Michael M. Ambrosino

Comparison between in-phase and opposed-phase T1-weighted breath-hold FLASH sequences for hepatic imaging

PURPOSE Our goal was to compare in-phase (IP) and opposed-phase (OP) sequences for GRE breath-hold hepatic imaging. METHOD Non-contrast-enhanced IP and OP GRE breath-hold images were obtained in 104 consecutive patients referred for abdominal MRI at 1.0 T. For both sequences, the TR, FA, matrix, FOV, slice thickness, interslice gap, and measurements were kept constant. Images were compared quantitatively [liver/spleen and liver/lesion signal difference/noise ratio, (SD/N)] and qualitatively (artifacts, lesion detection and conspicuity, and intrahepatic anatomy). RESULTS There was no statistically significant difference when comparing IP and OP sequences for liver/spleen and liver/lesion SD/N or for the qualitative parameters. In patients with fatty infiltration, the OP sequences yielded substantially lower values for liver/spleen and liver/lesion SD/N (0.9 and -1.2, respectively) than the IP sequences (20 and 17, respectively). Furthermore, in several cases with fatty infiltration, many more lesions were identified using IP images. CONCLUSION The use of IP and OP GRE sequences provides complementary diagnostic information. Focal liver lesions may be obscured in the setting of fatty infiltration if only OP sequences are employed. A complete assessment of the liver with MR should include both IP and OP imaging.

Gadolinium-enhanced 3D MRA of the aortic arch vessels in the detection of atherosclerotic cerebrovascular occlusive disease

PURPOSE Our goal was to evaluate non-breath-hold Gd-enhanced 3D MR angiography (MRA) for the detection of atherosclerotic occlusive disease of the aortic arch vessels and to compare image quality with two breath-hold techniques. METHOD One hundred sixty consecutive patients with known or clinically suspected atherosclerotic cerebrovascular occlusive disease underwent Gd-enhanced 3D MRA of the aortic arch and great vessels. One hundred twenty-six examinations were performed with the body coil after infusion of 40 ml of Gd-DTPA; 89 of these were performed without breath-holding and 37 were acquired during suspended respiration. Thirty-four examinations were performed in a body phased-array coil with breath-holding, a timing examination, and 20 ml of contrast agent by manual (n = 17) or power (n = 17) injection. Images were evaluated for the presence of blurring and ghosting artifacts and venous enhancement. Of the 27 patients who underwent non-breath-hold MRI and digital subtraction angiography (DSA), two readers blinded to the DSA results retrospectively evaluated the MRA examinations for the presence of occlusive disease of the innominate, carotid, subclavian, and vertebral arteries. DSA correlation was not evaluated for the 71 breath-hold studies. RESULTS Sensitivity and specificity for arch vessel occlusive disease with non-breath-hold MRA were 38 and 94% for Reader A and 38 and 95% for Reader B. Breath-holding significantly reduced blurring and ghosting artifacts (p < 0.001) when compared with non-breath-hold imaging, and use of 20 ml of contrast medium, with a timing examination, resulted in significantly less venous enhancement than seen with 40 ml (p < 0.001). CONCLUSION Non-breath-hold Gd-enhanced 3D MRA is insensitive for detecting arch vessel occlusive disease. Breath-hold imaging, in conjunction with a timing examination and a lower dose of contrast agent, improves image quality, but further studies are needed to assess diagnostic accuracy.

Monitoring of girls undergoing medical therapy for isosexual precocious puberty

We evaluated the use of sonography in monitoring the efficacy of suppressive therapy with a gonadotropin releasing hormone analogue in girls being treated for isosexual precocious puberty. Ten girls 5 to 9 years of age underwent serial sonography and hormonal stimulation tests on the same day. Sonographic trends of decreasing ovarian volume and uterine length indicated early suppression even when absolute values were above threshold. Changes in ovarian volume were the most sensitive predictor of pituitary‐gonadal suppression. Sonography is a sensitive and accurate method of monitoring medical therapy; ovarian volume and analysis of interval change are the most sensitive barometers of change.

Brain tumors in infants less than a year of age

A retrospective examination of brain tumors in infants less than a year of age was undertaken by reviewing their charts and CT scans. In contradistinction to brain tumors found in older children, most tumors were supratentorial in location. The most common histologic types included: astrocytoma, ganglioglioma and primative neuroectodermal tumors. Apart from their larger size at the time of presentation, these tumors were radiologically and pathologically similar to analogous tumors found in adults.

The syndrome of achalasia of the esophagus, ACTH insensitivity and alacrima

A 7-year-old male presented with a triple A syndrome, a tirad of ACTH insensitivity, achilasia and alacrima. His clinical course is followed and the literature reviewed.

The antral nipple sign of pyloric mucosal prolapse: endoscopic correlation of a new sonographic observation in patients with pyloric stenosis.

