Cardiac hydatid cyst in a child.

Cardiac hydatid cyst is a rare disease, especially in children. An 11-year-old boy with a previous anaphylactic reaction and episodes of abdominal pain was admitted for workup of an acquired long systolic murmur. Echocardiographic investigation disclosed a tumor of the right ventricular anterior wall, with multiple loculations. Magnetic resonance imaging characterized it as a multilobular tumor with cyst formation and disclosed another cyst in the right pulmonary artery. With a positive ELISA reaction the child was admitted for surgery with the diagnosis of cardiac and pulmonary hydatid cysts. Cardiac surgery was performed with good results, followed by medical treatment with albendazole.

[Broncho-splenic fistula caused by hydatidosis]. / Fistula bronco-esplénica devida a hidatidose.

To our knowledge, this is the first case report of a broncho-splenic fistula of hydatid origin. We discuss the clinical, radiological and therapeutic aspects of this rare complication of hydatid disease.

Normal and diffusely abnormal myocardium in humans: functional and metabolic characterization with P-31 MR spectroscopy and cine MR imaging.

The current study tested the concept that cine magnetic resonance (MR) imaging and phosphorus-31 MR spectroscopy might be used to provide a comprehensive evaluation of the functional and metabolic status of the myocardium in humans. Thirteen patients with congestive cardiomyopathy and eight healthy volunteers were imaged at 1.5 T with the one-dimensional chemical shift imaging technique for localization of P-31 MR spectroscopy and an electrocardiographically referenced gradient refocused sequence for imaging of the heart. Prominent peaks in the PDE and PME regions were observed in cardiomyopathic patients, but only the former peak was measured. The PCr/beta-ATP peak ratio was not significantly lower in cardiomyopathic patients compared with healthy subjects (1.51 +/- 0.08 vs 1.54 +/- 0.04). The ratios of PDE/PCr (0.80 +/- 0.07 vs 0.54 +/- 0.10) (P less than or equal to .01) and PDE/beta-ATP (1.19 +/- 0.10 vs 0.84 +/- 0.08) (P less than or equal to .05) were significantly higher in patients with dilated cardiomyopathy compared with healthy volunteers. Left ventricular systolic wall thickening was significantly lower and left ventricular peak and end-systolic wall stress and mass were significantly higher in cardiomyopathic patients compared with healthy volunteers. Thus, localized, gated P-31 MR spectroscopy combined with cine MR imaging allowed identification of both abnormal myocardial phosphate metabolism and abnormal ventricular function. While this study suggests that increased myocardial PDEs may be a marker for abnormal myocardium, the sensitivity and specificity of this marker need to be further evaluated.

MR imaging of bladder neoplasms: correlation with pathologic staging.

This retrospective study describes the accuracy of magnetic resonance (MR) imaging in determination of local disease extent in 34 examinations performed for evaluation of primary or recurrent bladder carcinoma. The 34 examinations were carried out in 29 patients (17 men, 12 women, aged 34-89 years). All studies were followed within 30 days by surgical and pathologic evaluation. Images were interpreted by two radiologists unaware of clinical or pathologic findings. MR imaging staging conformed to the TNM system of the International Union Against Cancer (IUAC). Pathologic evaluation showed bladder neoplasms in all cases; three patients' pathologic specimens contained two or more histologic types of tumors. MR imaging staging of the depth of tumor invasion was correct in 85% of examinations. Sensitivity of MR imaging for detection of deep muscle invasion was 97%, specificity 83%, and accuracy 94%. Sensitivity of MR imaging for detection of extravesical tumor extension was 95%, specificity 100%, and accuracy 97%. Sensitivity for detection of pelvic lymph node metastases was 50%, specificity 100%, and accuracy 82%. Our population included many patients with locally advanced disease. This pattern reflects standards of clinical practice by which superficial lesions are staged and resected endoscopically, and deeply invasive tumors are imaged prior to radical surgery.

MR signal intensity of parathyroid adenomas: correlation with histopathology.

