MRI in the diagnosis of small bowel disease: use of positive and negative oral contrast media in combination with enteroclysis

The aim of the study was to evaluate the additional findings of MRI following small bowel enteroclysis and to compare the efficacy of negative and positive intraluminal contrast agents. Fifty patients with inflammatory or tumorous small bowel disease were investigated by small bowel enteroclysis and consecutive MRI using breathhold protocol (T1-weighted fast low-angle shot, T2-weighted turbo spin echo). Patients were randomly assigned to either receiving a positive oral (Magnevist, Schering, Berlin, Germany) or a negative oral MR contrast media (Abdoscan, Nycomed, Oslo, Norway). The pattern of contrast distribution, the contrast effect, presence of artifacts, as well as bowel wall and extraluminal changes, were determined and compared between the contrast type using Fischer's exact test. Sensitivity, specificity, and diagnostic accuracy for MRI and enteroclysis were calculated. Twenty-seven patients had clinically proven Crohn's disease and two patients surgically proven small bowel tumours. Magnetic resonance imaging had important additional findings as abscesses and fistulae in 20 patients. Surgically compared sensitivities were 100 and 0 % for MRI and enteroclysis, for the detection of abscesses, and 83.3 and 17 % for the diagnosis of fistulae, respectively. Bowel wall thickening was more reliably detected with use of positive oral contrast media without intravenous enhancement (p < 0.001), whereas postcontrast negative oral contrast media allow for a superior detection (p < 0.001). T2-weighted sequences were necessary with use of negative oral contrast media, because loop abscesses may be masked. Magnetic resonance imaging should be performed in all patients with suspicion of extraintestinal complications, because the complications are more reliably detected by MRI. Negative oral contrast media show advantages with the use of intravenous contrast but can mask loop abscesses using only T1-weighted imaging. Received: 5 March 1999; Revised: 21 September 1999; Accepted: 3 February 2000     

Efficacy of the spiral flow generating extended tube during paediatric CCTA

IntroductionTo compare the computed tomography (CT) number for paediatric cardiac computed tomography angiography (CCTA) and visualisation score of the three-dimensional (3D) images using the conventional T-shaped extended tube (T-tube) and spiral flow-generating extended tube (spiral-tube) connected between the contrast injector and cannula.MethodsIn total, 108 patients suspected to have congenital heart disease (CHD) were considered for inclusion. We utilised the T-tube for intravenous contrast and spiral-tube in 54 patients each. Observers individually inspected randomized volume rendering images of the internal thoracic artery, each acquired from the with or without spiral-tube groups, using a four-point scale. We compared the mean CT number of the ascending aorta (AAO) and pulmonary artery (PA), contrast noise ratio (CNR), CT number for the AAO and PA enhancement ratio, and the visualisation scores between the groups.ResultsThere were no significant differences in patient characteristics between the with or without spiral-tube groups (p > 0.05). The mean CT number ±standard deviation for the AAO and PA, and the CNR without or with spiral-tube groups were 441.2 ± 89.2 and 489.8 ± 86.1 HU for the AAO, 436.3 ± 100.6 and 475.3 ± 85.2 HU for the PA, and 9.5 ± 2.2 and 10.8 ± 2.4 for the CNR, respectively (p < 0.05). In the spiral-tube group, the CT number, CNR, and visualisations score of the 3D images were significantly higher for the AAO and PA than those in the T-tube group (p < 0.05).ConclusionThe spiral-tube proved to be beneficial in improving the CT number for the AAO and PA, CNR, and visualisation score compared with the conventional T-tube during paediatric CCTA.Implications for practiceThe spiral-tube may allow the visualisation of smaller blood vessels than those visualised by the conventional T-tube for paediatric patients in CCTA.     

