Improvement of vascular signal intensity in contrast-enhanced MRA with Gd-BOPTA: comparison with Gd-DTPA.
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Carotid Stenosis↗
Biomedical subjects
Roberto Passariello
Publications and source records attributed to Roberto Passariello.
Oral contrast agents for magnetic resonance imaging of the bowel.
The development of fast imaging sequences, which provide the ability to acquire motion-free T1- and T2-weighted images of static fluids, has greatly increased the interest in magnetic resonance imaging of the small bowel. Luminal distension is a necessary prerequisite for small bowel imaging methods because collapsed bowel loops can hide even large lesions and may mimic wall thickening. Poor distension of normal bowel loops in basal conditions has led researchers to study different oral contrast media to optimally distend the bowel lumen. Several MR oral contrast agents with various signal properties are available. According to these signal properties, agents are classified as positive ("bright" lumen), negative ("dark" lumen), or biphasic ("bright" lumen on T1 and "dark" on T2, or conversely "dark" lumen on T2 and "bright" on T1). Positive contrast agents cause a reduction in T1 relaxation time; consequently, these agents act on T1-weighted images by increasing the signal intensity of the bowel lumen. Negative contrast agents are based on superparamagnetic particles and act by inducing local field inhomogeneities, which results in shortening of both T1 and T2 relaxation times. Using superparamagnetic contrast agents, T2-weighted effects are predominant. Biphasic contrast agents are substances that have different signal intensities on different sequences, depending on the concentration at which they are administered. The choice of a single agent presents advantages and disadvantages; thus, the radiologist should choose the appropriate contrast medium according to the clinical setting, MR experience, availability of the agent, and patient tolerance.
Administration, Oral↗
[Study of the mesenteric arteries with multislice spiral CT angiography].
The aim of our study was to optimize an high-resolution CT angiography protocol for the evaluation of mesenteric arteries using a multislice spiral CT equipment. A volumetric dataset was acquired during dynamic i.v. injection of non-ionic iodine contrast medium; images were subsequently reconstructed by means of a dedicated off-line workstation, equipped with volume-rendering software. Excellent depiction of the anatomy of mesenteric arteries and collateral vessels was obtained in all the cases. In conclusion, new multislice spiral CT scanners allow an optimal noninvasive evaluation of mesenteric arteries, possible up to now only with catheter angiography.
Aged↗
Determining the optimal timing for early arterial phase hepatic CT imaging by measuring abdominal aortic enhancement in variable contrast injection protocols.
OBJECTIVE: To find the optimal scan timing for early arterial phase hepatic CT with adequate arterial enhancement after the aortic contrast arrival. METHODS: Sixty patients were divided randomly into three groups, each of which received 2.0 mL/kg of the 300 mgI/mL contrast medium with an injection duration of 30 seconds (Group A, mean rate 3.6 mL/sec); of 25 seconds (B, 4.6 mL/sec); of 30 seconds (3.6 mL/sec) followed by a saline chaser (C). RESULTS: After the contrast arrival, aortic enhancement increased rapidly for 6-15 seconds (mean, 10 seconds) to the initial peak enhancement in all groups, and then, increased moderately to the maximum aortic enhancement over the following 19, 13, and 21 seconds, respectively. The mean maximum aortic enhancement in Group B (392 HU) and C (360 HU) were significantly higher than that in A (326 HU), respectively. The difference between the initial and maximum aortic enhancement was less than 50 HU. CONCLUSION: The optimal timing of the early arterial phase for hepatic CT arteriography is 10-15 seconds after the aortic arrival.
Adult↗
Computed tomography angiography: state-of-the-art imaging using multidetector-row technology.
Multidetector-row computed tomography (MDCT) is an essential diagnostic modality for many clinical algorithms. This is particularly true with regard to the evaluation of cardiovascular disease. As a result of increased image acquisition speed, improved spatial resolution, and greater scan volume, MDCT angiography (computed tomography angiography [CTA]) has become an excellent noninvasive imaging technique, replacing intra-arterial digital subtraction angiography for most vascular territories. The clinical success of CTA depends on precise synchronization of image acquisition with optimal vascular enhancement. As technology continuously evolves, however, this task can be challenging. It remains important to have a fundamental knowledge of the principles behind technical parameters and contrast medium administration. This article reviews these essential principles, followed by an overview of current clinical applications.
Angiography↗
Preoperative staging of rectal cancer with MR Imaging: correlation with surgical and histopathologic findings.
