Sergio Racchiusa

Stone-Targeted Dual-Energy CT: A New Diagnostic Approach to Urinary Calculosis

OBJECTIVE The objective of our study was to assess a stone-targeted low-dose protocol for the detection and characterization of urinary tract stones using a dual-energy CT scanner. SUBJECTS AND METHODS Thirty-nine patients (20 men, 19 women; age range, 22-87 years; average age, 47 years) with suspected renal colic in which ureteral stones were shown at low-dose unenhanced CT were enrolled in the study. Stone composition could be established in 24 patients, and these patients represent our study population regarding the CT characterization of stones. All examinations were performed with a preliminary low-dose unenhanced CT acquisition of the whole urinary system that was immediately followed by a limited (scanning length, 5 cm) dual-energy acquisition of the region containing the ureteral stone. Stone characterization was assessed using a dual-energy software tool available on the system. Two experienced radiologists who were blinded to the chemical composition of the stones retrospectively reviewed images and analyzed data to determine the composition of the stones. Their results were compared with the biochemical analysis results obtained by stereomicroscopy and infrared spectrometry. RESULTS Based on in vitro-measured data, our combined protocol reduced dose by up to 50% compared with a full dual-energy acquisition; in addition, the calculated radiation doses of our protocol in patients are comparable to those of low-dose single- and dual-energy protocols. In 24 patients, 24 ureteral stones considered to be responsible for symptoms and detected at low-dose unenhanced CT were also shown at dual-energy CT. Correct chemical composition was obtained by dual-energy analysis in all 24 ureteral calculi regarding the characterization of uric acid (n = 3), calcium salt (n = 18), and combined uric acid-calcium salt (n = 3) stones. CONCLUSION The use of dual-energy CT attenuation values made it possible to characterize all ureteral calculi, discriminating uric acid stones from calcium salt stones. The increment in radiation exposure due to contemporary scanning with two tubes at different energy levels can be substantially reduced using a limited stone-targeted dual-energy protocol.

Dual-Source Dual-Energy CT Evaluation of Complex Cystic Renal Masses

OBJECTIVE The purpose of this study was to assess the value of dual-source dual-energy CT in the evaluation of complex cystic renal masses. SUBJECTS AND METHODS Seventy patients underwent contrast-enhanced dual-energy CT that included true unenhanced images acquired in single-energy mode, corticomedullary phase images acquired in dual-energy mode, and nephrographic phase images acquired in single-energy mode. Virtual unenhanced, blended weighted-average, and color-coded iodine overlay images were reconstructed. The acceptance level and image quality of virtual and true unenhanced images were evaluated. Contrast enhancement on both true unenhanced or blended weighted-average images and color-coded iodine overlay images was evaluated with both calculation in regions of interest and use of confidence level scales. Radiation dose parameters were estimated. RESULTS Virtual unenhanced images of 70 lesions (97.2%) and true unenhanced images of 72 lesions (100%) were judged acceptable (p = 0.5). The mean quality score of virtual unenhanced images was 2.0 ± 0.7 and of true unenhanced images was 1.5 ± 0.5 (p < 0.001). Mean contrast enhancement measured on true unenhanced and blended weighted-average images was 45.9 ± 15.9 HU (range, 21-78 HU) and on color-coded iodine overlay images was 47.3 ± 16.8 HU (range, 22-75 HU) with no significant differences. Enhancement was excluded on color-coded iodine overlay images with a significantly (p < 0.03) higher level of confidence than it was on true unenhanced and blended weighted-average images. The mean dose reduction with use of a combined dual- and single-energy dual-phase CT protocol was 29.1% ± 11.9% (p < 0.001). CONCLUSION Dual-source dual-energy CT is a reliable imaging technique in the evaluation of complex cystic renal masses. True unenhanced images can be replaced by virtual unenhanced images with considerable radiation dose reduction. The color-coded iodine overlay technique is a useful tool for both excluding and identifying endocystic enhancement.

Dual-energy CT for detection of endoleaks after endovascular abdominal aneurysm repair: usefulness of colored iodine overlay.