Breathhold MRI of the small bowel in Crohn's disease after enteroklysis with oral magnetic particles

Purpose: To evaluate the efficacy of breathhold MRI following enteroclysis with addition of oral magnetic particles to study the extension, detection of stenoses and extraluminal manifestations in Crohn's disease. Material and Methods: 18 patients with Crohn's disease and potential of surgical intervention were studied with enteroclysis with addition of oral magnetic particles. T1-/T2-weighted breathhold MRI w/o spectral fat suppression w/o i. v. Gd-DTPA was applied. Results: Typical findings were marked bowel wall thickening with strong contrast enhancement. 95.8 % of affected small bowel segments and 94.7 % of stenoses were correctly detected by MRI. All four fistulas were detected and important extraluminal findings were seen in 6/18 patients. Additionally, one ileoileal and two ileosigmoidal adhesions, two extraluminal abscesses and affection of the right ureter were delineated. Conclusion: MRI in Crohn's disease offers the potential to avoid radiation exposure in this relatively young patient group. Important additional findings relevant to indication of surgery are seen in approximately one third of cases. The replacement of transduodenal intubation by oral contrast application remains to be further studied.      

Contrast-enhanced MR imaging of the liver: Comparison between Gd-BOPTA and mangafodipir

The purpose of the study was to evaluate the MR contrast agents gadolinium benzyloxypropionictetro-acetate (Gd-BOPTA) and Mangafodipir for liver enhancement and the lesion-liver contrast on T1W spin-echo (SE) and gradient-recalled-echo (GRE) images. Fifty-one patients (three groups of 17 patients each) with known or suspected liver lesions were evaluated with T1W SE (300/12) and GRE (77-80/2.3-2.5/80°) images before and after intravenous (IV) Gd-BOPTA (0.1 or 0.05 mmol/kg) or Mangafodipir (5 μmol/kg) in phase II to III clinical trials. Quantitative analysis by calculating liver signal-to-noise ratio (SNR), lesion-liver contrast-to-noise ratio (CNR), and spleen-liver CNR was performed. Liver SNR and spleen-liver CNR were always significantly increased postcontrast. SNR was highest after application of 0.1 mmol/kg Gd-BOPTA (51.3 ± 3.6, P < .05). CNR was highest after Mangafodipir (?22.6 ± 2.7), but this was not significantly different from others (P = .07). Overall, GRE images were superior to SE images for SNR and CNR. Mangafodipir and Gd-BOPTA (0.1 mmol/kg) provide equal liver enhancement and lesion conspicuity postcontrast. By all criteria, contrast-enhanced T1-weighted GRE were comparable to SE images.     

Intraoperative MRI to control the extent of brain tumor surgery

Purpose: The main aim of our study was to find out whether the combined use of neuronavigation and intraoperative MRI can increase the rate of “complete tumor removal”. The second aim was to characterize the different forms of surgically induced enhancement in order to differentiate them from residual tumor. Materials and methods: Surgery was performed in 18 patients with high-grade glioma. Using a neuronavigation device, the surgeons operated up to the point where they would otherwise have terminated surgery. Intraoperative MRI was then performed to determine whether residual enhancing had been left behind and to update the neuronavigation device. If necessary, feasible surgery was continued. On days 1–3 after surgery early postoperative MRI (1.5 T) was performed. The proportion of patients in whom the enhancing tumor was completely removed was compared with a series of 60 patients with glioblastoma multiforme, who had been operated on using neither neuronavigation nor intraoperative MRI . We also looked for and characterized different types of surgically induced enhancement. Results: Intraoperative MRI definitely showed residual tumor in 6 of the 18 patients and resulted in ambiguous findings in 3 patients. In 7 patients surgery was continued. Early postoperative MRI showed residual tumor in 3 patients and resulted in uncertain findings in 2 patients. The rate of patients in whom complete removal of enhancing tumor could be achieved was 50 % at the time of the intraoperative MR examination and 72 % at the time of the early postoperative MR control. The difference in proportion of patients with “complete tumor removal” between the groups who had been operated on using neuronavigation (NN) and intraoperative MRI (ioMRI) and those who had been operated on using only modern neurosurgical techniques except NN and ioMRI was statistically highly significant (Fisher exact test; P = 0.008). Four different types of surgically induced contrast enhancement were observed. These phenomena carry different confounding potentials with residual tumor. Conclusion: Our preliminary experience with intraoperative MRI in patients with enhancing intraaxial tumors is encouraging. Combined use of neuronavigation and intraoperative MRI was able to increase the proportion of patients in whom complete removal of the enhancing parts of the tumor was achieved. Surgically induced enhancement requires careful analysis of the intraoperative MRI in order not to confuse it with residual tumor.      

