinal endometriosis. MATERIALS AND METHODS A search of our radiology database revealed the cases of 234 women who underwent surgical resection for pelvic endometriosis with associated intestinal surgery for intestinal endometriosis. We retrospectively evaluated all preoperative DCBE images for the presence of bowel endometriosis and the number, site (rectum, sigmoid, cecum), and size of the lesions. The radiographic findings at DCBE were retrospectively correlated with those at surgical pathologic examination. RESULTS DCBE revealed 211 intestinal lesions of bowel endometriosis in 168 (71.8%) of 234 patients with pelvic endometriosis clinically enrolled. Forty (23.8%) of the 168 women had more than one endometriotic bowel nodule (two nodules in 37 cases, three in three cases). Laparoscopy revealed 233 intestinal lesions in 174 (74.3%) of the patients. Fifty-four (31.0%) of 174 women had more than one endometriotic bowel nodule (two nodules in 49 cases, three in five cases). There was 100% correlation between the DCBE and histologic findings as far as site and size of the lesions were concerned. DCBE had a sensitivity of 88.4%, specificity of 93.0%, positive predictive value of 97.5%, negative predictive of 71.0%, and accuracy of 89.5% in the identification of bowel endometriosis. CONCLUSION DCBE is helpful in discerning bowel wall involvement in endometriosis, enabling proper surgical planning. DCBE also appears to have a role in the management of endometriosis.

Contrast-Enhanced Ultrasonography of the Pancreas

Ultrasound is often the first examination performed in patients with suspicion of pancreatic disease. The introduction of contrast-enhanced ultrasonography (CEUS) has led to great developments in the diagnostic capabilities of ultrasound. Dynamic observation of an enhancement allows a highly sensitive evaluation of any perfusion of the abdominal organs. Study of the pancreas is a new and promising application of CEUS, and can be used to characterize pancreatic lesions visible with conventional ultrasonography (US). This article reviews the clinical and surgical applications of CEUS in different pancreatic diseases and in their management.

The diagnostic contribution of CT volumetric rendering techniques in routine practice

Computed tomography (CT) volumetric rendering techniques such as maximum intensity projection (MIP), minimum intensity projection (MinIP), shaded surface display (SSD), volume rendering (VR), and virtual endoscopy (VE) provide added diagnostic capabilities. The diagnostic value of such reconstruction techniques is well documented in literature. These techniques permit the exploration of fine anatomical detail that would be difficult to evaluate using axial reconstructions alone. Although these techniques are now widely available, many radiologists are either unfamiliar with them or do not fully utilize their potential in daily clinical practice. This paper is intended to provide an overview of the most common CT volumetric rendering techniques and their practical use in everyday diagnostics.