R. Pozzi Mucelli

Acoustic Radiation Force Impulse (ARFI) technique in ultrasound with Virtual Touch tissue quantification of the upper abdomen

Purpose. Virtual Touch tissue quantification is an implementation of ultrasound (US) Acoustic Radiation Force Impulse (ARFI) imaging that provides numerical measurements (wave-velocity values) of tissue stiffness. The aim of this study was to define the normal values of shear-wave speed for the healthy liver, gallbladder, pancreas, spleen and kidneys. Materials and methods. Thirty-five young healthy volunteers underwent Virtual Touch tissue quantification after having signed an informed consent form. All upper abdominal organs were examined by two independent operators. A phantom fluid model was also evaluated. All mean wave-velocity values were analysed and compared. Results. One hundred and forty measurements of liver, pancreas, spleen and kidneys, and 70 measurements of the gallbladder lumen were performed. Twenty measurements on the phantom were also performed. Comparing all measurements separately made by each operator in different parts of the organs, no statistically significant differences were observed. A “XXXX/0” value was always obtained from all measurements performed on the gallbladder lumen and on the phantom fluid model. Liver, pancreas, spleen and kidney mean values were 1.59 m/s, 1.40 m/s, 2.44 m/s and 2.24 m/s, respectively. Conclusions. Virtual Touch tissue quantification is a new, promising implementation of the US ARFI technique, which provides numerical measurements of tissue stiffness. The mean shear-wave speed is lower in the pancreatic parenchyma than in the liver and kidney, whereas the spleen is characterised by the highest mean value. In Riassunto Obiettivo. Il Virtual Touch tissue quantification è una applicazione quantitativa della tecnica ecografica Acoustic Radiation Force Impulse (ARFI) che fornisce valori numerici dell’elasticità dei tessuti. Lo scopo dello studio è definire i valori di normalità di fegato, colecisti, pancreas, milza e reni. Materiali e metodi. Sono stati studiati 35 giovani volontari sani. Un consenso informato è stato ottenuto prima dell’esame. Gli organi addominali superiori sono stati studiati da due operatori indipendenti. È stato inoltre studiato un phantom contenente acqua. Tutti i valori medi di velocità di propagazione dell’onda sono stati analizzati e confrontati. Risultati. Sono state effettuate 140 misurazioni su fegato, pancreas, milza e reni, 70 nel lume della colecisti e 20 nel phantom. Confrontando tutte le misurazioni eseguite da ciascun operatore in differenti parti dei vari organi addominali, non sono risultate differenze statisticamente significative. Tutte le misurazioni effettuate su colecisti e phantom hanno fornito un valore definito “XXXX/0”. Fegato, pancreas, milza e reni avevano valori medi rispettivamente di 1,59 m/s, 1,40 m/s, 2,44 m/s e 2,24 m/s. Conclusioni. Il Virtual Touch tissue quantification è una promettente applicazione della tecnica ecografica ARFI, che consente una valutazione espressa in numeri della durezza dei tessuti. Il valore medio della velocità di propagazione dell’onda nel parenchima pancreatico è inferiore rispetto a quella misurata nel fegato e nei reni, mentre la milza è caratterizzata da valore medio più alto. Nei fluidi semplici, come l’acqua, viene sempre riscontrato ABDOMINAL RADIOLOGY RADIOLOGIA ADDOMINALE Radiol med (2010) 115:889–897 DOI 10.1007/s11547-010-0504-5 Acoustic Radiation Force Impulse (ARFI) technique in ultrasound with Virtual Touch tissue quantification of the upper abdomen Tecnica Acoustic Radiation Force Impulse (ARFI) nello studio ecografico con Virtual Touch tissue quantification dell’addome superiore A. Gallotti • M. D’Onofrio • R. Pozzi Mucelli Istituto di Radiologia, Policlinico G. B. Rossi, Università di Verona, Piazzale L. A. Scuro 10, 37134 Verona, Italy Correspondence to: M. D’Onofrio, Tel.: +39-045-8124301, Fax: +39-045-8027490, e-mail: mirko.donofrio@univr.it Received: 19 May 2009 / Accepted: 28 July 2009 / Published online: 15 January 2010

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.