Characterization of the peri-infarction zone using T2-weighted MRI and delayed-enhancement MRI in patients with acute myocardial infarction

To characterize the peri-infarction zone using T2-weighted (T2w) magnetic resonance imaging (MRI) and infarct size on delayed enhancement (DE) MRI in patients with acute myocardial infarction (AMI). In 65 patients, short-axis T2w and DE MRI images were acquired 5 ± 3 d after AMI. The MRI was analyzed using a threshold method defining infarct size on DE MRI and edema on T2w MRI as areas with signal intensity larger than +2 SD above remote normal myocardium. The peri-infarction zone was calculated as the difference between the size of edema and the infarct size. The size of edema on T2w MRI (31.3 ± 13.4% of LV area) was larger than the infarct size on DE MRI (20.3 ± 10.4% of LV area, p< 0.0001). The size of the peri-infarction zone was 11.0 ± 10.0% of the LV area. Good correlation was found between infarct size on DE MRI and peak creatine kinase (CK) isoenzyme MB (r = 0.65, p< 0.0001), but there was no correlation between the size of the peri-infarction zone and CK MB (r = 0.05, p = 0.67). The peri-infarction zone was larger in patients with an infarct size <28% of the LV area (12.6 ± 10.0% LV area) compared with patients with an infarct size ≥28% of the LV area (6.7 ± 9.0% of the LV area, p< 0.05). The peri-infarction zone does not correlate with enzymatic parameters of infarct size and is substantially larger in small infarcts, indicating viable myocardium.This study was funded in part by Pinguin-Stiftung, Duesseldorf, Germany and by Schering Company, Berlin, Germany.     

Peripheral sympathetic dysfunction in patients with Parkinson’s disease without autonomic failure is heart selective and disease specific

The study was undertaken to investigate by means of iodine-123-labelled metaiodobenzylguanidine (MIBG) scintigraphy the peripheral sympathetic function in patients with Parkinson’s disease (PD) without autonomic failure and in patients with related neurodegenerative diseases with parkinsonism. Seventy patients (33 men and 37 women, mean age 63±9.7 years) with parkinsonism and ten control subjects underwent MIBG scintigraphy. Of these 70 patients, 41 were diagnosed as having idiopathic PD, 9 multiple system atrophy (MSA), 6 progressive supranuclear palsy (PSP) and 2 corticobasal degeneration (CBD); the remaining 12 were diagnosed as having neurodegenerative disease with parkinsonism (P-nism) that did not meet the diagnostic criteria of any specific disease. Cardiac planar and tomographic imaging studies and subsequent whole-body imaging were performed 20 min and 3 h after the injection of 111 MBq MIBG. The early MIBG heart to mediastinum (H/M) ratio in PD (1.61±0.29) was significantly lower than that in the control group (2.24±0.14, P<0.01), P-nism (2.15±0.31, P<0.01), MSA (2.08±0.31, P<0.05) and PSP (2.30±0.24, P<0.01). The delayed H/M ratio in PD (1.47±0.34) was also significantly lower than that in the control group (2.37±0.14, P<0.01), P-nism (2.13±0.38, P<0.01), PSP (2.36±0.36, P<0.01) and MSA (2.17±0.36, P<0.01). In patients with PD, early and delayed H/M ratios were significantly decreased in disease stages I, II and III (established using the Hoehn and Yahr criteria) as compared with control subjects, and there were no significant differences among the stages. Only PD showed a significantly higher washout rate (WR) than that in the control subjects (27%±8.0% vs 11%±4.2%, P<0.01). Early and delayed uptake ratios of the lung, parotid gland, thyroid gland, liver and femoral muscles in each of the patient groups were not significantly different from those in control subjects. Only the early and delayed uptake ratios of the lower leg muscles in MSA were significantly lower than those in the control group (P<0.05). In conclusion: In patients with PD without autonomic failure, only cardiac MIBG uptake was severely reduced in the earliest phase of the disease (stage I). Parkinsonian syndromes other than PD did not demonstrate significant reduction in MIBG uptake in any organs except for the lower legs in MSA. In patients with PD without autonomic failure, reduction in MIBG uptake occurs selectively in the heart; this is considered to be a specific finding for PD and useful for the differential diagnosis of the parkinsonian syndromes. Received 13 September and in revised form 29 December 1999     

