Musculoskeletal ultrasound: an update.

In summary, musculoskeletal sonography is a rapidly growing field of interest around the world. Outside of America, it is often the first and definitive imaging modality fordisorders of the musculoskeletal system. Musculoskeletal ultrasound offers rapid, inexpensive, real-time examination of the structures of interest with easy comparison to the contralateral side. Principles of one area of musculoskeletal sonography easily generalize to other areas.

Utility of magnetization prepared GRE MRI for the detection of focal liver lesions.

We compared the efficacy of rapidly acquired magnetization prepared gradient-echo (MP-GRE) sequences with CT and standard MRI pulse sequences for the detection of focal liver lesions. Fourteen patients with 28 focal liver lesions were scanned. TI times of 300, 450, and 600 ms were used. MP-GRE lesion conspicuity was compared to corresponding CT, T1, T2, T2-post-superparamagnetic-iron-oxide (SPIO), and STIR images. It was found that the differences between MP-GRE and CT and MP-GRE and T1 MRI were not significant. However, overall anatomic detail was better with CT and T1 MRI than MP-GRE. Lesion conspicuity was significantly worse with the MP-GRE than with the T2, T2-post-SPIO, and STIR sequences (all p values = 0.00). Maximal liver signal nulling occurred at TI = 300 ms in 13 out of 14 patients. However, the T1 for optimal focal liver lesion conspicuity varied widely and could not be predicted before scanning. No new lesions were seen on the MP-GRE sequence that could not be seen on the CT or standard MRI sequences. As currently implemented, MP-GRE imaging offers no advantage in the detection of focal liver lesions over CT and standard MRI pulse sequences.

Automatic fetal head measurements from sonographic images.

RATIONALE AND OBJECTIVES: We designed an image processing technique to automatically measure the biparietal diameter (BPD) and head circumference (HC) from prenatal sonograms. We evaluated the performance of the algorithm by comparing the resulting measurements with those made by experienced sonographers. METHODS: Thirty-five digitized sonograms of the fetal head were obtained during routine imaging. The BPD and HC were automatically computed by detecting the inner and outer boundaries of the fetal skull using the computer vision technique known as the "active contour model." Six experienced sonographers also measured the BPD and HC on these images. RESULTS: The algorithm failed to locate the boundaries in two of the 35 cases. For the remaining cases, the mean absolute difference between the automated measurements and the average of the six observers was 1.4% for BPD and 2.9% for HC. The correlations were .999 for the BPD and .994 for the HC. The computer's measurements were no different from the six observers' measurements than the observers' measurements were from one another. CONCLUSION: The tested algorithm effectively and accurately measures BPD and HC automatically. We are currently in the process of integrating this algorithm into an ultrasound machine.

CT angiography of the visceral vessels.

CT angiography (CTA) is a promising new technique for vascular imaging. This review focuses first on the technique necessary for successful scanning of the visceral vessels. As in many new modalities, there are different protocols for scanning and rendering of images. The relative strengths and weaknesses of these different approaches are discussed. A discussion of the applications of CTA to depict normal and abnormal anatomy of the visceral vessels follows. These applications include celiac stenosis, splenic artery aneurysms, evaluation for hepatic arterial anatomy before liver transplantation, visceral arterial anatomy in pancreaticoduodenal surgery, the superior mesenteric artery in intestinal ischemia, vascular encasement in patients with pancreatic neoplasms, and, finally, the hepatic vessels before hepatic tumor resection.

MR angiography of the portal venous system.

MR angiography (MRA) has become an increasingly important and practical clinical tool for the noninvasive assessment of abdominal vessels. Both two-dimensional time-of-flight and phase contrast techniques allow accurate evaluation of the portal venous system. This article reviews these two MRA techniques and discusses their impact on the diagnosis of vascular abnormalities of the portal venous system.

MR angiography of the peripheral vasculature.