Acoustic Radiation Force Impulse (ARFI) ultrasound imaging of solid focal liver lesions

OBJECTIVE The aim of this paper was to evaluate the application of ARFI ultrasound imaging and its potential value for characterizing focal solid liver lesions. MATERIALS AND METHODS In this multicentric prospective study, over a total non-consecutive period of four months, all patients underwent ARFI US examination. Two independent operators performed 5 measurements per each lesion and 2 measurements in the surrounding liver. According to the definitive diagnosis, a mean velocity value and standard deviations were obtained in each type of focal solid lesion, compared by using t-test, and the inter-operator evaluation was performed by using the Students t-test. A comparison between the total mean values of each type of lesion and the mean value of the parenchyma was performed. RESULTS 40 lesions were evaluated and a total of 400 measurements were obtained. The lesions were: 6/40(15%) hepatocellular carcinomas, 7/40(17.5%) hemangiomas, 5/40(12.5%) adenomas, 9/40(22.5%) metastases and 13/40(32.5%) focal nodular hyperplasias. The total mean values obtained were: 2.17 m/s in HCCs, 2.30 m/s in hemangiomas, 1.25 m/s in adenomas, 2.87 m/s in metastases and 2.75 m/s in FNHs. The inter-operator evaluation resulted non-statistically different (p>0.05). A significant difference (p<0.05) was always found by comparing adenomas to the other lesions. 160 measurements were obtained in the surrounding parenchyma, with a no significant difference between values measured in adenomas and in the surrounding liver. CONCLUSIONS ARFI technology with Virtual Touch tissue quantification could non-invasively provide significant complementary information regarding the tissue stiffness, useful for the differential diagnosis of focal solid liver lesions.

Branch duct IPMTs: value of cross-sectional imaging in the assessment of biological behavior and follow-up.

Branch duct intraductal papillary mucinous tumors (IPMTs) are increasingly being described and represent a challenge for the physician. Recent imaging modalities, especially computed tomography and magnetic resonance, allow for a correct diagnosis, but IPMTs can manifest with different degrees of cellular atypia so it is very important to be able to establish the biological behavior of the lesion. Sixty-five patients were included in this study: 29 of them underwent surgery, and the other 36 were followed with cross-sectional imaging. Among patients who underwent surgery, 11 had benign lesions and 18 had malignant lesions. Overall sensitivity, specificity, and accuracy in the diagnosis of malignancy for all the cross-sectional imaging techniques were 61%, 81%, and 69%, respectively. Among patients who were followed and had a magnetic resonance cholangiopancreatographic diagnosis of branch duct IPMT with imaging features indicative of benignity, only two showed modifications over the follow-up period. Even considering some important biases (small number of patients and relatively short follow-up), interesting conclusions can be drawn: the imaging diagnosis of malignancy can be trusted, whereas that of benignity cannot be relied upon, but if the signs of malignancy are absent, the slow growth of the lesions justifies watchful follow-up in the correct clinical setting.

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.

Autoimmune pancreatitis: imaging findings on contrast-enhanced MR, MRCP and dynamic secretin-enhanced MRCP.

