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.

Dual-energy computed tomography (DECT) in renal masses: nonlinear versus linear blending

RATIONAL AND OBJECTIVES

To investigate whether a nonlinear-blending algorithm improves tumor conspicuity and image quality in the evaluation of renal masses at dual-energy computed tomography (DECT) during nephrographic phase of enhancement.

MATERIALS AND METHODS

The Institutional Review Board approved this retrospective study from archival material from patients consenting to the use of medical records for research purposes. A retrospective review of contrast-enhanced abdominal DECT scans in 45 patients (mean age, 59.5 years; range, 24-84 years) was performed. DECT data were reconstructed using nonlinear and linear blending. A region of interest was located within tumors and adjacent normal parenchyma; attenuation differences and contrast-to-noise ratios (CNRs) were calculated for renal masses on nonlinear- and linear-blended images. The two datasets were subjectively compared in terms of tumor detection and image quality. An exact Wilcoxon's matched pairs signed rank and marginal homogeneity tests were used to test whether differences in attenuation, CNR, and subjective assessment were greater using nonlinear blending.

RESULTS

The mean difference in attenuation for renal masses and adjacent portion of renal parenchyma was 138.4 Hounsfield units ± 28.9 SD using nonlinear blending, and 121.6 HU ± 18.0 SD using linear blending (P < .001). Mean CNR was 12.6 ± 2.5 SD using nonlinear blending, and 9.6 ± 2.2 SD using 0.3 linear-blended (P < .001). No significant difference in tumor detection was observed between the two algorithms. Image quality was significantly better (P < .001) using nonlinear blending.

CONCLUSION

Compared with standard linear blending, nonlinear-blending algorithm improves tumor conspicuity and image quality in renal masses at DECT evaluation during nephrographic phase of enhancement.

Guide to magnetic resonance in Crohn's disease: from common findings to the more rare complicances

Considering that multiple imaging examinations are often necessary for monitoring Crohn's disease (CD) activity and severity in order to guide and monitor appropriate treatment, the ideal imaging test would be reproducible, well tolerated by patients, and free of ionizing radiation. For these reasons recent studies have highlighted the role of a magnetic resonance imaging (MRI) technique optimized for small bowel imaging in the evaluation of small bowel disorders. In this regard there are two main methodological approaches represented by MR enterography, following administration of an oral contrast medium, and MR enteroclysis, following administration of contrast medium through a nasojejuneal tube. MRI may be used to demonstrate the pathologic findings and complications of CD. In particular, MR has excellent sensitivity and specificity, ranging from 88%-98% and 78%-100%, respectively, for the detection of active inflammation, wall thickening, ulcerations, increased wall enhancement, increased vascularity, perienteric inflammation, and reactive adenopathy. MR also allows more accurate identification of associated complications including penetrating and fibrostenotic disease as well as the more rare extraintestinal manifestations that are usually associated with severe and longstanding intestinal inflammation, the latter often guiding the therapeutic approach. In the progression of CD some rare complications can occur that, to our knowledge, were only briefly or never mentioned in the radiological literature regarding MR enterography or enteroclysis and in which the application of these techniques play a key role.

Muscle fat fraction in neuromuscular disorders: dual-echo dual-flip-angle spoiled gradient-recalled MR imaging technique for quantification--a feasibility study

PURPOSE

To prospectively evaluate the muscle fat fraction (MFF) measured with dual-echo dual-flip-angle spoiled gradient-recalled acquisition in the steady state (SPGR) magnetic resonance (MR) imaging technique by using muscle biopsy as the reference standard.

MATERIALS AND METHODS

After ethics approval, written informed consent from all patients was obtained. Twenty-seven consecutive patients, evaluated at the Neuromuscular Disorders Center with a possible diagnosis of neuromuscular disorder, were prospectively studied with MR imaging of the lower extremities to quantify muscle fatty infiltration by means of MFF calculation. Spin-density- and T1-weighted fast SPGR in-phase and opposed-phase dual-echo sequences were performed, respectively, with 20° and 80° flip angles. Round regions of interest were drawn by consensus on selected MR sections corresponding to anticipated biopsy sites. These were marked on the patient's skin with a pen by using the infrared spider light of the system, and subsequent muscle biopsy was performed. MR images with regions of interest were stored on a secondary console where the MFF calculation was performed by another radiologist blinded to the biopsy results. MFFs calculated with dual-echo dual-flip-angle SPGR MR imaging and biopsy were compared by using a paired t test, Pearson correlation coefficient, and Bland-Altman plots. P value of < .05 was considered to indicate a statistically significant difference.