Static and dynamic MRI of a urinary control intra-vaginal device

The aim of this study was to describe by MRI, in dynamic conditions at rest and straining, the anatomical modifications induced by a commercially available intravaginal device (IVD) aimed at relieving female stress urinary incontinence. Ten female patients complaining of stress urinary incontinence (SUI) had pelvic MRI with static and dynamic sequences, without and with a self-inserted IVD. We studied positions and angulations of the IVD in the pelvis. Paired t-test allowed comparisons of: position of the bladder neck; urethral angulation with the pubis axis; position of the urethra; and posterior urethro-vesical angle (PUVA) without and with IVD. At rest, in ten of ten cases IVD laid cranial to the pubo-rectal muscle; with an average angulation of 95 ± 10 ° with the pubis axis, laterally tilted in three of ten cases. In maximum straining with IVD bladder neck descent was lower by an average of 5.2 ± 3.1 mm (p = 0.001), pubo-urethral angle opening was smaller by an average of 22 ± 20 °(p = 0.015), and bladder neck to pubis distance was shorter by an average of 5.7 ± 4 mm. Posterior urethro-vesical angle was not significantly modified. Dynamic MRI allowed a non-invasive assessment of the mode of action of an IVD. The main modifications were a support of the bladder base and bladder neck, with a superior displacement of the urethra toward the pubis. Received: 6 October 1999; Revised: 17 January 2000; Accepted: 18 January 2000     

Intraindividual comparison of myocardial delayed enhancement MR imaging using gadobenate dimeglumine at 1.5 T and 3 T

For contrast-enhanced imaging techniques relying on strong T1 weighting, 3 T provides increased contrast compared with 1.5 T. The aim of our study was the intraindividual comparison of delayed enhancement MR imaging at 1.5 T and at 3 T. Twenty patients with myocardial infarction were examined at 1.5 T and 3 T. Fifteen minutes after injection of contrast agent (0.1 mmol gadobenate dimeglumine per kg body weight), inversion recovery gradient recalled echo (IR-GRE) sequences were acquired (1.5 T/3 T: TR 11.0/9.9 ms, TE 4.4/4.9 ms, flip 30°/30°, slice thickness 6/6 mm) to assess myocardial viability. Two observers rated image quality (Wilcoxon signed rank test). Quantification of hyperenhanced myocardium and standardized SNR/CNR measurements were performed (Student’s t test). There was no significant difference with respect to image quality (1.5 T/3 T: 3.5/3.3, p = 0.34, reader 1; 2.4/2.7, p = 0.12, reader 2) and infarction size (760 ± 566/828 ± 677 mm² at 1.5 T, 808 ± 639/826 ± 726 mm² at 3 T, reader 1/reader 2, p > 0.05). Mean SNR in hyperenhanced/normal myocardium was 19.2/6.2 at 1.5 T and 29.5/8.8 at 3 T (p < 0.05). Mean CNR was 14.3 at 1.5 T and 26.0 at 3 T (p < 0.05). Delayed enhancement MR imaging at 3 T is a robust procedure yielding superior tissue contrast at 3 T compared with 1.5 T which is, however, not reflected by increased image quality.     

