Single-phase dual-energy CT urography in the evaluation of haematuria

AIM

To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic-excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan.

MATERIALS AND METHODS

Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic-excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated.

RESULTS

The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%.

CONCLUSION

Single-phase DECT urography with synchronous nephrographic-excretory phase enhancement represents an accurate "all-in-one'' approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol.

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.

Hepatic artery aneurysm, an unusual cause of obstructive jaundice: MR cholangiography findings

Hepatic artery aneurysms are rare vascular lesions, often with a nonspecific clinical presentation, and difficult to diagnose before rupture. We report the case of a patient with obstructive jaundice caused by a compression on the right biliary duct by a right hepatic artery aneurysm in which the diagnosis was suggested by magnetic resonance cholangiography and confirmed by Doppler sonography and preoperative digital subtraction angiography.

Computed tomography features of liparitosis: a pneumoconiosis due to amorphous silica

The purpose of this study was to describe the radiological features of pleural, parenchymal and mediastinal damage due to occupational inhalation of pumice. In total, 31 workers were evaluated for annual follow-up. Spiral computed tomography (CT) was obtained in the three patients with evident parenchymal abnormalities at chest radiograph. High-resolution computed tomography (HRCT) was performed in the remaining 28 subjects with no radiographical evidence of pleuropulmonary damage or evidence of pleural plaques, in order to exclude parenchymal involvement. Pumice samples were analysed by radiograph diffraction and scanning electron microscopy. Spiral CT showed parahilar conglomerate masses containing fine reticular calcifications in three of 31 (9.7%) patients. HRCT showed several bilateral pleural plaques, without any parenchymal lesion in eight of 28 (28.6%) cases. Statistical analysis indicated correlation between CT findings and pulmonary function, as well as exposure to pumice. The analysis of pumice excluded the presence of asbestos. The findings from this study suggest that pleural plaque may be the only sign of disease in patients with a history of pumice inhalation. However, conglomerate parahilar masses are probably due to exposure to massive amounts of heated pumice, and seem to have different pathogenesis and histopathological characteristics to silicosis.

Unusual pleural involvement after exposure to amorphous silicates (Liparitosis): report of two cases

Liparitosis is a rare pneumoconiosis determined by inhalation of pumice, an amorphous complex silicate extracted in the quarries of Lipari (Aeolian Archipelago, Italy). We describe two cases of subjects occupationally exposed to pumice dust in which high-resolution computed tomography (HRCT) revealed the presence of pleural lesions without parenchymal involvement.

Contrast-enhanced power Doppler US in the diagnosis of renal pseudotumors

The term "pseudotumor" is used to refer to several anatomic variants that can simulate a renal mass, the most frequent of which are hypertrophied column of Bertin, persistence of fetal lobation, and the dromedary or splenic hump. We describe the findings of power Doppler US after the ultrasound contrast agent (Levovist, Schering, Berlin, Germany) administration in 4 patients with a renal focal lesion in whom gray-scale and baseline power Doppler US was not able to certainly differentiate pseudotumor from neoplasm.

Ossifying lipoma of the parapharyngeal space: CT and MRI findings

Ossifying lipomas independent of bone tissue are very rare. A literature review revealed that only few cases of ossifying lipoma independent of bone tissue have been reported. None of the cases have been reported in the international radiology literature. In addition, there are no reports concerning the MRI features of this entity. We describe CT and MRI findings in a case of ossifying lipoma of the parapharyngeal space.

MR white lung sign: incidence and significance in pulmonary consolidations

PURPOSE

The presence of a pulmonary consolidation with a signal intensity comparable with that of the static fluid on heavily T2-weighted MR images has been named the "MR white lung sign." This sign has been described in mucinous bronchioloalveolar carcinoma (BAC). Our purpose was to establish the frequency and significance of this sign in pulmonary consolidations of varied causes.

METHOD

In this prospective study, 83 patients with pulmonary consolidation underwent MR examination between January and December 1999. Segmental or lobar consolidations were due to pneumonia without central obstruction (n = 22), pneumonitis with central obstruction (n = 21), cicatricial atelectasis (n = 8), passive atelectasis (n = 10), radiation pneumonitis (n = 8), mucinous BAC (n = 5), infarction (n = 3), bronchiolitis obliterans organizing pneumonia (n = 3), nonmucinous BAC (n = 2), and lymphoma (n = 1). The MR white lung sign was considered present when the signal intensity of a pulmonary consolidation was comparable with that of the static fluid on heavily T2-weighted images obtained with MR hydrography sequences. Interobserver agreement, sensitivity, and specificity of the white lung sign in diagnosing mucinous BAC were calculated.