RESULTS

The mean MFFs obtained with dual-echo dual-flip-angle SPGR MR imaging and biopsy were 20.3% (range, 1.7%-45.1%) and 20.6% (range, 3%-46.1%), respectively. The mean difference, standard deviation of the difference, and t value were -0.3, 1.3, and -1.3 (P > .2), respectively. The Pearson correlation coefficient was 0.995; with the Bland-Altman method, all data points were within the ± 2 SDs limits of agreement.

CONCLUSION

The results show that dual-echo dual-flip-angle SPGR MR imaging technique provides reliable calculation of MFF, consistent with biopsy measurements.

MR imaging findings of focal myositis: a pseudotumour that may mimic muscle neoplasm

OBJECTIVE

The authors describe magnetic resonance (MR) findings in eight patients with histologically confirmed focal myositis.

MATERIALS AND METHODS

In each patient, axial TSE T1-weighted and fast short-tau inversion recovery (STIR) images were obtained using a 1.5-T MR scanner. Three patients also underwent dynamic contrast-enhanced MR examination using a GE T1-weighted sequence. The following features were evaluated: anatomical distribution, extent of the involvement, signal intensity characteristics, dynamic enhancement pattern and outcome at follow-up examinations.

RESULTS

Seven of eight lesions were located in the lower extremities, one of eight in the arm; four of eight involved part of a muscle, two of eight diffusely involved a muscle and two of eight showed multifocal involvement of two or more muscles. All lesions were hyperintense on fast-STIR images: the hyperintensity was homogeneous in six of eight and inhomogeneous in two of eight. On T1-weighted unenhanced images, all lesions but two appeared isointense or slightly hypointense in comparison to normal muscles; two lesions showed a slight hyperintensity. Dynamic enhancement pattern corresponded to the type usually seen in benign soft tissue lesions. All lesions disappeared.

CONCLUSION

Focal myositis is an uncommon pseudotumour which should be considered in the differential diagnosis of muscular masses and myopathies.

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.

Complex cystic renal masses: characterization with contrast-enhanced US

PURPOSE

To prospectively compare contrast material-enhanced ultrasonography (US) with computed tomography (CT) in the classification of complex cystic renal masses with the Bosniak system.

MATERIALS AND METHODS

Ethics committee approval and written informed consent were obtained. Forty patients (17 women, 23 men; age range, 31-77 years) with 44 complex cystic renal masses detected with conventional US were prospectively examined by using second-harmonic US with a second-generation contrast agent and multiphasic helical CT. Thirty-six patients had one lesion, and four patients had two lesions. Surgical resection in nine patients and imaging follow-up in 31 patients were used to determine the outcome.

RESULTS

On contrast-enhanced US images, masses were classified as Bosniak category II (n = 18), IIF (ie, lesions were classified as category II and follow-up was needed) (n = 16), III (n = 7), or IV (n = 3) lesions. On CT images, masses were classified as Bosniak category II (n = 24), IIF (n = 10), III (n = 7), or IV (n = 3) lesions. Interobserver agreement was high (kappa = 0.86, P < .001) for classification with US. Complete concordance between the readers was found for classification with CT. Complete concordance between contrast-enhanced US and CT was observed in the differentiation of surgical and nonsurgical complex cysts. Complete concordance among the three readers in the assessment of vascularity with contrast-enhanced US was found. Interobserver agreement in the evaluation of enhancement on CT images was high (kappa = 0.88, P < .001). Concordance between contrast-enhanced US and CT in the evaluation of vascularization was high (kappa = 0.77, P < .001).

CONCLUSION

The study data suggest that contrast-enhanced second-harmonic US is appropriate for renal cyst classification with the Bosniak system.

Evaluation of the anterior ethmoidal artery by 3D dual volume rotational digital subtraction angiography and native multidetector CT with multiplanar reformations. Initial findings

Our purpose is to codify the anterior ethmoidal artery (AEA) course and its relationship with adjacent structures. Twenty patients with cerebrovascular disease underwent selective internal carotid dual volume angiography. Fusion of the vascular and bony images was obtained successively on a second console. MDCT of the cranium was performed in all patients. To identify the AEA course, multiplanar CT reformations were obtained. In all cases the entry-point of AEA and its course were identified by means of dual volume angiography. The information was confirmed by MDCT. In a second phase, we studied another 78 patients affected by inflammatory disease and polyposis only by means of MDCT, in order to confirm the previous data obtained by comparison between angiography and MDCT. In this second phase, 110/156 vessels were indirectly detected by means of visualization of the ethmoidal entry point. In the remaining cases, AEA was directly shown due to integrity of the thin ethmoidal bone lamellae or bony canal. Dual volume angiography is essential to identify the course of the AEA (standard of reference for the interpretation of CT). In patients with benign rhinosinusal pathology, where invasivity techniques are not justified, MPR reconstructions were of pivotal importance in the evaluation of the course of the artery with particular reference to its relationship with the frontal recess.