Rectal cancer is a common malignancy that continues to have a highly variable outcome, with local pelvic recurrence after surgical resection usually leading to incurable disease. The success of tumor excision depends largely upon accurate tumor staging and appropriate surgical technique, although the results of recent surgical trials indicate that evaluation of the involvement of the mesorectal fat and mesorectal fascia is even more important than T staging for treatment planning. Magnetic resonance (MR) imaging is increasingly being used to evaluate tumor resectability in patients with rectal cancer and to determine which patients can be treated with surgery alone and which will require radiation therapy to promote tumor regression. High-spatial-resolution MR imaging has proved useful in clarifying the relationship between a tumor and the mesorectal fascia, which represents the circumferential resection margin at total mesorectal excision. Phased-array surface coil MR imaging in particular plays a vital role in the therapeutic management of rectal cancer. At present, phased-array MR imaging best fulfills the clinical requirements for preoperative staging of rectal cancer. However, preoperative evaluation of the other prognostic factor, nodal status, is still problematic, and further studies will be needed to better define the role of MR imaging in this context.
Humans↗
Multislice spiral CT colonography in the evaluation of colorectal neoplasms.
PURPOSE: The purpose of our study was to evaluate the efficacy of multislice spiral CT colonography: 1) in the diagnosis and staging of colorectal carcinoma; 2) in the evaluation of the proximal colon in patients with stenosing neoplasms. MATERIALS AND METHODS: There were 33 patients (21 males and 12 females) with known colorectal carcinoma diagnosed by conventional colonoscopy. All patients enrolled in the study underwent both conventional colonoscopy followed by CT colonography on the same day. CT examination was performed using a multislice spiral CT scanner (Somatom Plus 4 Volume Zoom; Siemens, Erlangen, Germany). Imaging parameters were: slice collimation, 1 mm; slice thickness, 1 mm; table speed, 8 mm/sec; reconstruction interval, 1 mm; mAs, 80; kVp, 120; acquisition time, 25-32 sec. Image analysis was performed using a software package with volume-rendering capabilities (Vitrea 2.6; Vital Images, Minneapolis, USA). Image analysis consisted in the evaluation of: 1) number, size, and location of the lesions; 2) primary tumor staging. For the purposes of tumor staging, we utilized the TNM staging system. For the evaluation of parameters T and N, histologic examination on resected surgical specimens and lymph nodes served as the standard of reference. The presence of hepatic metastases was confirmed by means of partial surgical resection in patients with single metastasis or by means of intraoperative ultrasonography in patients with multiple metastases. RESULTS: Conventional colonoscopy detected 33 carcinomas and 4 polyps and was incomplete in 9 cases (27.2% of all examinations) due to stenosing lesions. CT colonography provided adequate visualization of the whole colon in all patients with identification of 35 carcinomas (33 primary and 2 synchronous) and 10 polyps. Therefore, CT colonography correctly detected all lesions seen at conventional colonoscopy and yielded the additional identification of 2 synchronous tumors and 6 polyps located in the colon proximal to the primary stenosing neoplasm. Primary tumor staging with CT colonography was correct in 32 of 33 patients (accuracy, 96.9%) CONCLUSIONS: Multislice spiral CT colonography detected all primary neoplasms, provided correct staging of 96.9% of tumors and visualized the whole colon even in patients with stenosing lesions. Considering the current limitations of the other procedures and the possibility of assessing both the colon and the extracolonic structures, multislice spiral CT colonography can be proposed as the initial diagnostic modality for pre-operative evaluation of patients with colorectal carcinoma.
Aged↗
Magnetic Resonance in the study of the small bowel.
Magnetic resonance (MR) of the small bowel is a field of application which for many years received little attention, being limited to advanced and selected research centres whose studies had no real clinical impact. Even after the first two publications in 1985, it was not until 1998 and the following years that a decisive improvement in scientific research articles was observed. This was largely due to the need for progressive development of adequate technologies, in particular fast imaging. Although the major technological problems have now been resolved, the optimisation of the study protocol is still under evaluation. In this regard there are two main methodological approaches: 1) "MR follow-through" following administration of an oral contrast medium; 2) "MR enteroclysis", following administration of contrast medium through a nasojejunal tube. Several contrast media are currently available for small bowel study, and they are classified according to signal intensity into positive, negative or biphasic. Biphasic agents are those most commonly used for both MR follow-through and MR enteroclysis. The major clinical indication for a study of the small bowel with MR is the evaluation of chronic inflammatory disease (Crohn's disease). Considerable experience has been obtained over the past years, with the consequent introduction of MR in routine clinical practice in many centres worldwide. Other potential clinical indications, at the moment to be considered work-in-progress, are the evaluation of malabsorption syndromes (and among them, celiac disease) and assessment of neoplastic diseases.
Administration, Oral↗
MR of the small bowel with a biphasic oral contrast agent (polyethylene glycol): technical aspects and findings in patients affected by Crohn's disease.