PurposeThis study retrospectively determined magnetic resonance (MR), MR cholangiopancreatography (MRCP) and secretin-MRCP findings in patients with autoimmune pancreatitis (AIP).Materials and methodsThe MR examinations of 28 patients with histopathologically proven AIP were reviewed. In 14 cases, secretin-enhanced MRCP was performed. The observers evaluated pancreatic parenchymal enlargement, signal intensity abnormalities, enhancement, vascular involvement, bile-duct diameter and main pancreatic duct (MPD) narrowing (diffuse/focal/segmental). After secretin administration, the presence of the “duct-penetrating” sign was evaluated.ResultsMR imaging showed diffuse pancreatic enlargement in 8/28(29%) cases, focal pancreatic enlargement in 16/28 (57%) cases and no enlargement in 4/28 (14%) cases. The alteration of pancreatic signal intensity was diffuse in 8/28 (29%) cases (eight diffuse AIP) and focal in 20/28 (71%) cases (20 focal AIP). Delayed pancreatic enhancement was present in all AIP, with peripheral rim of enhancement in 8/28 (29%) AIP (1/8 diffuse, 7/20 focal); vascular encasement was present in 7/28 (25%) AIP (1/8 diffuse, 6/20 focal); distal common bile duct narrowing was present in 12/28(43%) AIP (5/8 diffuse, 7/20 focal). MRCP showed MPD narrowing in 17/28 (61%) AIP (4/8 diffuse, 15/20 focal), MPD dilation in 8/28(29%) AIP (3/8 diffuse, 5/20 focal) and normal MPD in1/8 diffuse AIP. Secretin-MRCP showed the duct-penetrating sign in 6/14(43%) AIP (one diffuse AIP with MPD segmental narrowing, five focal AIP with MPD focal narrowing), demonstrating integrity of the MPD.ConclusionsDelayed enhancement and MPD stenosis are suggestive for AIP on MR and MRCP imaging. Secretin-enhanced MRCP is a problem-solving tool in the differential diagnosis between focal AIP and ductal adenocarcinoma.RiassuntoObiettivoScopo di questo lavoro è stato valutare i rilievi di pancreatite autoimmune (AIP) nella revisione retrospettiva delle immagini di risonanza magnetica (RM), colangiopancreatografia-RM (CPRM) e CPRM con secretina.Materiali e metodiÈ stata valutata l’indagine RM di 28 pazienti con diagnosi patologica di AIP; in 14 casi è stato espletato l’esame CPRM con somministrazione di secretina. Le immagini sono state analizzate considerando i seguenti parametri: volume del pancreas, alterazioni dell’intensità di segnale del parenchima, impregnazione del pancreas, coinvolgimento vascolare, calibro delle vie biliari e restringimento (diffuso/focale/segmentale) del dotto pancreatico principale (DPP). Dopo somministrazione di secretina, è stata verificata la presenza del segno del “dotto penetrante”.RisultatiL’esame RM ha evidenziato un incremento dimensionale diffuso del pancreas in 8/28 (29%) casi, un ingrandimento di una parte del pancreas - focale - in 16/28 (57%) casi e pancreas di regolare dimensione in 4/28 (14%) casi. L’alterazione dell’intensità di segnale del pancreas era diffusa in 8/28 (29%) casi (8 AIP di tipo diffuso) e focale in 20/28 (71%) casi (20 AIP di tipo focale). Impregnazione pancreatica tardiva con “cercine” periferico iperintenso si è rilevata in 8/28 (29%) AIP (1/8 AIP di tipo diffuso, 7/20 AIP di tipo focale); “encasement” vascolare è stato dimostrato in 7/28 (25%) AIP (1/8 AIP di tipo diffuso, 6/20 AIP di tipo focale); restringimento del dotto biliare comune è stato rilevato in 12/28 (43%) AIP (5/8 AIP di tipo diffuso, 7/20 AIP di tipo focale). L’esame CPRM ha mostrato restringimento del DPP in 17/28 (61%) AIP (4/8 AIP di tipo diffuso, 15/20 AIP di tipo focale), dilatazione del DPP in 8/28 (29%) AIP (3/8 AIP di tipo diffuso, 5/20 AIP di tipo focale), e DPP normale in 1 AIP di tipo diffuso. L’esame CPRM con secretina ha fatto rilevare il segno del “dotto penetrante” in 6/14 (43%) AIP (1 caso di AIP diffusa con restringimento segmentale del DPP, 5 casi di AIP focale con restringimento focale del DPP) dimostrano l’integrità del DPP.ConclusioniAll’indagine RM e CPRM, il pattern di impregnazione tardivo e l’assotigliamento del DPP sono reperti suggestivi di AIP. La somministrazione di secretina durante l’esame CPRM è uno strumento utile nella diagnosi differenziale tra AIP di tipo focale e adenocarcinoma duttale.

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.

Utility of second-look ultrasound in the management of incidental enhancing lesions detected by breast MR imaging