MR angiography (MRA) for the evaluation of peripheral arterial occlusive disease is a rapidly evolving technique. Recent prospective clinical trials have indicated that MRA may play an important role in the evaluation of patients with peripheral arterial disease. This article discusses the pertinent technical aspects and limitations of peripheral MRA as well as some of the clinical data available.

Programmable ultrasound imaging using multimedia technologies: a next-generation ultrasound machine.

High computational and throughput requirements in modern ultrasound machines have restricted their internal design to algorithm-specific hardware with limited programmability. We have architected a programmable ultrasound processing system, Programmable Ultrasound Image Processor (PUIP), to facilitate engineering and clinical ultrasound innovations. Multiple high-performance multimedia processors were used to provide a computing power of 4 billion operations per second. Flexibility was achieved by making our system programmable and multimodal, e.g., B-mode, color flow, cine and Doppler data can be processed. We have successfully designed and implemented the PUIP to fit within an ultrasound machine. It provides a platform for rapid testing of new concepts in ultrasound processing and enables software upgrades for future technologies. Current and future clinical applications include extended fields of view, quantitative measurements, three-dimensional ultrasound reconstruction and visualization, adaptive persistence, speckle reduction, edge enhancement, image segmentation, and motion analysis. The PUIP is a significant step in the evolution of ultrasound machines toward more flexible and generalized systems bridging the gap between many innovative ideas and their clinical use in ultrasound machines.

Low-attenuation oral GI contrast agents in abdominal-pelvic computed tomography.

BACKGROUND: We designed and evaluated a low-attenuation oral contrast agent for abdominal-pelvic computed tomography (CT). METHODS: In vitro studies, were performed initially to evaluate the imaging characteristics of multiple solutions. These studies resulted in two solutions being compared with the presently accepted oral CT agents of dilute iodinated contrast and water. Ninety-eight consecutive subjects already scheduled for routine outpatient abdominal-pelvic CT were enrolled. Subjects were randomized to water (n = 30), fiber solution (n = 32), polyethylene glycol (PEG; n = 11), or dilute iodinated solution (DI; n = 25). Examinations were then evaluated for gastric distention, small bowel distention, small bowel wall visualization, and colonic transit. A questionnaire was given to the study subjects for feedback concerning taste and potential side effects from these agents. RESULTS: PEG tended to provide better bowel distention, wall visualization, and colonic transit compared with water, fiber solution, and DI. Areas of statistical significance included: (1) average bowel diameter in the left upper quadrant for water was 17.50 mm, whereas that for PEG was 21.88 mm (p < 0.05); (2) average bowel diameter in the pelvis for water was 14.79 mm, that for fiber was 15.67 mm, and that for PEG was 18.48 mm (p < 0.05); (3) wall visualization was better with PEG than with fiber (p < 0.05); (4) successful transit of contrast to the colon occurred in every subject who received PEG compared with only 20% of those received water and 39% of those who received fiber (p < 0.05). Similar trends for the superiority of PEG over DI were noted, although many of these did not reach statistical significance. CONCLUSION: PEG solution has imaging characteristics related to bowel wall visualization, luminal distention, and colonic transit that make it an effective oral agent for abdominal pelvic CT examination.

Hepatic teratoma in an adult. Case report with a review of the literature.

Teratomas of the liver in adults are rare. We believe this to be only the fifth such case reported, the first with CT correlation and with plain film documentation of the development and slow progression of the lesion from age 44 to 61. A review of the literature regarding hepatic teratomas is appended.

The measurement of the kinetics of lipid phase transitions: a volume-perturbation kinetic calorimeter.

A volume-perturbation kinetic calorimeter to be used to study membrane phase transitions in lipid vesicles has been developed. In this instrument, the voltage-dependent extension of a stack of piezoelectric crystals is used to force the solution being studied to undergo a small adiabatic bidirectional volume change. This volume change induces a shift in the equilibrium position of the lipid gel to liquid-crystalline transition. The time course of the relaxation to the new equilibrium position is then monitored by observing the induced temperature and pressure changes as a function of time.

Helical CT during arterial portography: optimization of contrast enhancement and scanning parameters.

