Multiple 3D inversion recovery imaging for volume T1 mapping of the heart.

In this article, a three-dimensional inversion recovery sequence was optimized with the aim of generating in vivo volume T(1) maps of the heart using a 1.5-T MR system. Acquisitions were performed before and after gadolinium diethylenetriamine penta-acetic acid (Gd-DTPA) administration in one patient with hypertrophic cardiomyopathy and in two healthy volunteers. Data were acquired with a multishot fast field echo readout using both ECG and respiratory triggers. A dedicated phantom, composed of four solutions with different T(1) values, was positioned on the subjects' thoracic region to perform patient-specific calibration. Pixel based T(1) maps were calculated with a custom Matlab(®) code. Phantom measurements showed a good accuracy of the technique and in vivo T(1) estimation of liver, skeletal muscle, myocardium, and blood resulted in good agreement with values reported in the literature. Multiple three-dimensional inversion recovery technique is a feasible and accurate method to perform T(1) volume mapping.

[Clinical indications for the use of cardiac MRI. By the SIRM Study Group on Cardiac Imaging]. / Indicazioni cliniche per l'utilizzo della cardio RM. A cura del Gruppo di lavoro della Sezione di Cardio-Radiologia della SIRM.

Cardiac magnetic resonance (CMR) is considered an useful method in the evaluation of many cardiac disorders. Based on our experience and available literature, we wrote a document as a guiding tool in the clinical use of CMR. Synthetically we describe different cardiac disorders and express for each one a classification, I to IV, depending on the significance of diagnostic information expected.

Clinical indications for cardiac computed tomography. From the Working Group of the Cardiac Radiology Section of the Italian Society of Medical Radiology (SIRM).

Cardiac computed tomography (CCT) has grown as a useful means in different clinical contexts. Technological development has progressively extended the indications for CCT while reducing the required radiation dose. Even today there is little documentation from the main international scientific societies describing the proper use and clinical indications of CCT; in particular, there are no complete guidelines. This document reflects the position of the Working Group of the Cardiac Radiology Section of the Italian Society of Radiology concerning the indications for CCT.

Extracardiac Fontan operation for complex cardiac anomalies: seven years' experience.

METHODS: Between 1988 and 1995, 60 patients with complex cardiac anomalies underwent a total extracardiac cavopulmonary connection, a combination of a bidirectional cavopulmonary anastomosis with an extracardiac conduit interposition between the inferior vena cava and pulmonary arteries, except in one patient in whom direct anastomosis was possible. In 40 patients the total extracardiac cavopulmonary connection followed preliminary bidirectional cavopulmonary anastomosis, associated with a modified Damus-Kaye-Stansel anastomosis in 16. The conduits were constructed of Dacron fabric (n = 34), homografts (n = 3), and polytetrafluoroethylene (n = 22). RESULTS: Total early failure rate was 15% (n = 9). Six patients died, and three more had conduit takedown owing to pulmonary artery stenosis and hypoplasia (n = 2) and severe atrioventricular valve regurgitation (n = 1). Two other patients required anastomosis revision owing to stricture. In a mean follow-up of 48 months (6 to 86 months) there were no late deaths (actuarial 5-year survival 88% +/- 4%); 52 of 54 patients are in New York Heart Association class I or II. Two patients required pulmonary artery balloon dilation or stent implantation, or both, after total extracardiac cavopulmonary connection. Late tachyarrhythmias were detected in four of 54 patients: two had sick sinus syndrome with flutter necessitating a pacemaker implantation and two had recurrent flutter (actuarial 5-year arrhythmia-free rate 92% +/- 4%). Conduit patency was evaluated by serial magnetic resonance imaging studies. Preliminary data showed a 17.8% +/- 7.6% mean reduction in conduit internal diameter during the first 6 months after total extracardiac cavopulmonary connection, with no progression over the next 5 years. CONCLUSION: These results demonstrate that the total extracardiac cavopulmonary connection provides good early and midterm results and may reduce the prevalence of late arrhythmias in patients undergoing the Fontan operation.

Evaluation of hematoma by MRI in follow-up of aorto-femoral bypass.

We selected a population of 20 patients with atherosclerotic disease, submitted to implantation of aorto-femoral bypass graft. These patients were studied by MRI with T1- and T2-weighted sequences (w.s.) using a 0.5 T superconductive magnet. Investigation was performed at 1 wk, 1, 3, and 6 mo after dacron implantation, to evaluate the normal evolution of hematoma and the potential development of complications. At the first week examination, hematoma presented medium signal intensity on T1 w.s. and high signal intensity on T2 w.s.; at 1 mo control the amount of hematoma was slightly reduced and we found persistence of high signal intensity on T2 w.s.; progressive reduction of size and signal intensity on T2 w.s. was noted at 3 mo control, in patients operated for peripheral vascular disease; on the other hand we found persistence of high signal intensity in T2 w.s. in patients treated for abdominal aortic aneurysms; only after 6 mo it was evident in all patients fibrotic evolution of the collection and low signal intensity in both T1 and T2 w.s. Thus, MRI study was useful in the evaluation of patency, morphology, and in detection of intraluminal thrombosis, but also in the characterization of periprosthetic hematoma.