Hand and wrist imaging using a low-field dedicated MRI system

Summary Purpose of this study was to evaluate the diagnostic value of a low field dedicated MRI system in hand and wrist imaging. All 308 exams of the hand and wrist, that were performed on a low-field dedicated MRI system (Artoscan, Esaote Biomedica, Italy) in our institution in 1996, and high-field MRI exams performed in addition as part of the diagnostic work-up, were evaluated and correlated to final operative (n = 64) and histologic (n = 12) reports. 90 % of all low-field MRI scans stated a diagnosis according to clinical suspicion. In 62 % the clinical question was answered, and in 26 % additional pathologies were identified. An MR-diagnosis completely different from the clinical suspicion was stated in 2 %. High field exams contributed additional information in 6 of 36 patients. In 3 patients a tumor was not shown completely in the limited field-of-view of the dedicated low-field MRI-system. Frequency-selective fat-suppression pulse sequences and a better spatial resolution were the reasons for the additional information obtained in the other three patients. Low-field dedicated MR-imaging is a valuable method in the extensive work-up of the hand and wrist. Osseous, ligamentous and tendinous pathologies are well depicted. Large or infiltrative tumors should be referred to a high-field system.      

Effect of superparamagnetic iron oxide on bone marrow

The goal of this study was to compare the effects of SPIO particles on the signal intensity of the bone marrow of the vertebra spine in patients with and without liver cirrhosis. Forty-eight patients with normal liver tissue and 56 patients with liver cirrhosis were examined before and after intravenous SPIO administration, using a 1.5-T system (Magnetom Vision, Siemens, Erlangen, Germany) with a semiflexible cp-array coil. Three different pulse sequences were applied: a T1-weighted gradient-echo sequence, a T2-weighted fast spin-echo sequence with spectral fat suppression and a T2^*-weighted gradient-echo sequence. The signal-to-noise ratio (SNR) of the liver, vertebra bone and paraspinal muscle were obtained. The SNR value change in each patient group and the SNR value difference between the two groups were evaluated. For assessment of statistical significance, Student's t-test with a level of p < 0.05 was applied. No significant differences in the SNR values of the liver and bone marrow between the two groups could be seen with any of the three sequences precontrast. Using the T1-weighted gradient-echo sequence in the noncirrhotic liver group, pre- and postcontrast comparisons of the SNR values of the liver and bone marrow indicated a decrease of approximately –44.3 % (p = 0.02) and increase of approximately 15.3 % (p = 0.04), respectively. No significant change was seen in the cirrhotic liver group. With the T2-weighted fast spin-echo sequence, a significant decrease of the SNR value of the liver and the bone marrow in both groups was seen. With the T2^*-weighted gradient-echo sequence, the signal intensity decrease of the normal liver tissue was approximately –65.6 % (p = 0.00), in cirrhotic liver tissue the decrease was –29.9 % (p = 0.02). The SNR values of the bone marrow showed a decrease of –27.8 % (p = 0.04) in the noncirrhotic liver group, whereas in the cirrhotic liver group it was only –11.3 % and statistically not significant. The effect of SPIO particles on the liver and bone marrow is significantly less in patients with liver cirrhosis. Received: 2 April 1999; Revised: 5 October 1999; Accepted: 2 February 2000     

MRI gadolinium enhancement of bone marrow: age-related changes in normals and in diffuse neoplastic infiltration