PURPOSE: To determine the optimal scanning parameters for helical computed tomography during arterial portography (CTAP) of the liver. MATERIALS AND METHODS: Single- and double-helix CTAP were performed in 11 and 20 adult patients, respectively, with 200 mL of contrast material (300 mg of iodine per milliliter) injected at a rate of 3 mL/sec via the superior mesenteric artery. Scanning delays were adjusted for single-helix CTAP so the last scan was obtained at 66 seconds. Delays were adjusted for double-helix CTAP so the last scan during the first helix (CTAP-1) was obtained 10 seconds before the end of the injection at 56 seconds and the first scan during the second helix (CTAP-2) was obtained at the end of the injection at 66 seconds. RESULTS: Single-helix CTAP scans were of poor quality owing to multiple perfusion abnormalities. Lesion detection for double-helix CTAP-1 was 93.2% and was 100% for CTAP-2, and CTAP-2 scans had significantly fewer perfusion abnormalities. CONCLUSION: A scanning delay of 60-66 seconds appears to be optimal. The CTAP-1 scans showed no useful information and need not be acquired.

Iliac angle as a marker for Down syndrome in second-trimester fetuses: CT measurement.

PURPOSE: To determine if the iliac angle is greater in second-trimester fetuses with trisomy 21 than in euploid fetuses and to establish the best level and plane for measuring this angle by using three-dimensional computed tomography (CT). MATERIALS AND METHODS: CT was performed in 18 formalin-preserved fetuses (eight trisomy 21, 10 euploid control fetuses), and the pelvic bone anatomy was reconstructed three-dimensionally. Iliac angles were measured in axial views at three levels in two planes. Data were analyzed nonparametrically with the Mann-Whitney test. RESULTS: The mean gestational ages for trisomy 21 and control fetuses were 17.0 and 16.7 weeks, respectively. The external plane was the easiest to measure and the most reproducible. The mean iliac angles were significantly greater (P < .05) in the trisomy 21 fetuses than in the control fetuses and were as follows: superior level, 95.6 degrees vs 76.4 degrees; middle level, 84.5 degrees vs 62.5 degrees; and lower level, 78.1 degrees vs 57.5 degrees. With a 90 degrees threshold, the superior iliac angle measurement had a sensitivity of 75%, a specificity of 89%, and an odds ratio of 24 for Down syndrome. CONCLUSION: Second-trimester fetuses with trisomy 21 have a significantly greater iliac angle than euploid fetuses have. The iliac angle varies with the axial level, with the widest angle at the most superior level. Measurement of the iliac angle at the most superior level is supported as a potential marker for Down syndrome at prenatal ultrasonography.

Normal adult epididymis: evaluation with color Doppler US.

PURPOSE: To reevaluate blood flow patterns in the normal epididymis with color Doppler sonography. MATERIALS AND METHODS: Twenty-seven healthy volunteers (aged 19-68 years) with no history of scrotal disease, infection, or surgery (including vasectomy) underwent gray-scale imaging, color Doppler imaging, and pulsed Doppler spectral analysis of the head, body, and tail of each epididymis. All volunteers had negative results of urinalysis. RESULTS: In each of the 54 epididymides, blood flow was detected with pulsed Doppler and color Doppler imaging 100% of the time in the head, body, and tail. The mean resistive indexes for the right epididymal head, body, and tail were 0.55, 0.55, and 0.58, respectively. Similar values for the left side were 0.54, 0.55, and 0.55, respectively. None of these values were statistically significantly different. CONCLUSION: With current ultrasound imaging technology, epididymal flow was demonstrated not only in the head but also in the body and tail of the epididymides of all of our healthy volunteers. Thus, detection of flow in the epididymis at color Doppler imaging can be a normal finding and does not necessarily imply epididymitis.

The "genetic sonogram": comparison of the index scoring system with the age-adjusted US risk assessment.