Abdominal aortic aneurysm evaluation: comparison of US, CT, MRI, and angiography.

We studied 26 cases of abdominal aortic aneurysm with magnetic resonance imaging (MRI), computed tomography (CT), ultrasonography (US), and angiography. Data acquired were compared to those obtained at surgery. Diameter of the aneurysm was correctly defined in all cases by CT and MRI, while angiography underestimated the diameter of lesions without peripheral calcifications. Involvement of renal arteries was present in four cases and correctly diagnosed with MRI and angiography in all of them. CT did provide this information in three cases and US were not useful. Also, iliac arteries involvement was depicted by CT, MRI, and angiography in 10 out of 10 patients. Coronal sections of MRI provided comparable images to those of angiography. By comparing these different techniques we verified the good reliability of MRI as investigation tool for an accurate evaluation of aneurysms; its only limit lying in the poor capability of detecting calcifications.

MRI postoperative monitoring in patients surgically treated for aortic dissection.

In most cases, surgery of aortic dissections repairs only the ascending portion of the aorta, leaving a residual dissection in the arch and descending aorta. We studied 17 patients operated upon for type A aortic dissection. A total of 42 magnetic resonance imaging (MRI) examinations were performed, with two to five studies per patient (mean 2.47). The studies were done between 5 weeks and 47 months (mean 17.5 months) after surgery. The patients were evaluated by MRI using gated spin-echo and gradient-echo sequences on axial and oblique sagittal views, and in selected cases, coronal views. A high incidence of abnormalities was observed. Pericardial hematoma was observed in 11% of cases, aortic and branch involvement in 41%, abdominal aortic branch involvement in 47%, dilatation of native aorta in 58%, and extension of dissection in 10%. New complications were detected during follow-up in 53% of patients. MRI was helpful in the follow-up of patients operated upon for aortic dissections, owing to its noninvasiveness and multiplanarity. By means of this technique, it was possible to obtain information about the natural history of the disease, as well as information useful for subsequent treatment.

Postsurgical follow-up of aortic dissections by MRI.

Fifteen patients with surgical repair for dissecting aneurysm were examined by Magnetic Resonance Imaging (MRI), using a 0.5 T super-conductive unit. Follow-up studies were obtained at 1 to 18 months (mean 7.2) post-surgery. T1-weighted spin-echo sequences were acquired with ECG gating on axial, coronal and oblique sagittal planes. In 6 patients gated gradient rephased sequences were also employed. Residual intimal tear in the native aorta was visualized in 11 patients, together with new or progressive extention of the dissection and aneurysmatic development. Gradient rephasing sequences were useful in detecting slow flow and thrombotic deposits and in evaluating relations to aortic vessels and intimal flap. MR images provided useful information on pathology allowing a non invasive evaluation of the status of the aorta.

[Pseudoaneurysm of the superficial femoral artery diagnosed preoperatively by magnetic resonance]. / Pseudo-aneurisma dell'arteria femorale superficiale accertato preoperatoriamente con risonanza magnetica.

A case of pseudoaneurysm of the superficial femoral artery identified preoperatively by Magnetic Resonance is reported. The number of different parameters and planes covered by the technique permitted an accurate assessment of the site, extent, internal conformation and staging of the thrombotic deposits inside the pseudoaneurysm itself.

Swelling of the submandibular glands after administration of low-osmolarity contrast agent: Ultrasound findings.

Swelling of the salivary glands occurring after injection of iodine based contrast agent is a rare late adverse reaction. Only a few cases in the literature report such diagnostic findings. We present our color Doppler ultrasound findings in a case of swelling of both submandibular glands occurring after administration of iodinated contrast agent.

[Characterization of hypertrophic cardiomyopathy with magnetic resonance]. / Caratterizzazione della cardiomiopatia ipertrofica con risonanza magnetica.