PURPOSE: To report our experience using MR of the small bowel with polyethylene glycol (PEG) solution as an oral contrast agent in a population of adults and children with known Crohn's disease. MATERIALS AND METHODS: 40 patients (29 males; 11 females), 15 adults (age range 24-52 years) and 25 children (age range 5-17 years), with known Crohn's disease, underwent MR of the small bowel using a supeconductive 1.5 T magnet, and polyethylene glycol solution as an oral contrast agent. The fixed amount of contrast agent was 750-1000 ml for adults and 10 ml/kg of body weight for children. The Crohn's Disease Activity Index (CDAI) was available in all patients. Our study protocol included the acquisition of T2-weighted half-Fourier single-shot turbo spin-echo (HASTE) sequences and true fast imaging in the steady-state precession (true-FISP) sequences, followed by the acquisition of "spoiled" 2D gradient echo T1-weighted sequences with fat suppression (FLASH, fast low-angle shot) or alternatively "spoiled" 3D (VIBE, volume interpolated breath-hold examination), acquired 70 seconds after intravenous administration of gadopentetate dimeglumine (Gd-DTPA) (0,1 mmol/kg). A specific MR score was created and calculated for each patient and was compared by means of the Spearman rank with CDAI. RESULTS: In all patients no significant side effects were observed and the MR examination was well tolerated even by paediatric patients. In all cases MR showed a small bowel wall thickening (> 4 mm) in the terminal ileum, with lumen stenosis in 26 patients. In 3 cases pathological segments proximal to the terminal ileum were observed and in another 3 cases caecal involvement was visible. The MR examination was able to show abnormalities of perivisceral fat tissue in 15 patients, mesenteric lymphadenopathy in 1 patient and abdominal abscess in 1 case. The Spearman rank showed a statistically significant correlation between CDAI and the MR score (r = 0.91, P = 0,0001). DISCUSSION: MR using PEG as an oral contrast agent could be considered a test of great interest in the evaluation of the small bowel in patients suspected of having Crohn's disease in that it is easily reproducible, well tolerated even by paediatric patients and it provides useful information about the localisation, extension and activity of inflammatory disease without the use of ionising radiation.
Administration, Oral↗
Gadobenate dimeglumine (Gd-DTPA) vs gadopentetate dimeglumine (Gd-BOPTA) for contrast-enhanced magnetic resonance angiography (MRA): improvement in intravascular signal intensity and contrast to noise ratio.
PURPOSE: The purpose of this study was to compare contrast enhanced MR angiography (MRA) with gadopentetate dimeglumine (Gd-DTPA) to MRA with gadobenate dimeglumine (Gd-BOPTA), a high relaxivity paramagnetic contrast agent. MATERIALS AND METHODS: Twelve patients referred for carotid artery stenosis were examined with MR angiography using a fast spoiled gradient echo sequence. Gd-DTPA and Gd-BOPTA enhanced MR angiography were performed within 48-72 hours using a dose of 0.1 mmol/kg for Gd-BOPTA and 0.2 mmol/kg for Gd-DTPA, at a flow rate of 2 ml/s. Images were evaluated by two blinded radiologists. Qualitative and quantitative evaluations were performed comparing the sets of images from the two examinations. RESULTS: Qualitative evaluation demonstrated superior arterial contrast enhancement and vessel conspicuity with Gd-BOPTA compared with Gd-DTPA. Quantita-tive evaluation showed an improvement in both signal intensity and contrast to noise ratio with Gd-BOPTA. CONCLUSION: The greater relaxivity of Gd-BOPTA, at lower doses, compared with Gd-DTPA, provides higher intravascular signal and signal to noise ratio. Gd-BOPTA appears to be an optimal contrast agent for contrast enhanced MRA.
Carotid Stenosis↗
Contrast-enhanced US in the assessment of the ilio-caval axis in deep venous thrombosis.