OBJECTIVE The purpose of our study was to evaluate the value of dual-source dual-energy CT with colored iodine overlay for detection of endoleaks after endovascular abdominal aortic aneurysm repair. We also calculated the potential dose reduction by using a dual-energy CT single-phase protocol. SUBJECTS AND METHODS From November 2007 to November 2009, 74 patients underwent CT angiography 2-7 days after endovascular repair during single-energy unenhanced and dual-energy venous phases. By using dual-energy software, the iodine overlay was superimposed on venous phase images with different percentages ranging between 0 (virtual unenhanced images) and 50-75% to show the iodine in an orange color. Two blinded readers evaluated the data for diagnosis of endoleaks during standard unenhanced and venous phase images (session 1, standard of reference) and virtual unenhanced and venous phase images with colored iodine overlay images (session 2). We compared the effective dose radiation of a single-energy biphasic protocol with that of a single-phase dual-energy protocol. The diagnostic accuracy of session 2 was calculated. RESULTS The mean dual-energy effective dose was 7.27 mSv. By using a dual-energy single-phase protocol, we obtained a mean dose reduction of 28% with respect to a single-energy biphasic protocol. The diagnostic accuracy of session 2 was: 100% sensitivity, 100% specificity, 100% negative predictive value, and 100% positive predictive value. Statistically significant differences in the level of confidence for endoleak detection between the two sessions were found by reviewers for scores 3-5. CONCLUSION Dual-energy CT with colored iodine overlay is a useful diagnostic tool in endoleak detection. The use of a dual-energy single-phase study protocol will lower radiation exposure to patients.

Usefulness of contrast-enhanced ultrasonography in the diagnosis of renal pseudotumors

Background: Within the term “pseudotumors” are grouped some renal anatomic variations that may simulate a focal renal lesion at ultrasonography. Our purpose was to assess the accuracy of contrast-enhanced ultrasonography (CEUS) using a second-generation contrast agent in the diagnosis of renal pseudotumors. Methods: We retrospectively retrieved CEUS examinations performed in 24 patients for characterization of suspected renal pseudotumor, in which conventional and power Doppler US study had been unable to confidently exclude a neoplasm. The considered criterion to define the diagnosis of renal pseudotumor was the demonstration of the same perfusion and reperfusion after microbubble breakage in both pseudotumor and surrounding parenchyma during early and late corticomedullary phase. In all patients, multiphase CT or dynamic MRI was available, representing a standard of reference for this study. In cases of CT or MRI diagnosis of renal lesion, final diagnoses were obtained with percutaneous renal biopsy or with surgery. Results: Contrast-enhanced ultrasonography diagnosis was concordant with MR or CT images in all cases. Conclusion: In our experience CEUS shows complete concordance with CT and MRI in the characterization of all 24 pseudotumors considered dubious at conventional and power Doppler US. The appropriate use of CEUS can reduce the need for contrast-enhanced CT or dynamic MRI in this item.

Giant fibrovascular polyp of the esophagus : CT and MR findings

Abstract. We present a case of giant fibrovascular polyp of the esophagus with predominant fat contents. Both computed tomography (CT) and magnetic resonance imaging (MRI) findings of this rare tumor are reported. The employment of CT and MRI in the presurgical evaluation of fibrovascular esophageal polyp is suggested.

Opposed-phase MR imaging of lipid storage myopathy in a case of Chanarin–Dorfman disease

Chanarin–Dorfman disease (CDD) is a rare genetic disorder characterized by ichthyosis, myopathy, central nervous system disturbances, and intracellular lipid storage in muscle fibers, hepatocytes, and granulocytes. We describe skeletal muscle magnetic resonance imaging findings in a case of CDD, outlining the potential role of GE T1-weighted opposed-phase sequence (chemical shift imaging) in the evaluation of lipid storage myopathies.