PURPOSE: To compare two ultrasonographic (US) methods for prenatal detection of fetal Down syndrome. MATERIALS AND METHODS: Genetic amniocentesis was successfully performed in 3,303 consecutive women with high-risk pregnancies (mean gestational age, 17.1 weeks). All patients underwent a complete "genetic US" examination prospectively. Risk was assessed by using (a) various modifications of the index scoring system (ISS) and (b) the age-adjusted US risk assessment (AAURA). RESULTS: The prevalence of Down syndrome in this population was 1.6% (53 of 3,303). By using a threshold of at least 2 points to detect trisomy 21, the best ISS had a sensitivity of 45.3%, false-positive rate of 4.9%, likelihood ratio of 9.3, and positive predictive value in the high-risk population in this study of 13.3%. Lowering the threshold to 1 point increased the sensitivity to 60.4% but increased the false-positive rate to 15.8%. Adding points for age increased the sensitivity to 67.9% but increased the false-positive rate to 24.3%. Results of using AAURA to detect trisomy 21 were nearly identical, with a sensitivity of 43.4% and false-positive rate of 4.9% at a 1 in 36 risk threshold and a sensitivity of 69.8% and false-positive rate of 26.1% at a 1 in 200 threshold. Trisomies 18 and 13 were detected with sensitivities of 80.0% and 100.0%, respectively, with either system. CONCLUSION: The modified ISS and AAURA are equivalent in screening for Down syndrome, with detection of approximately half of all trisomy 21 fetuses at a 5% false-positive rate.

Phase-contrast MR angiography of the portal venous system: preoperative findings in liver transplant recipients.

Sequential two-dimensional phase-contrast MR angiography can be used to accurately evaluate the anatomy, patency, and flow direction of the portal venous system and the presence, extent, and distribution of portosystemic collaterals. Its large field of view, insensitivity to the patient's body habitus, and graphic display format make this MR technique extremely useful for preoperative evaluation of patients with chronic liver disease and portal hypertension. This pictorial essay illustrates the spectrum of abnormalities seen on phase-contrast MR angiography of the portal venous system in patients with endstage liver diseases and portal hypertension.

Three-dimensional CT angiography of spontaneous portosystemic shunts.

Spontaneous portosystemic shunts (varices) are a well-known complication of severe liver disease and portal hypertension. Computed tomographic (CT) angiography was used to image the hepatic vasculature of 198 patients with end-stage liver disease in anticipation of liver transplantation. Performance of a delayed acquisition during the portal phase of enhancement enables evaluation of portal and variceal anatomy without the need for an additional injection of contrast material. Three-dimensional (3D) reconstruction of portal-phase CT angiograms enhances the perception of the courses and anatomic relationships of varices. This information is valuable for surgical planning. Common varices include the left gastric vein, short gastric veins, paraumbilical veins, and splenic vein; in cases of more unusual, complex shunts, 3D rendering is indispensable. By precisely demonstrating the courses of varices, CT angiography allows the surgeon to plan the operative approach and determine the need for surgical varix ligation or preoperative interventional embolization.

Adverse reactions to intravenous contrast media in patients treated with interleukin-2.

Seventy patients consecutively admitted to a single institution were treated with high-dose interleukin-2 (IL-2) and analyzed for determining the incidence and risk factors associated with reactions to i.v. contrast media. Patients with metastatic renal cancer (n = 44) or melanoma (n = 26) received 74 cycles of IL-2 administered at 2 to 6 x 10(6) U/m2/d for 10-21 days either alone or with lymphokine-activated killer (LAK) cells or tumor-infiltrating lymphocytes (TILs). Seventy-four computed tomography (CT) scans were performed before administration of IL-2; and 74, 59, and 35 CT scans were performed, respectively, 2, 6, and 10 weeks after administration of IL-2. Of the 168 scans performed after therapy with IL-2, non-ionic media were used in 110 and ionic media were used in 58. There were no reactions before administration of IL-2, but there were nine reactions after therapy with IL-2. Reactions to contrast media occurred 1-4 hours after media infusion and included fever, chills, emesis, diarrhea, rash, wheezing, hypotension, edema, and oliguria. Hospitalization was required in seven cases, including intensive care unit support in four, but all patients recovered fully. Contrast reactions were more frequent 2 weeks after therapy with IL-2 (eight of 74 scans, 11%) compared with 6 weeks after IL-2 (one of 59 scans, 1.7%), but the difference was not statistically significant (McNemar's test). Six patients who reacted to contrast 2 weeks after IL-2 treatment received contrast 4 weeks later: five had no reaction and only one experienced a reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebellar and frontal lobe hypoplasia in fetuses with trisomy 21: usefulness as combined US markers.