This study describes the antral nipple sign of pyloric mucosal prolapse, a newly delineated sonographic observation in patients with pyloric stenosis, correlates the endoscopic findings, and examines its prevalence and significance in 31 consecutive patients with pyloric stenosis. Fifty patients who did not have pyloric stenosis served as the control population. The antral nipple sign consists of visualization of prolapsed, hypertrophied pyloric mucosa protruding into the gastric antrum. Using the Wilcoxon scores (rank sums), there was no significant difference among the patients in age, weight, or pyloric muscle dimensions. Although the diagnosis of pyloric stenosis is made on the basis of muscle thickness, we have documented that the pyloric mucosa becomes redundant in infants with pyloric stenosis, permitting a fuller understanding of the anatomic correlate underlying the sonographic images.

Sonographic diagnosis of intramural duodenal hematoma.

Intramural duodenal hematoma, sometimes accompanied by retroperitoneal extension, is a frequent injury resulting from blunt abdominal trauma in childhood. In fact, it may be the first sign of child abuse identified in the young child. The typical appearance of this injury on upper gastrointestinal examination was described by Felson, 1 although its radiographic variability has been stressed more recently.2 We have encountered two cases of intramural duodenal hematoma diagnosed with sonography. In the appropriate clinical setting, this diagnosis may be made sonographically with specificity using state-of-the-art equipment and technique. Computerized tomography (CT} and barium meal (UGI} studies were done in these cases and the multimodality appearance of the injury is discussed.

Congenital pulmonary steal associated with Tetralogy of Fallot, right aortic arch and an isolated left carotid artery

In patients with Tetralogy of Fallot, collateral supply to the pulmonaryartery from systemic arterial sources is fequently encountered. However, collateral blood flow arising from the cerebral circulation has, to our knowledge, not been reported in this condition. We describe a patient with Tetralogy of Fallot in whom the left pulmonary artery filled directly via retrograde flow from the left carotid artery. Review of the literature in search of a similar case was unrevealing. A theoretical embryologic basis for this anomaly is discussed.

Pediatric hepatic CT: an injection protocol

Objective. To determine an injection protocol for pediatric hepatic CT and to investigate the use of power injection.Materials and methods. Eighty-seven studies were prospectively performed using ioversol (320 mg iodine per cc) at 2 cc/kg. Three techniques were used: helical (1 s/slice); dynamic, non-breath-hold (5.5 s/slice); dynamic, breath-hold (10 s/slice) scans. The liver-scan time for each study was determined. Scan initiation ranged from 25 to 80 s. An injection duration (50–100 seconds) was selected. From the contrast volume (2 cc/kg × kg body wt) and injection duration, the injection rate (cc/s) was calculated for each patient. Each study was grouped by injection rate corrected for body weight (cc/kg/min) into: 1.2–1.5, 1.51–2.0, and 2.01–2.4. The aortic/liver attenuation curves were plotted for each group.Results. Liver-scan time for helical studies was a mean of 26 s, for dynamic, non-breath-hold studies 75 s, dynamic breath-hold scans were 154 s. Injection rates of 1.2–1.5 cc/kg/min produced a scanning interval of 165 s. Injection rates of 1.51–2.0 cc/kg/min produced a scanning interval of 120 s. Injection rates of 2.01–2.4 cc/kg/min produced a scanning interval of 90 s. There was no increase in hepatic attenuation for the injection rates 2.01–2.4 cc/kg/min compared with 1.51–2.0 cc/kg/min. There was one complication related to injection through a central line.Conclusions. An injection protocol was determined for helical studies with injection rates of 1.7–2.0 cc/kg/min with initiation at 60 s; for dynamic, non-breath-hold studies with injection rates of 1.5–1.7 cc/kg/min with initiation at 50 s; and for dynamic breath-hold studies with injection rates of 1.2–1.5 cc/kg/min with initiation at 45 s. Power injection was used safely in our population.

MR findings in Shone's complex of left heart obstructive lesions.

Background. Shones complex is a series of four obstructive or potentially obstructive left-sided cardiac lesions (supravalvular mitral ring, parachute deformity of the mitral value, subaortic stenosis, and coarctation of the aorta). Both the complete form (all four lesions) and incomplete forms (less than four lesions) have been described. Objective. To determine which abnormalities of Shones complex could be characterized by MR. Materials and methods. MR examinations in three patients (one complete, two incomplete) were retrospectively reviewed. Results. A supravalvular mitral ring, found at surgery in one patient, was not identified. Regurgitant and stenotic flow across the mitral valve, abnormal motion of the valve leaflets and abnormalities of the papillary muscles were identified. Individual chordal attachments were difficult to resolve. Narrowing in the subaortic region and abnormal flow from the subaortic region through the valve plane were demonstrated. A discrete subaortic diaphragm in one patient was not resolved. Both focal and diffuse types of coarctation of the aorta were well characterized. Conclusion. MR imaging is suited to evaluation of patients with Shones complex. Individual chordal attachments and thin diaphragms of the mitral and aortic valves were difficult to resolve.