 Objective: To quantify gadolinium-related enhancement in the bone marrow of the spine in normals and in patients with homogeneous diffuse malignant bone marrow infiltration. Design and patients: The patients consisted of two groups: group 1 comprised 94 healthy adults (18–86 years) without bone marrow disease and group 2 comprised 30 patients with homogeneous diffuse malignant bone marrow infiltration due to myeloma (n=20) or breast carcinoma (n=10). All patients received intravenous gadopentetate dimeglumine (Gd-DTPA), 0.1 mmol/kg body weight. Pre- and postcontrast signal intensity (SI) on T1-weighted spin-echo (SE) images (TR/TE: 572 ms/15 ms) was measured over a region of interest (ROI) and the percentage SI increase was calculated. The results were confirmed by bone marrow biopsy (n=20) and clinical parameters (n=10). Dynamic contrast-enhanced studies using a spoiled gradient-recalled-echo (GRE) sequence (TR/TE/α: 68 ms/6 ms 75°) were performed in 10 controls with normal bone marrow. Results and conclusion: Contrast material enhancement in healthy persons can vary greatly (range 3–59%, mean 21%, SD 11%). With increasing age there is a significant decrease in contrast enhancement (Pearson’s correlation, P<0.01). The percentage SI increase in patients with intermediate-grade (biopsy 20–50 vol%) and high-grade (biopsy >50 vol%) diffuse malignant bone marrow infiltration was significantly higher than in normals (mean 67%, SD 34%, P<0.001). Low-grade (biopsy <20 vol%) diffuse malignant bone marrow infiltration can not be assessed by non-enhanced T1-weighted SE images or Gd-DTPA application. In conclusion, contrast material enhancement in healthy persons can vary greatly and is dependent on age, while intermediate-grade and high-grade diffuse malignant bone marrow infiltration can be objectively assessed with SI measurements.     

Comparison of cerebral perfusion reserve and collateral circulation in patients with internal carotid artery disease

Summary The cerebral hemodynamics in patients with carotid disease is influenced by a network of extra- and intracranial collaterals. The purpose of this study was to compare the findings of regional cerebral perfusion reserve (rCPR) with angiographically proven collateral circulation. In 41 patients (28 men, 13 women, age 63 ± 10 years) with angiographically proven carotid stenoses or occlusions (30 stenoses, 11 occlusions) 24 ^{99 m}Tc-HMPAO-SPECT and 25 dynamic Xe-CT investigations were conducted, both before and after acetazolamide stimulation. rCPR was quantified as the ratio (1) of the absolute rCBF values obtained by Xe-CT and (2) of the count density measured by HMPAO-SPECT of the acetazolamide administration. A rCPR of less than 95 % in a vascular territory was classified as compromised rCPR. A recent CT examination was available in all cases. According to the angiographic findings the patients could be classified into (1) group A (n = 9) with residual carotid perfusion, (2) Group B (n = 8) with collateralization via the circle of Willis, and (3) group C (n = 24) with leptomeningeal or ophthalmic artery collateral circulation. The rCPR values were significantly different in groups B and C with both methods, Xe-CT (P = 0.0035) and HMPAO-SPECT (P = 0.0014). rCPR was decreased in 13/14 group C patients investigated with Xe-CT and in 11/14 examined with HMPAO-SPECT. All patients in group B showed normal rCPR according to Xe-CT and HMPAO-SPECT. In group A, six of seven revealed decreased rCPR on Xe-CT, while rCPR values were normal in all four group A-patients examined with HMPAO-SPECT. The cerebral hemodynamics depend on a collateralization network and not only on the degree of internal carotid artery (ICA) stenosis. A decreased CPR in a vascular territory ipsilateral to an ICA stenosis or occlusion correlates strongly with the angiographic finding of leptomeningeal or ophthalmic artery collateral circulation.      

Perfusion MRI in cerebral infarction

Purpose: To investigate the hemodynamic changes in patients with acute cerebral stroke by perfusion MRI. Materials and methods: In 12 patients with acute stroke in the territory of the middle cerebral artery, perfusion MRI was performed. Peak time, mean transit time, regional cerebral blood volume and regional cerebral blood flow were calculated in the infarction, the peri-infarction area and the contralateral hemisphere. Results: In the infarction the mean blood flow was 29 ml/100 g/min, compared to about 40 ml/100 g/min in the peri-infarction area and the contralateral hemisphere. In two patients increased cortical blood flow was found in the infarction due to luxury perfusion. The cerebral blood volume was reduced in the infarction, but significantly increased, to 7.3 ml/100 g, in the peri-infarction tissue. Conclusion: Perfusion MRI allows one to differentiate various patterns of perfusion disorders in patients with acute cerebral stroke. The resulting data may be helpful in describing the pathophysiologic mechanisms of compensation.      