We selected 15 patients with hypertrophic cardiomyopathy (HCM) and 5 with secondary myocardial hypertrophy (SMH). All patients were examined by means of Magnetic Resonance Imaging (MRI) and echocardiography. The MR study was performed with gated T1- and T2-weighted spin echo sequences and cine MRI. We correlated echocardiographic and MRI measurements and found a correlation coefficient (R) of 0.72 for apex thickness, r = 0.84 for posterior wall thickness, 0.76 for the lateral wall and 0.89 for the area at papillary level. Cine MR acquisitions showed signal loss in the systolic phase at the outflow tract in 9 obstructive HCM patients, which was consistent with echocardiographic color Doppler findings. The signal intensity of myocardial tissue was analyzed with MRI. The values were correlated with those of the skeletal muscle. We performed the paired sample t-test on T1- and T2-weighted spin echo sequences between the signal at the septum and that of the free wall in the 15 HCM patients. The analysis showed significant differences on T2-weighted sequences (p < 0.02). Unpaired t-test was performed between the 15 HCM and the 5 SMH patients; the analysis showed significant differences on both T1- (p < 0.01) and T2-weighted sequences (p < 0.04).

[Evaluation of aortic distensibility using cine-MR before and after antihypertensive treatment with calcium antagonists and ACE-inhibitors]. / Valutazione della distensibilità aortica con cine-RM prima e dopo trattamento antipertensivo con calcioantagonisti ed ACE-inibitori.

Several studies have been performed in the last years to evaluate arterial distensibility, particularly of the aorta, in hypertension and to estimate the changes of this distensibility after anti-hypertensive treatment. The aim of this study was to assess the aortic distensibility in a group of 10 patients with essential hypertension in comparison with a control group, with regard to the vascular effects of a long-term anti-hypertensive treatment with calcium-antagonists and ACE-inhibitors. All patients were studied using cine-MR imaging, a technique with several peculiarities (multiplanar scanning, intrinsic contrast, etc) that allows simple and quick assessment of the aortic vascular parameters in the ascending and descending tracts. The results of our study show the absence of a significant improvement of aortic vascular areas, and therefore of vessel distensibility, even in the presence of a complete blood pressure normalization in all patients after a 3-month treatment. These data do not confirm previous reports in this setting, based on the ultrasonographic techniques (2D and Doppler echocardiography). Two major reasons may explain our results: first, the rigorous criteria of patient enrollment that we have stated in order to avoid any influence of age and/or other pathologies; second, the ability of MR imaging to allow accurate estimation of aortic vascular parameters and to achieve an excellent intraobserver and interobserver reproducibility in comparison with other techniques. We conclude that MR imaging is the method of choice for the assessment of cardiovascular function and morphology.

[Iron accumulation in the liver of patients with thalassemia major assessed with low field strength magnetic resonance: correlation with clinico-instrumental parameters]. / Accumulo di ferro nel fegato di pazienti con talassemia major valutato mediante risonanza magnetica con bassa intensità di campo: correlazione con i parametri clinico-strumentali.

Eight transfusion dependent patients (3 women and 5 men) with thalassemia major undergoing long-term treatment with Desferoxamine were submitted to MRI, with T2* GE sequences and low field strength. The ratio between liver mean signal intensity and skeletal muscle (L/M) and the ratio between the former and subcutaneous fat (L/F) were calculated in all patients. The results were compared with those of a control group of 7 healthy volunteers (7 men). L/M and L/F ratios were separately correlated with the following parameters: patient's age, transfusion history, serum ferritin, ferritin peak and its onset, transaminases (AST and ALT) and chelation index. The latter is a complex parameter allowing the actual assessment of iron content and of the real efficacy of chelation therapy. In all patients, both the L/M and the L/F ratios decreased significantly (L/M ratio: 0.67 +/- 0.45 vs. 1.2 +/- 0.21, p < 0.02; L/F ratio: 0.39 +/- 0.15 vs. 0.84 +/- 0.11, p < 0.001) relative to the control group. No significant correlation was found between the ratios and any hematochemical parameter, except for r = 0.77 (p < 0.04) between L/F ratio and the chelation index. Our study demonstrates that MRI may play a major role in the examination of thalassemic patients even at low field strength and with GE sequences, which yield good quality images with a relatively short acquisition time. Thus, MRI can be suggested for routine liver studies thanks to its high quality depiction of the liver and to its qualitative and semiquantitative yield. The good correlation between L/F ratio and the chelation index permits MR evaluation of the efficacy of different chelation treatments.

Intraarterial portography with gadopentetate dimeglumine: improved liver-to-lesion contrast in MR imaging.