RESULTS

The MR white lung sign was present in 7 (8%) of 83 consolidations, including 5 (100%) of 5 cases of mucinous BAC and 2 (10%) of 21 cases of obstructive pneumonitis. The frequency of the white lung sign was 100% in mucinous BAC and 2.6% in consolidations due to other causes. The difference was statistically significant (p < 0.05).

CONCLUSION

The white lung sign is an uncommon finding in pulmonary consolidations evaluated with heavily T2-weighted sequences. However, the sign is characteristic of mucinous BAC and adds specificity to the radiologic diagnosis.

Usefulness of power Doppler and contrast-enhanced sonography in the differentiation of hyperechoic renal masses

BACKGROUND

In a prospective study, we compared power Doppler with and without contrast medium in the depiction of vascularity for the characterization of hyperechoic renal lesions.

METHODS

Forty-one hyperechoic renal expansive lesions (29 benign, 12 malignant) in 32 patients were studied with power-Doppler ultrasonography before and after administration of an echo-enhancing agent (Levovist Schering AG, Berlin, Germany). Vascular architecture of the lesions was categorized into five different patterns.

RESULTS

Power Doppler ultrasonography showed vascular structures in 25 lesions. The study enhanced with Levovist showed vascularity in eight of 16 lesions not seen on the unenhanced study. The characterization of vascular patterns with unenhanced power Doppler ultrasonography improved diagnostic accuracy compared with gray-scale ultrasonography (59% vs. 32%). The combination of B mode and power Doppler produced even greater diagnostic accuracy (78%), independent of the administration of echo-enhancing agent. Levovist administration was useful in the differential diagnosis between pseudotumor and neoplasm.

CONCLUSION

The use of sonographic contrast agent did not increase the diagnostic accuracy of power Doppler in the differential diagnosis of hyperechoic renal lesions but was advantageous for the characterization of suspected pseudomasses.

Intrahepatic portal vein aneurysm: three-dimensional power Doppler demonstration in four cases

We describe four cases of portal vein aneurysm that were studied with ultrasonography, color Doppler, computed tomography, and magnetic resonance imaging as well as three-dimensional power Doppler. Three-dimensional ultrasonography showed the portal aneurysm and its relationship to its portal branches in all patients and showed the portosystemic communication in three. In all cases, computed tomography or magnetic resonance imaging confirmed the three-dimensional ultrasonographic findings.

Perineural spread in a case of sinonasal sarcoidosis: case report

We report a case of sinonasal sarcoidosis with perineural spread along the trigeminal and vidian nerves in which primarily MR imaging but also CT allowed excellent visualization of this infiltration.

Gallbladder duplication: MR cholangiography demonstration

Gallbladder duplication is a rare anatomic malformation. We present a case of gallbladder duplication in a patient who underwent laparoscopic cholecystectomy in which breath-hold magnetic resonance cholangiography showed the biliary anomaly, allowing a correct preoperative differentiation of the specific type of duplication.

Potential role of colour-Doppler cystosonography with echocontrast in the screening and follow-up of vesicoureteral reflux

Primary vesicoureteral reflux is a predisposing factor for urinary tract infections in children. The first-choice technique for the diagnosis of vesicoureteral reflux is voiding cystourethrography, followed by cystoscintigraphy; cystoscintigraphy, however, has the advantage of only minor irradiation of the patient, but it does not allow the morphological evaluation of bladder and vesicoureteral reflux grading. Colour-Doppler cystosonography with echocontrast is a recently introduced method for imaging vesicoureteral reflux. The aim of our study is to evaluate the role of colour-Doppler cystosonography with echocontrast in the diagnosis of vesicoureteral reflux. Twenty children (11M, 9F) aged between 0.4 and 4.9 y underwent colour-Doppler cystosonography using a diluted solution of Levovist (Schering, Germany), after filling up the bladder with saline. In all patients, vesicoureteral reflux diagnosis and grading had been performed previously by voiding cystourethrography within 5 d from ultrasonography. Our data showed high accuracy in the detection of medium to severe vesicoureteral reflux (grades III-V), confirmed by radiological features in 9/9 patients. Conversely, in the 11 patients with mild vesicoureteral reflux (grades I-II), this technique showed extremely low sensitivity, allowing diagnosis in only four cases.