Recent experience has shown that parathyroid adenomas vary in their MR signal intensity, which raises the question of whether the signal intensity is related to different histologic characteristics. In order to address this question, 10 patients who had MR imaging studies (four at 0.35 T, six at 1.5 T) showing large- to medium-sized parathyroid adenomas and who subsequently underwent surgery with histologic proof of the lesion were evaluated. The MR appearance was compared with histologic characteristics. The adenomas were classified into three groups according to the MR appearance: group I, low signal intensity on short TR/TE images, high signal intensity on long TR/TE images (n = 5); group II, low signal intensity on short and long TR/TE images (n = 3); group III, high signal intensity on short and long TR/TE images (n = 2). Histologic analysis revealed that the major features of each group were different. High cellularity without degeneration or fibrosis was observed for all five adenomas from group I. In group II, all three adenomas showed cellular degenerative changes, old hemorrhage with hemosiderin-loaded macrophages, and/or fibrosis. In group III, both adenomas showed evidence of acute hemorrhage without significant degenerative or fibrotic changes. These data suggest that the signal intensity of parathyroid adenomas on T1- and T2-weighted images corresponds at least in part to differences in histologic composition.

Incorporation versus infection of retroperitoneal aortic grafts: MR imaging features.

The magnetic resonance (MR) imaging characteristics of normal aortic graft healing were compared with those of perigraft infection in 57 patients after aortic graft implantation. Thirty-three patients without postoperative complications underwent MR imaging in a 0.35-T unit 1 week after graft implantation, and 13 of those patients were reexamined 2-3 months after graft implantation. Twenty-four patients with clinically suspected perigraft infection underwent MR imaging 6 weeks to 18 years after graft implantation. Early normal postoperative changes were characterized by a perigraft collar of low to medium signal intensity on T1-weighted images and of high intensity on T2-weighted images in all 33 cases, consistent with perigraft fluid collection. In 10 of 13 patients reexamined 2-3 months postoperatively, the MR images demonstrated a collar of tissue consistent with perigraft fibrosis. In cases of clinical suspicion of retroperitoneal graft infection, MR imaging showed eccentric fluid collections of low to medium signal intensity on T1-weighted images and high intensity on T2-weighted images at more than 3 months after surgery. The MR findings were diagnostic of retroperitoneal perigraft infection in 17 of 20 patients shown to be infected at surgery. Retroperitoneal infection was correctly excluded on the basis of MR findings in four patients. Thus, MR imaging is an accurate imaging method for the diagnosis of aortic graft infection. In the early postoperative phase, resolving perigraft fluid cannot be differentiated from perigraft infection.

Use of radio-frequency field gradients to image blood flow and perfusion in vivo.

A magnetic resonance imaging method based on the use of radio-frequency (RF) magnetic field gradients to detect molecular motion has been combined with GRASS (gradient-recalled acquisition in a steady state) imaging to detect arterial blood flow in vivo. The method has been used to selectively attenuate signals from flowing blood in the human finger. Attenuation of signals from arterial blood was greatly reduced when blood flow was decreased with the application of a tourniquet. This result demonstrated the sensitivity of the technique to the rate of blood flow. RF gradient coils can be used to generate very high RF gradients with submicrosecond rise times and minimal eddy currents. Therefore, this method may prove useful for imaging very slow, nonuniform flow through capillary beds and in the extravascular space.

Malignant versus nonmalignant retroperitoneal fibrosis: differentiation with MR imaging.

To evaluate the features on magnetic resonance (MR) images of malignant and nonmalignant retroperitoneal fibrosis (RPF) and to assess the usefulness of MR imaging in differentiating the two conditions, MR studies of nine patients with malignant RPF were retrospectively examined and compared with those of eight patients with nonmalignant RPF. Morphologic findings at MR imaging were similar for both conditions. The lesions were, however, heterogeneous in six of the nine patients with malignant RPF and homogeneous in all eight patients with nonmalignant RPF. On T2-predominant images, malignant RPF showed high signal intensity, while nonmalignant RPF showed low signal intensity. On T2-predominant images, signal intensity and T2 were significantly higher in malignant RPF than in nonmalignant RPF. Differentiation between malignant and nonmalignant RPF appears feasible and depends on tissue contrast rather than on morphologic characteristics.

Regulation of hepatic inorganic phosphate and ATP in response to fructose loading: an in vivo 31P-NMR study.