PURPOSE: To assess the feasibility and the accuracy of a new technique in the evaluation of deep venous thrombosis (DVT) in the ilio-caval axis. MATERIALS AND METHODS: Thirty-eight patients with suspected DVT were prospectively examined with unenhanced and enhanced colour-Doppler ultrasonography, and ascending contrast venography. Thirty-five out of 38 patients underwent US phlebography, consisting in manual injection of Levovist (Schering Ag, Berlin, Germany) through a 21-G cannula in a suitable dorsal vein of the foot ipsilateral to the suspected DVT. Three patients in whom it was not possible to cannulate a dorsal vein of foot underwent contrast-enhanced US after injection of Levovist through an antecubital vein, but where excluded from the present study. A contrast venogram was nonetheless carried out in all out three patients for comparison with the US-phlebography findings. RESULTS: US-phlebography allowed better definition of the presence and extension of deep vein thrombosis in all patients, when compared to conventional color-Doppler US. In the evaluation of suspected acute thrombosis, the comparative efficacy of Doppler-US and US phlebography compared with ascending phlebography as the gold standard, was as follows: sensitivity of 85.7% and 90%, specificity of 71.4 and 100%, accuracy of 80.9 and 95.2%, PPV of 85.7, and 100%, and NPV of 71.4, and 75%, respectively. In the assessment of chronic thrombosis, US and US phlebography achieved a sensitivity of 90% and 100%, a specificity of 75% and 100%, an accuracy of 85.7% and 100%, a PPV of 100, 100%, a NPV of 87.5, 100%, respectively. No complications related to US phlebography were observed. CONCLUSIONS: US-phlebography is a promising tool in the assessment of deep vein thrombosis, being highly accurate and feasible. However, further studies based on larger series are mandatory to confirm our promising results and establish a standardised role for this new technique.
Acute Disease↗
Comparison of diagnostic performance of unenhanced vs SonoVue - enhanced ultrasonography in focal liver lesions characterization. The experience of three Italian centers.
PURPOSE: To evaluate the diagnostic performance of contrast-enhanced US with SonoVue (Bracco, Milan, Italy) compared to baseline US in focal hepatic lesions characterization. MATERIALS AND METHODS: A comprehensive number of four operators from 3 hospitals evaluated 57 consecutive patients with 60 focal hepatic lesions (28 hepatocellular carcinomas, 11 metastases, 13 hemangiomas, 1 hepatocellular adenoma and 7 focal nodular hyperplasias) by baseline gray-scale ultrasound (US) and color Doppler US. The same lesions were subsequently scanned by contrast-enhanced US after intravenous bolus administration of 2,4-4,8 ml of SonoVue by employing intermittent high or continuous low transmit power imaging. The diagnosis of lesions nature (benign or malignant) and histotype proposed by the on-site operator was finally compared to the definite diagnosis reached by reference procedures (multiphasic contrast-material enhanced helical-computed tomography or magnetic resonance in 24 lesions and fine needle US guided biopsy in 36 lesions). Diagnostic performance (sensitivity, specificity and overall accuracy expressed by the agreement with the reference procedures) of baseline and contrast enhanced US were compared. RESULTS: Differences in sensitivity (baseline vs contrast-enhanced US: 13/39 [33%] vs 32/39 [82%]), specificity (baseline vs contrast-enhanced US: 12/21 [57%] vs 16/21 [76%]) and overall accuracy (baseline vs contrast-enhanced US: 25/60 [41%] vs 47/60 [78%]) were significant (p<0.05; McNemar test). CONCLUSIONS: SonoVue-enhanced US determined a significant improvement in diagnostic performance in the characterization of focal liver lesions if compared to baseline US.
Adenoma, Liver Cell↗
CE-Magnetic Resonance Mammography for the evaluation of the contralateral breast in patients with diagnosed breast cancer.
PURPOSE: To evaluate the role of contrast-enhanced Magnetic Resonance Mammography (MRM) in the evaluation of the contralateral breast in patients with recently diagnosed breast cancer. MATERIALS AND METHODS: Fifty patients with proved unilateral breast cancer, with a negative contralateral breast at physical examination, ultrasound and mammography, were studied with a 1.5 T magnet (Siemens, Vision Plus, Germany). A bilateral breast surface coil was used. Dynamic 3D Flash T1-weighted sequences were acquired in the axial plane before and 0, 2, 4, 6 and 8 minutes after the administration of 0.1 mmol/kg of Gd-BOPTA at a flow rate of 2 ml/s followed by 10 ml of saline. The level of suspicion was reported on a scale from 0 to 5 following the BI-RADS classification, based on lesion morphology and kinetic features. The results were compared with the histological findings after biopsy or surgery. RESULTS: Fourteen out of 50 patients (28%) had contralateral lesions identified on MRM. Biopsy was performed in four of them for suspicious lesions (BI-RADS 4) while 10 patients underwent surgery because of highly suggestive malignant lesions (BI-RADS 5). Histology diagnosed three fibroadenomas, 5 ductal carcinomas in situ, 2 lobular carcinomas in situ, 3 invasive ductal carcinomas and 1 invasive lobular carcinoma. Contrast-enhanced MRM yielded no false negative and three false positives. CONCLUSIONS: Our results demonstrate a very good accuracy of Magnetic Resonance Mammography in the detection of synchronous contralateral cancer in patients with newly diagnosed breast cancer. Therefore, contrast-enhanced MRM could be introduced to screen patients with proven breast cancer before they undergo surgery.
Adult↗