CONCLUSIONS

Colour-Doppler cystosonography, because of the absence of ionizing radiations, has great advantages, particularly in patients needing prolonged monitoring. Despite experiences reported in the literature, this technique has a role in the diagnosis of vesicoureteral reflux. Our group chooses colour-Doppler cystosonography for the follow-up of medium-severe grade vesicoureteral reflux already diagnosed by radiology and/or scintigraphy. Cystoscintigraphy is employed only to confirm cases resulting negative at ultrasonography.

Hepatobronchial fistula due to transphrenic migration of hepatic echinococcosis: MR demonstration

We present an uncommon case of hepatic hydatidosis, complicated by transphrenic migration of the cyst, in which the use of magnetic resonance performed with ultrafast, breath-hold, heavily T2-weighted sequences (HASTE) demonstrated a bronchial fistula.

[Doppler power with contrast media in the characterization of renal masses]

PURPOSE

To report the results of a prospective study investigating the potentials of contrast-enhanced power Doppler in the diagnosis of expansive renal lesions.

MATERIAL AND METHODS

From 1997 to October 30, 1999, we studied 59 expansive renal lesions (28 malignant, 31 benign) in 48 patients (mean age 55 years, range 10-79) with power Doppler US before and after the administration of an echo-enhancing agent (Levovist, Schering AG, Berlin, Germany). We identified 5 patterns of vascular architecture of the lesions, both before and after contrast agent administration, following the classification by Jinzaki e Coll.

RESULTS AND DISCUSSION

Power Doppler US showed vascular structures in 34 patients. The administration of Levovist revealed vessels in 12/25 lesions which had none at baseline studies and in 6 cases vascularity was particularly evident. Color signals were enhanced in all the 34 vascularized lesions, which allowed better definition of vascular patterns. The characterization of vascular patterns with baseline power Doppler US helped improve diagnostic accuracy compared to gray-scale US (58% versus 32%) for hyperechoic lesions, complex cysts and pseudomasses. Independent of contrast agent administration, the integration of gray-scale and power Doppler modes increased diagnostic accuracy even further (76% correct diagnoses).

CONCLUSIONS

In our series, the US contrast agent did not increase the diagnostic accuracy of power Doppler in the differential diagnosis of hyperechoic renal lesions; conversely, Levovist can be advantageous for the characterization of suspected pseudomasses and complex cysts.

Diagnostic pitfalls of breath-hold MR urography in obstructive uropathy

Breath-hold MR urography (MRU) is being used with increasing frequency to evaluate urinary tract pathology. Although multiple studies have documented the accuracy of breath-hold MRU in the evaluation of obstructive uropathy, pitfalls associated with this technique may result in diagnostic errors. This essay illustrates both technical and interpretive pitfalls of MRU and suggests strategies for their recognition and avoidance.

[The role of computed tomography after functional surgery on the paranasal sinuses. Normal findings and an assessment of the surgical failures]

INTRODUCTION

Functional endoscopic sinus surgery has become the technique of choice to treat benign or inflammatory diseases of paranasal sinuses resistant to medical therapy. The goal of this type of surgery is to open the obstructed sinus ostia and restore normal aeration and mucociliary clearance. Messerklinger's is the most widely used technique.

PURPOSE

We investigated the role of CT after functional endoscopic sinus surgery and describe CT findings of postoperative anatomical changes together with frequent complications and surgical failures.

METHODS AND MATERIALS

Twenty-seven patients with relapsing symptoms were examined with CT of paranasal sinuses 8-32 weeks after functional endoscopic sinus surgery. In all cases both preoperative CT and surgical reports were available: CT and surgical results were compared.

RESULTS

In 21/27 patients nasosinusal changes were demonstrated with CT. Recurrent disease secondary to inflammation and/or fibrosis was observed in 14 cases. Residual disease was seen in 5 patients. A major orbital complication was found in 1 patient with diplopia. One patient exhibited a large interruption of cribriform plate with CSF fistula.