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.

"Dropped-head" syndrome due to isolated myositis of neck extensor muscles: MRI findings

MRI findings of a patient with dropped-head syndrome due to focal myositis of the neck extensor muscles are presented. MRI showed oedematous changes and marked enhancement of the neck extensor muscles. After therapy MRI demonstrated disappearance of the abnormal findings.

Multiple hypervascular pancreatic metastases from renal cell carcinoma: dynamic MR and spiral CT in three cases

Pancreatic metastases are rare. Melanoma, lung cancer and breast carcinoma are the most common origin of pancreatic metastases, whereas renal cell carcinoma is counted in only 1-2%. Renal cell carcinoma usually leads to a solitary pancreatic metastasis, whereas multiple pancreatic metastases are uncommon. We present three cases of multiple hypervascular pancreatic metastases from renal cell carcinoma, studied with spiral CT and dynamic MR.

Contrast-enhanced second-harmonic sonography in the detection of pseudocapsule in renal cell carcinoma

OBJECTIVE

Our purpose was to assess the capacity of contrast-enhanced second-harmonic sonography to detect a pseudocapsule in renal masses compared with conventional gray-scale sonography. SUBJECTS AND METHODS. Thirty-two patients with 40 renal masses suspicious for renal cancer (mean diameter, 3.1 cm) were prospectively studied with contrast-enhanced second-harmonic sonography during IV administration of a second-generation sonographic contrast agent. The sonographic criteria for the presence of a pseudocapsule were a peritumoral hypoanechoic halo on conventional gray-scale imaging and a rim of perilesional enhancement, increasing in the tardive phase of the examination, on contrast-enhanced second-harmonic imaging. Multiphasic helical CT or dynamic MRI or both were performed in all patients.

RESULTS

Final diagnoses of the 40 renal masses were as follows: hemorrhagic cysts, five; angiomyolipomas, four; lymphomas, four; metastasis from lung cancer, one; and renal cell carcinomas (RCCs), 26. Histologic diagnosis of RCC was surgically obtained in all patients. Nephron-sparing surgery was performed in 12 of 26 RCCs, and radical nephrectomy was performed in the remaining 14. At pathologic examination, pseudocapsule was found in 14 (53.8%) of 26 RCCs. On conventional sonography, the presence of a pseudocapsule was detected in 3 of 14 RCCs (sensitivity, 21%). Sonographic contrast-enhanced harmonic imaging revealed the presence of pseudocapsule in 12 of 14 RCCs (sensitivity, 85.7%). In the remaining 12 RCCs with either absent or extensive neoplastic infiltration of pseudocapsule seen at pathologic evaluation, pseudocapsule was not visible on either conventional or contrast-enhanced second-harmonic sonography. The pseudocapsule was not visible in any of the 14 noncancerous renal masses on either conventional or contrast-enhanced sonography.

CONCLUSION

Sonographic contrast-specific imaging with a second-generation contrast agent is effective in improving the sonographic visualization of tumoral pseudocapsule. This finding could be useful both in the sonographic diagnosis and in the choice of conservative surgery for renal cell carcinoma. The potential role of second-harmonic contrast-enhanced sonography in the management of renal cell carcinoma should be investigated in larger series and compared with the findings of state-of-the-art MRI and CT.

Virtual endoscopy of the nasopharynx in the evaluation of its normal anatomy and alterations due to lymphoid hyperplasia: preliminary report

The purpose of this study was to evaluate the diagnostic usefulness of virtual endoscopy in establishing the anatomic appearance of nasopharynx, both normal and affected by lymphoid hyperplasia. Thirty-seven patients affected by chronic rhinosinusal and otomastoid pathology, all studied by rhinoscopy, were examined with multislice computed tomography (CT) and virtual endoscopy of the nasopharynx. Rhinoscopy showed a completely normal nasopharynx in 15 cases and a variable grade of lymphoid hypertrophy in 22 patients. A general agreement was observed between traditional and virtual endoscopy findings in both subgroups. The tasca of Luschka was detected in 13/15 of normal subjects and only in 3/22 patients. The Rosenmuller fossae appeared deeper in normal subjects and their symmetry could be considered an important criterion of normality. In all cases, a good evaluation of the tubaric ostium was obtained. Differentiation between hyperplasic lymphoid tissue and neoplasms is possible only in lymphoid hyperplasia characterized by median crest-like swelling with a narrow base. In most cases, differential diagnosis cannot be based only on morphological criteria of virtual endoscopy, but it should be evaluated considering the overall CT findings and clinical presentation.