Magnetic resonance imaging during arterial portography (MRAP) was performed by the authors in a selected group of 12 patients with hepatic lesions. A low dose of gadopentetate dimeglumine (4 mL of a 0.5-mol/L solution, corresponding to a dose of 0.05-0.07 mmol/kg) was injected into the superior mesenteric artery during acquisition of breath-holding gradient-echo or rapid acquisition spin-echo images. Images were always acquired during the first passage of gadopentetate dimeglumine through the liver parenchyma. An increase in liver-to-lesion contrast was obtained with MRAP imaging (contrast-to-noise ratio = 8 +/- 1.8 vs 19 +/- 2.7). Signal intensity enhancement of the liver was high (signal-to-noise ratio = 9.48 +/- 2.42), while the lesion presented no significant enhancement (signal-to-noise ratio = 0.55 +/- 0.22). Lobar portal vein thrombosis was detected in one patient owing to lack of enhancement of the left lobe of the liver. No side effects related to administration of iodinated and paramagnetic contrast agents were observed. This new technique provides specific enhancement of liver parenchyma with improved liver-to-lesion contrast.

[Magnetic resonance: the usefulness of gradient-echo refocusing sequences in the diagnosis of aneurysms of the abdominal aorta]. / Risonanza magnetica: utilità delle sequenze gradient echo refocusing nella diagnostica degli aneurismi dell'aorta addominale.

Sixteen patients bearing aneurysms of the abdominal aorta were studied by means of a 0.5 T MR unit. Spin-echo T1-weighted sequences and gradient-echo refocusing sequences were performed. All patients were previously submitted to US; in 8 cases angio CT was performed, and in 6 patients angiography of the abdominal aorta. A comparative analysis with the US findings showed a high correlation coefficient for the maximum diameters (R = 0.93) while site and size evaluations were not accurate. A very high correlation coefficient for the maximum diameters (0.97) was found at the comparative analysis with CT findings, while in two cases an erroneous suprarenal location was described. Angiographic examination provided valuable information about renal and iliac involvement, but the maximum diameters could not be accurately assessed. Spin-echo MRI allowed good evaluation of the maximum size, of location and extent of the aneurysm, as well as of iliac involvement; this technique, however, was useless in the characterization of the thrombus. Gradient-echo refocusing sequences have proven very useful for the identification of endoluminal contours and for the correct evaluation of the thrombus. Spin-echo sequences, on the contrary, accurately assessed only 7 cases, whereas the diagnosis was uncertain in the remaining 4 patients.

[Imaging of atherosclerosis: magnetic resonance]. / Imaging nell'aterosclerosi: risonanza magnetica.

Atherosclerosis is the disease with the most important social impact in terms of cost and human life. Its study in the prevention and cure of its consequences needs integration using many imaging modalities, and magnetic resonance presents advantages due to its particular characteristics. The Authors make an overview of its indications and potential applications in the assessment of atherosclerotic disease. In vitro studies have demonstrated that it is possible to evaluate the normal and abnormal components of vessel walls by means of magnetic resonance imaging (MRI) as well as fatty deposition and intraplaque hemorrhage. On the other hand, in the in vivo studies, despite the impossibility to make a too fine structural analysis of the vessel wall, MRI allows to easily discriminate between blood flow and parietal wall. This is of great importance in the study concerning arterial aneurysms, that represent a consequence of atherosclerotic disease. Information as the presence, the site, the extension, the collateral vessel involvement and, finally, the presence or absence of dissection are all obtainable by using MRI. In the early 1990's magnetic resonance angiography (MRA) was developed and is now used in clinical practice. By means of this new application of MRI there is the possibility of increasing the non invasive screening of atherosclerosis especially in some body districts. The evaluation of the plaque obtainable by the combined use of MRA and ultrasound studies allows to decrease the employment of traditional and digital angiography. If, as studies predict, we will able to obtain coronary angiograms in the near future, there will be a further increase in the non invasive evaluation and in the prevention of atherosclerotic disease.

[Abdominal aortic aneurysms. Comparison of magnetic resonance, ultrasound, CT x-ray and angiography]. / Aneurismi aortici addominali. Risonanza magnetica a confronto con US, TC ed angiografia.

Twenty-four cases of abdominal aortic aneurysm were studied by means of MR Imaging, Computed Tomography (CT), Ultrasound (US) and Angiography. MR Imaging gave detailed information on the site and extension of the aneurysm. The extent of branches involvement, the presence of thrombosis, and the adjacent structures were also demonstrated. Major limitations of angiography were its morbility, and the difficult/impossible demonstration of eventual thrombi, and of the adjacent structures. CT, although extremely valuable in emergency cases and in the detection of calcifications, provided insufficient information on the involvement of the vessels originating from the aorta. US proved useful in the screening of abdominal aortic aneurysms, but lacked both the accuracy and the reliability necessary to a complete preoperative evaluation. MR Imaging proves thus to be a good investigation technique for a complete assessment of aneurysmatic lesions. Its major limitation is its inability to detect calcifications, while its major advantages are the accurate demonstration of both blood flow and eventual thrombi, and the multiplanarity and non-invasiveness of the methodology.