CONCLUSION

CT permitted an accurate assessment of extension and results of functional endoscopic sinus surgery. CT is indicated in the postoperative study of the patients who a) present symptoms of cerebral and ocular complications (early after functional endoscopic sinus surgery); and b) do not respond to medical treatments 8-32 weeks after unsuccessful functional endoscopic sinus surgery. In these patients CT can demonstrate recurrent and/or residual nasosinusal disease and bony defects unintentionally caused by the surgeon during the procedure.

Giant fibrovascular polyp of the esophagus: CT and MR findings

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.

[Use of oral superparamagnetic contrast media in cholangiopancreatography with TSE single-shot magnetic resonance]

PURPOSE

To investigate the yield of an oral superparamagnetic contrast agent (Lumirem) in turbo spin echo (TSE) single-shot MR cholangiopancreatography (MRCP) in patients candidate to laparoscopic cholecystectomy.

MATERIAL AND METHODS

Thirty patients (mean age: 52.2 years) scheduled for laparoscopic cholecystectomy underwent MRCP with TSE single-shot sequences. To cover the biliary tree, thick-section TSE images were acquired according to the cross-sectional location of the biliary tract. Six 50-mm images progressively rotated by 30 degrees each were acquired during breath-holds. The precontrast images were obtained before the negative oral contrast agent was administered. The postcontrast images were acquired 10 minutes after oral contrast agent administration. Two observers made a qualitative evaluation on all images: the contrast enhancement was assessed comparing the pre- and postcontrast images of each examination on the basis of signal intensity in the stomach and duodenum, giving a score on a graduate scale. The greater yield of postcontrast images was validated by statistical analysis. The actual diagnostic improvement obtained with postcontrast images was validated for every single case.

RESULTS AND CONCLUSIONS

The greater yield of postcontrast images was statistically significant in the common bile and cystic ducts, but not in the gallbladder and Wirsung duct. Better images were obtained in 22/30 patients. The actual diagnostic improvement in the visualization of the common bile and cystic ducts was statistically significant in 7/30 patients. To conclude, administering an oral negative contrast agent improved image quality and the diagnostic yield. The agent was well tolerated and safe and we suggest its use in TSE single-shot MRCP of the patients candidate to laparoscopic cholecystectomy.

[Computerized tomography findings in benign diseases of the sphenoid sinus]

INTRODUCTION

Benign diseases of the sphenoid sinus can be classified as intrinsic, originating from the mucosa and sinus bone walls, and extrinsic, arising from adjacent structures. We analyze the CT features of both intrinsic and extrinsic benign sphenoid conditions and their diagnostic role and impact on treatment planning.

MATERIAL AND METHODS

We reviewed the CT scans of 75 patients with benign sphenoid sinus conditions from our 1993-96 series. The conditions were diagnosed at histology of the surgical specimen or from clinical findings and patient's history. Both axial scans, parallel to the orbitomeatal line, and coronal scans, perpendicular to the hard palate, were always acquired. The matrix was 512 x 512 and the FOV was appropriate. The different diseases were diagnosed based on the CT features of normal sinus bone walls or, conversely, wall thickening/thinning, focal erosions or bone destruction. The density of intra- and extrasinusal tissue and its contrast enhancement, intratissutal calcifications or bone fragments and changes in the sphenoethmoid recess were also studied.

RESULTS

Sinus bone walls were normal in 41/75 cases, focal/diffuse thinning was found in 12, focal interruption in 7 and thickening in 10. Intra- and perisinusal tissue with soft-tissue density was detected in 66/71 cases, with high density in 4 and low density in 1 case. Contrast enhancement of the pathologic tissue was found in 15 cases. Sphenoethmoid obliteration was demonstrated in 29 cases, with enlargement in 5 and reduction in 5.

DISCUSSION

Benign diseases of the sphenoid sinus are an uncommon finding. They are mainly due to chronic or recurrent inflammatory diseases, frequently associated with pansinusal involvement. Sphenoid sinus involvement can also be found in pathologic conditions originating from adjacent structures. We conclude that the accurate study of the intra- and extrasinusal soft tissue and bone walls permits to hypothesize the nature of a benign pathologic process, which has an impact on treatment planning. CT can be considered the technique of choice in the study of the sphenoid region.