Evaluation of an equilibrium phase free-breathing dynamic contrast-enhanced MRI prototype sequence compared to traditional breath-held MRI acquisition in liver oncology patients

IntroductionMagnetic Resonance Imaging (MRI) is a commonly used for diagnosing metastatic liver disease. When patients are unable to achieve the necessary arrested respiration required during image acquisition, image artefacts occur that affect image quality and diagnostic value. The main contribution of this study is the evaluation of a novel prototype technique that allows a specific sub-group of patients to breathe freely throughout the acquisition of dynamic contrast enhanced equilibrium phase MRI of the liver.MethodsThe study compared a traditional single phase of arrested respiration T1-weighted (T1W) fat saturated (FatSat) volumetric interpolated breath-hold sequence (VIBE) with a novel free-breathing T1W 3D Radial VIBE prototype sequence. A cohort of patients (n = 30) with known hepatic metastases who demonstrated difficulty in complying with the instructions for arrested inspiration were scanned. Both sets of data were compared for diagnostic quality using a Likert scale questionnaire by specialist Oncology Radiologists (n = 2).ResultsHigher scores for all image quality criteria, including the presence of artefact (2.6 ± 0.57; p < 0.001), lesion conspicuity (2.9 ± 0.35; p < 0.001) and visibility of intra-hepatic vessels (2.8 ± 0.37; p < 0.001) were found using the free-breathing sequence (13.5 ± 1.94; p < 0.001 t = 13.31; df 29; p < 0.001) than the breath hold phase (8.1 ± 2.06), confirmed with kappa (k-0.023; p-0.050).ConclusionsThe results demonstrated a 39.5% improvement in overall image quality using the T1W 3D Radial VIBE prototype sequence, and have the potential to improve patient experience and reduce image artefacts during MRI imaging of this sub-group of patients.     

Contrast enhancement with GD-EOB-DTPA in MR imaging of hepatocellular carcinoma in mice: A comparison with superparamagnetic iron oxide

The purpose of this study was to evaluate the ability of the new liver-specific magnetic resonance contrast agent gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) to detect hepatocellular carcinoma (HCC). Seventeen mice with 66 chemically induced HCCs underwent magnetic resonance imaging with both Gd-EOB-DTPA (30 μmol/kg) and superparamagnetic iron oxide (SPIO; 10 μmol/kg). After enhancement, lesion-to-liver contrast-to-noise ratios (CNRs) of 47 detected HCCs increased negatively from 3.7 ± 10.7 (mean ± SD) to –55.1 ± 25.8 with Gd-EOB-DTPA (P < .001) and increased positively from 10.4 ± 10.4 to 26.1 ± 16.3 with SPIO (P < .001). The improvement of CNR after administration of SPIO was less in smaller lesions (< 4 mm), whereas that after administration of Gd-EOB-DTPA was independent of lesion size. However, Gd-EOB-DTPA positively enhanced four HCCs (8.5%), both highly differentiated (grade 1) and moderately differentiated (grade 2). Gd-EOB-DTPA allows the conspicuous detection of small HCCs; however, moderately differentiated HCCs occasionally may be positively enhanced.     

CT and MRI of the middle ear

Summary High-resolution computed tomography (HRCT) provides excellent contrast between osseous structures, air and soft tissue in conjunction with high spatial resolution. Therefore, thin-section HRCT with bone window setting is the method of choice for the examination of the middle ear structures. The indications are acute and chronic inflammatory changes, cholesteatoma and tumor, the “postoperative middle ear”, and malformations. In most cases, HRCT enables differentiation between inflammatory changes, cholesteatoma, and tumor. The excellent depiction of subtle osseous details enables the identification of erosions of the ossicles or of the bony walls of the mastoid cells, of osseous defects of the tegmen, of the bony labyrinth, and of the tympanic course of the facial canal. In addition, HRCT enables excellent depiction of reconstructions of the ossicles or prosthesis of the ossicles. Although HRCT is the first method of choice, magnetic resonance imaging (MRI) may provide additional information and lead to a more accurate diagnosis in some cases. This is explained by the excellent soft tissue contrast provided by MRI. In addition, MRI offers the possibility of using various pulse sequences and the administration of IV contrast material. Therefore, MRI may allow the differentiation between inflammatory changes, cholesteatoma, and tumor in those cases in which accurate diagnosis cannot be made by HRCT. The differentiation between a meningocele or meningoencephalocele and other entities such as tumors or cholesteatoma can be established by MRI. Furthermore, MRI can accurately depict cases of labyrinthitis or of neuritis of the facial nerve or of intracranial disease caused by middle ear processes, while this is not always possible by HRCT. In summary, HRCT of the middle ear is the method of choice, but MRI may provide supplementary information in those cases in which accurate diagnosis cannot be established by HRCT.      