Fructose loading results in hepatic accumulation of fructose 1-phosphate (Fru1 P). The goals of the present experiments were: first, to distinguish between ATP, intracellular inorganic phosphate (Pi), and extracellular Pi as sources of phosphate for the phosphorylation of fructose, and second, to examine the influence of ATP and Fru1 P on movement of phosphate into and out of these three pools. To achieve these goals, 31P-NMR was used to monitor the response of hepatic ATP, Pi and Fru1 P to two consecutive injections of fructose. The first was administered with ATP at the control level, and the second, 1 h after the first, with ATP at 65% of the control level. Changes in intra- and extracellular Pi were distinguished by correlating measurements of total NMR-detectable phosphorus and NMR-detectable Pi with measurements of plasma Pi. The initial fructose injection resulted in rapid accumulation of Fru1 P, small decreases in plasma and NMR-detectable Pi and a dramatic decrease in ATP. Total NMR-detectable phosphorus did not change, suggesting that phosphate did not enter or leave the liver. Therefore, accumulation of Fru1 P was initially balanced by an equivalent decrease in ATP, without large changes in Pi. Following the second injection, when ATP was at 65% of control. Fru1 P accumulated at approximately the same rate and to the same level as achieved following the first injection. There was little further change in ATP and a marked decrease in NMR-detectable Pi, while plasma Pi was higher than after the first injection. Therefore the greater decrease in NMR-detectable Pi following the second injection represented a significant decrease in intracellular Pi. Return of Fru1 P to control coincided with a dramatic increase in plasma Pi, and a decrease in total NMR-detectable phosphate. This suggests that phosphate released from Fru1 P entered the extracellular space. These data suggest the mechanisms by which intracellular Pi is regulated. When sufficient ATP is available, ATP hydrolysis supplies phosphate for the synthesis of Fru1 P, and prevents a significant decrease in intracellular Pi. When ATP is reduced, accumulation of Fru1 P depletes intracellular Pi. Therefore, decreased availability of ATP correlates with increased utilization of intracellular Pi. When Fru1 P returns to control, the increase in intracellular Pi is limited by release of Pi into the plasma.

Detection of thrombus by using phase-image MR scans: ROC curve analysis.

Spin-echo phase images have been shown to be sensitive to blood flow and have been used to differentiate slow flow from thrombus, with an apparent advantage in comparison with spin-echo intensity images alone. In order to quantify the diagnostic efficacy of phase images, a study was performed comparing the sensitivity and specificity of MR imaging in identifying intravascular thrombus using spin-echo magnitude images alone and combined with phase images. In 45 subjects, 66 vessels with questionable intraluminal signal were reviewed in a blinded manner by four radiologists using seven levels of certitude for the diagnosis of thrombus. Vessels in the thorax, abdomen, and pelvis were included in the evaluation and were selected on the basis of the presence of intraluminal signal, which raised the possibility of intravascular disease. Corroborative studies were available in all cases. Receiver-operator-characteristic curves were constructed for the accuracy of the decision of intraluminal thrombus vs flow signal when using magnitude images alone and when using magnitude plus phase images. Magnitude images identified thrombus with a sensitivity of 35% at a specificity of 90%. On the other hand, combining magnitude image and phase images yielded sensitivities of 85% and 83% at specificities of 90% and 95%, respectively. We conclude that addition of phase images substantially increases the level of confidence in detecting intravascular thrombosis.

A 31P NMR study of the GI tract: effect of fructose loading and measurement of transverse relaxation times.

The effect of fructose loading on high-energy phosphates in the jejunum, ileum, and large intestine of rats was studied using 31P NMR. Following fructose loading, an increase in the intensity of the PME resonance was observed in the jejunum, indicating an accumulation of fructose-1-phosphate. There were no significant changes in ATP or Pi. This demonstrates that the activity of fructokinase in the jejunum can be monitored by 31P NMR. Fructose loading had no detectable effect on metabolite levels in the ileum and large intestine. Resolution of intestinal spectra was poor due to unusually large linewidths and the presence of broad underlying signals. To study the mechanism of line broadening, the T2's of the phosphorus resonances were measured using a solenoidal coil. The T2's of the ATP, Pi, PME, and PCr resonances were much longer than the T2's, suggesting that the linewidths of these resonances are primarily due to susceptibility gradients and/or compartmentation of metabolites. Other signals, particularly in the PDE region, were homogeneously broadened and had very short T2's. Spin echoes obtained with evolution times of 1 to 4 ms suppressed these broad components, with little loss of intensity in the inhomogeneously broadened resonances; as a result, resolution was improved.