Harmonic US imaging of vesicoureteric reflux in children: usefulness of a second generation US contrast agent

BACKGROUND

Contrast-enhanced voiding urosonography (VUS) is largely accepted both for the diagnosis and follow-up of vesicoureteric reflux (VUR) in children.

OBJECTIVE

To evaluate the usefulness of contrast-enhanced second-harmonic VUS in the diagnosis and grading of VUR, using a second-generation contrast agent.

MATERIALS AND METHODS

Eighty consecutive children were prospectively studied with contrast-enhanced second-harmonic VUS. All children received a second-generation contrast medium, constituted by phospholipid-stabilized microbubbles of sulphur-hexafluoride (SonoVue, Bracco, Milan, Italy). US monitoring of the bladder, of the retrovesical space and of the kidneys was performed using, alternatively, both tissue-harmonic and contrast-harmonic modes. In those young boys where VUR was depicted at VUS, examination was completed with transperineal, sagittal urethral exploration during micturition. VUR was graded in five steps and diagnoses were compared with voiding cystourethrography (VCUG).

RESULTS

VUR was diagnosed in 52 reno-ureteral units with VUS. In 49 of these reno-ureteral units, VCUG confirmed the presence of VUR. In comparison to VUS, sensitivity and negative predictive value of VCUG were inferior. The grade of VUR detected at VUS was higher than that detected at VCUG in three units. In no case was the grade of VUR detected at VCUG higher than the one detected at VUS. The differences between VUS and VCUG in grading VUR were statistically significant (p=0.02). Imaging of the normal posterior urethra was skilfully demonstrated with US in 15 young boys with VUR. No statistically significant differences were found between tissue-harmonic and contrast-harmonic mode (p=0.102).

CONCLUSIONS

Contrast-enhanced second-harmonic VUS is a sensitive and easy technique for the evaluation of VUR. A second-generation US contrast medium such as SonoVue, if available, should be the first choice as the dose required for one examination is much lower and consequently significant reduction of contrast agent cost is possible.

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.

Patterns of recurrence of bronchioloalveolar cell carcinoma after surgical resection: a radiological, histological, and immunohistochemical study

PURPOSE

Bronchioloalveolar carcinoma (BAC) is a subtype of lung adenocarcinoma whose incidence is raising. Bronchioloalveolar carcinoma has a tendency to involve diffusely the lung. No agreement exists about whether diffuse bronchioloalveolar carcinoma has a multicentric or unicentric origin. The purpose of this work is to evaluate the correlation between intrapulmonary spread of bronchioloalveolar carcinoma and its histologic and immunohistochemical characteristics.

DESIGN

Surgical specimens of 20 bronchioloalveolar carcinomas with radiologically proved evolution from focal to diffuse disease were retrieved and reviewed. Patterns of pulmonary spread were defined on the basis of CT and MR imaging examinations. Immunohistochemical studies were performed to investigate the expression of gelatinase A and alpha2-integrin. Correlation between immunohistochemical results and patterns of pulmonary spread was evaluated. Statistical evaluation was performed by using Fisher Exact Test.

RESULTS

Three histological subtypes of bronchioloalveolar carcinoma were found: mucinous (11 cases), non-mucinous (3 cases), and mixed adenocarcinoma with prominent bronchioloalveolar pattern (6 cases). Three patterns of pulmonary spread were depicted radiologically: parenchymal opacification (11 cases), multiple nodules (7 cases) and mixed pattern (2 cases). Eleven out of 12 mucin-producing versus none out of 8 non-mucin producing cancers developed parenchymal opacification. The difference was statistically significant (P<0.028). A statistically significant difference was also found between the development of parenchymal opacification and the level of alpha2-integrin: 11 out of 13 tumors with negative alpha2-integrin versus none out of 7 with positive alpha2-integrin immunoreactivity (P>0.033).

CONCLUSIONS

Diffuse bronchioloalveolar carcinoma may develop from a prior focal cancer. Mucinous subtype is the most prone to develop diffuse disease with parenchymal opacification, probably representing aerogenous spread. Low levels of alpha2-integrin receptors were found in bronchioloalveolar carcinoma which developed parenchymal opacification.