MR Imaging of the breast. Localization of focal breast lesions with the magnetom open at 0.2 T

Summary Purpose: To answer the following questions: whether reliable detection of lesions is possible in low-field-MRI-system (Magnetom Open 0.2 T) equipped with currently available hard- and software components in comparison to high field system (Magnetom Impact 1.0 T). Furthermore, whether localization of lesions suspect in MR-mammography can be realized in MR system of low field (Magnetom Open 0.2 T). Patients and Methods: In 11 patients, suspect lesions were diagnosed in diagnostic MR-mammography acquired with high field system (Magnetom Impact 1.0 T) and were compared to low field MR-mammographies of 0.2 T (Magnetom Open 0.2 T). In six of the 11 patients a suspect lesion was localized using wire marking. Results: All lesions considered suspect in diagnostic MR-mammography (Magnetom Impact 1.0 T) were also clearly identified in the 0.2 T system (Magnetom Open). In six cases wire marking was performed without any complications and with an accuracy of K 0.5 cm distance to the lesion. Conclusion: Although studies in the 0.2 T system clearly showed inferior SNR (34.6 vs. 83.1) and CNR (14.6 vs. 43.5) compared to studies with the high field system, all lesions considered suspect in diagnostic MR-mammography were reliably identified also in 0.2 T studies. Due to its open construction permitting permanent access to the breast and due to sufficient image quality, the Magnetom Open is suitable for interventions on the breast.      

Low dose contrast CT for transcatheter aortic valve replacement assessment: Results from the prospective SPECTACULAR study (spectral CT assessment prior to TAVR)

BackgroundComputed tomographic angiography (CTA) based planning for transcatheter aortic valve replacement (TAVR) is essential for reduction of periprocedural complications. Spectral CT based imaging provides several advantages, including better contrast/signal to noise ratio and increased soft tissue contrast, permitting better delineation of contrast filled structures at lower doses of iodinated contrast media. The aim of this prospective study was to assess the initial feasibility of a low dose iodinated contrast protocol, utilizing monoenergetic 40 keV reconstruction, using a dual-layer CT scanner (DLCT) for CTA in patients undergoing TAVR planning.Methods116 consecutive TAVR patients underwent a gated chest and a non-gated CTA of the abdomen and pelvis. 40 keV virtual monoenergetic images (VMI) were reconstructed and compared with conventional polychromatic images (CI). The proximal aorta and access vessels were scored for image quality by independent experienced cardiovascular imagers.ResultsProximal aortic image quality as assessed by signal to noise (SNR) and contrast to noise ratio (CNR), were significantly better with 40 keV VMI relative to CI (SNR 14.65 ± 7.37 vs 44.16 ± 22.39, p < 0.001; CNR 15.84 ± 9.93 vs 59.8 ± 40.83, p < 0.001). Aortic root dimensions were comparable between the two approaches with a bias towards higher measurements at 40 keV (Bland Altman). SNR and CNR in all access vessel segments at 40 keV were substantially better (p < 0.001 for all peripheral access vessel segments) with comparable image quality.Conclusion40 keV VMI with low dose contrast dose spectral imaging is feasible for comprehensive preprocedural evaluation of access vessels and measurements of aortic root dimensions in patients undergoing TAVR.