Role of coronal oblique reconstruction as a complement to CT study of the temporal bone: normal anatomy

Purpose.The purpose of this study was to demonstrate the usefulness of coronal oblique multiplanar reconstruction computed tomography (MPR CT) reformation parallel to the basal turn of the cochlea in the evaluation of the retrotympanum and hypotympanum to complete the standard CT examination of the temporal bone obtained with axial and coronal images.Materials and methods.We studied 30 patients aged 18–79 years for a total of 60 normal petrous pyramids. All examinations were performed on a multislice CT (MSCT) scanner (Sensation 16, Siemens, Erlangen, Germany) with axial volumetric acquisition and completed with reformations of coronal and coronal–oblique images. MSCT scan parameters for axial acquisition were set as follows: 0.75–mm scan collimation, FOV 300 mm, 170 mAs. Axial images were reconstructed at 0.7–mm thickness and with a reconstruction increment of 0.5 mm using a high–resolution bone algorithm.Results.Coronal oblique MPR CT reformations provided additional information with respect to standard CT images in all cases. In particular, they enabled measurement of the craniocaudal and laterolateral diameters of the sinus tympani. In all cases, there was optimal visualisation of the ponticulus and subiculum. Analysis of the pyramidal eminence was improved thanks to its visualisation in profile. Moreover, we obtained an optimal representation of the hypotympanum, which was always exhaustively explored with only one reconstruction. Finally, in all cases, it was possible to identify the facial nerve canal and main vascular structures and to measure the distance between these and the sinus tympani, pyramidal eminence and hypotympanum. The coronal oblique CT reformation was of no advantage in the evaluation of the fossa of the oval window and the niche of the round window.Conclusions.Coronal oblique MPR CT reformation should not be considered an alternative to the standard CT examination, but it can represent a valid integration to provide additional information on particularly crucial districts characterised by frequent involvement of inflammatory and/or expansile disease and because of their difficult endoscopic approach. Moreover, it can represent a meaningful aid to optimise surgical planning thanks to its different perspectives of observation.

Multislice computed tomography demonstration of a coronary-to-pulmonary artery fistula.

MSCT-coronary angiography demonstrated a threevessel CAD; no critical stenosis was apparent, but the images were not conclusive owing to severe vascular calcifications. Moreover, a coronary-to-pulmonary artery fistula was disclosed. The fistula came out (Fig. 1a) frontwards, downwards and rightwards from the proximal segment of the left anterior descending artery (LAD). The fistula then inverted its course and formed two ‘U-shaped’ curves – the former larger and the latter narrower – crossed the LAD itself and reached the left wall of the main pulmonary trunk (Fig. 1b), into which it drained after having become ectasic (Fig. 2).

Role of Hemodynamic Forces in Unruptured Intracranial Aneurysms: An Overview of a Complex Scenario

BACKGROUND An understanding of the natural history of unruptured intracranial aneurysms (IAs) has always played a critical role in presurgical or endovascular planning, to avoid possibly fatal events. Size, shape, morphology, and location are known risk factors for rupture of an aneurysm, but morphologic parameters alone may not be sufficient to perform proper rupture risk stratification. METHODS We performed a systematic PubMed search and focused on hemodynamics forces that may influence aneurysmal initiation, growth, and rupture. RESULTS We included 223 studies describing several hemodynamic parameters related to aneurysm natural history. In these studies, different modalities of aneurysm model creation have been used to evaluate flow and to comprehensively analyze the evolution of IAs. Controversy exists about the correlation between these parameters and initiation, growth, rupture risk, or stabilization of the aneurysmal sac. Recent findings have also shown the importance of flow patterns in this process and the relationship between unruptured IA geometry and hemodynamic parameters. CONCLUSIONS The role of hemodynamic forces in evaluation of the natural history of unruptured IAs presents is inherently complex and is still not completely understood. In this complex scenario, although several attempts have been described in the literature, a proper risk rupture stratification and treatment strategy selection based on hemodynamic forces has not yet been created. Further efforts should be made to accomplish this important goal.

Peritoneal inclusion cysts in patients affected by Crohn's disease: magnetic resonance enterography findings in a case series

Peritoneal inclusion cystarises when fluid produced by ovary is trapped within peritoneal adhesions. In this article, we describe a case series of patients affected by Crohns disease, undergoing to magnetic resonance enterography, in whom it was possible not only to monitor the pathological findings of small bowel but also to primarily diagnose the presence of peritoneal inclusion cysts. The current knowledge of peritoneal inclusion cyst concomitant to Crohns disease is still limited, often leading radiologists to misdiagnose it.