PurposeTo assess the utility of second-look ultrasound (US) for identifying and characterising incidental enhancing lesions detected by breast magnetic resonance imaging (MRI).Materials and methodsFrom among 655 consecutive breast MRI studies, 62 lesions (MRI visible, nonpalpable, occult at first-look US and mammography) were recommended for second-look US. MRI enhancement of lesions was mass-like in 59 cases (95%) and non-mass-like in three (5%). Forty-two lesions (68%) were ≤10 mm; only three lesions (5%) were >20 mm. Of all lesions, the Breast Imaging Reporting and Data System (BI-RADS) MRI category was highly suggestive of malignancy in six cases (10%), suspicious abnormality in 33 (53%) and probably benign in 23 (37%). The correlation between MRI lesion appearance, lesion size, histopathology findings and detection rate at second-look US were analysed. The reference standard was histopathology and/or follow-up (range 18–24 months). Statistical analysis was performed with the Fisher exact test.ResultsSecond-look US identified 44 out of 62 (71%) lesions depicted at MRI. The detection rate at second-look US was higher for mass-like MRI lesions (75%) than nonmass-like lesions (0%), for lesion size >10mm (90%) and for BI-RADS 4 lesions (88%). Second-look US-guided biopsy detected 12 out of 17 (71%) malignant lesions. There was no correlation between the likelihood of carcinoma and the presence of a sonographic correlate.ConclusionsSecond-look US is a reliable problemsolving tool in identifying and characterising most incidental MRI findings. It contributes to accurately selecting the cases in which MRI-guided biopsy is required.RiassuntoObiettivoLo scopo del lavoro è stato verificare l’utilità del second look ecografico nella identificazione e nella tipizzazione delle lesioni incidentali alla risonanza magnetica (RM) mammaria.Materiali e metodiÈ stata effettuata un’analisi retrospettiva di 62 lesioni identificate incidentalmente dalla RM, non palpabili e occulte alla mammografia ed ecografia espletate prima della RM. L’impregnazione delle lesioni era tipo massa in 59 casi (95%) e non massa in 3 casi (5%). Quarantadue lesioni (68%) erano ≤10 mm; solo 3 lesioni (5%) erano >20 mm. Il grado di sospetto RM era alla classificazione breast imaging reporting and data system (BI-RADS) 5 in 6 casi (10%), BI-RADS 4 in 33 casi (53%), BI-RADS 3 in 23 casi (37%). Le lesioni RM con corrispettivo reperto al second look ecografico sono state analizzate riguardo: aspetto RM, dimensioni, sospetto radiologico, diagnosi istologica. Il gold standard è stato l’esame patologico o il follow-up clinico e strumentale a 24 mesi. I risultati sono stati analizzati con il test statistico di Fisher (significatività: p<0,05).RisultatiIl second look ecografico ha identificato 44/62 (71%) lesioni incidentali alla RM mammaria. Il numero di lesioni identificate con il second-look è stato superiore in caso di impregnazione di tipo massa (75%), lesioni con dimensioni >10 mm (90%) e con BI-RADS 4 (88%). Dodici/44 (27%) lesioni identificate dal second look ecografico erano maligne e 5/18 (27%) lesioni prive di traduzione ecografica erano maligne. Il prelievo guidato dal second look ecografico ha caratterizato 12/17 (71%) lesioni maligne.ConclusioniIl second look ecografico è una valida metodica nel management delle lesioni identificate incidentalmente dalla RM mammaria in quanto consente l’identificazione e la caratterizzazione della maggioranza di esse e l’accurata selezione di quelle da avviare a procedure RM-guidate.

Acoustic radiation force impulse (ARFI) ultrasound imaging of pancreatic cystic lesions

PURPOSE To evaluate the ARFI ultrasound imaging with Virtual Touch tissue quantification in studying pancreatic cystic lesions, compared with phantom fluid models. MATERIALS AND METHODS Different phantom fluids at different viscosity or density (water, iodinate contrast agent, and oil) were evaluated by two independent operators. From September to December 2008, 23 pancreatic cystic lesions were prospectively studied. All lesions were pathologically confirmed. RESULTS Non-numerical values on water and numerical values on other phantoms were obtained. Inter-observer evaluation revealed a perfect correlation (rs=1.00; p<0.0001) between all measurements achieved by both operators per each balloon and fluid. Among the pancreatic cystic lesions, 14 mucinous cystadenomas, 4 pseudocysts, 3 intraductal papillary-mucinous neoplasms and 2 serous cystadenomas were studied. The values obtained ranged from XXXX/0-4,85 m/s in mucinous cystadenomas, from XXXX/0-3,11 m/s in pseudocysts, from XXXX/0-4,57 m/s in intraductal papillary-mucinous neoplasms. In serous cystadenomas all values measured were XXXX/0m/s. Diagnostic accuracy in benign and non-benign differentiation of pancreatic cystic lesions was 78%. CONCLUSIONS Virtual Touch tissue quantification can be applied in the analysis of fluids and is potentially able to differentiate more complex (mucinous) from simple (serous) content in studying pancreatic cystic lesions.