PURPOSE: To confirm that cerebellar hypoplasia is ultrasonographically recognizable in second-trimester fetuses with Down syndrome and determine whether the combination of frontal lobe shortening and cerebellar hypoplasia is superior to either measurement alone as a marker of this abnormality. MATERIALS AND METHODS: The frontothalamic distance (FTD) and transcerebellar diameter (TCD) were measured in 52 middle-trimester fetuses with euploid karyotypes and in 52 fetuses with Down syndrome. Receiver operating characteristic (ROC) curves were constructed with various thresholds for observed-to-expected ratios (O/Es) of the FTD, TCD, and average of these two parameters. RESULTS: The area under the average ROC curve, 0.80, was greater than that for either the FTD alone (0.75) or the TCD alone (0.76). At a 6% false-positive rate, the sensitivity for the detection of Down syndrome obtained with the average parameter was 34% better than that obtained with only the FTD and 12% better than that obtained with only the TCD. With an O/E threshold of 0.92 for the average parameter, an odds ratio of 16.3 and positive predictive value of 12.7% in the high-risk population were achieved. CONCLUSION: Although both measurements are individually statistically significant, the combination of TCD and FTD measurements may be superior to the use of either parameter alone as a marker of trisomy 21.

Assessment of fetal and placental blood flow in primates using contrast enhanced ultrasonography.

Ultrasonographic contrast agents that stay within the vascular space and do not cross the placenta may permit differentiation between the maternal and fetal portions of the placenta and may be clinically useful for diagnosis of placental abnormalities. This study was performed to assess the effects of Levovist (Schering AG, Berlin) on the placental circulation and to determine whether hemodynamic effects on the fetus occur. Ten studies were performed in five pregnant macaques (median weight, 9.15 kg; range, 6.15 to 11 kg; median gestational age, 121 days; range, 34 days to term) under anesthesia. Gray scale, color, and duplex Doppler sonographic scans of the fetus and placenta were acquired using a 5 MHz curved array transducer. Fetal heart rate, resistive index, and systolic-diastolic ratios were measured in the fetal middle cerebral artery, aorta, umbilical artery, and uterine artery before and after administration of contrast agent. The following dose regimen was tested: 5 ml of physiologic saline solution followed by 0.1 ml/kg of 300 mg/ml Levovist (diagnostic dose), 0.5 ml/kg of 400 mg/ml Levovist (maximum dose), and 5 ml physiologic saline solution. The order of diagnostic dose and maximal dose was randomized among animals. Color enhancement of the basal portions of the placenta was documented after administration of contrast agent. Heart rate and middle cerebral artery systolic-diastolic ratio did not change between baseline and injections. A 7% decrease of the resistive index from baseline to maximum dose was measured in the uterine artery (not significant). A 7.7% decrease in the systolic-diastolic ratio from baseline to maximum dose was recorded in the umbilical artery. However, an identical change was measured after saline solution was injected. The resistive index in the aorta increased by 2.6% from baseline to maximum dose, a change that was not significant (P > 0.5). Ultrasonographic contrast enhancement of the maternal circulation in placenta is demonstrated to be without significant effects on the fetal circulation as measured in this limited population.

Hepatic helical CT: effect of reduction of iodine dose of intravenous contrast material on hepatic contrast enhancement.

PURPOSE: To evaluate the effect of a reduction in iodine dose by altering volume and/or concentration of contrast material on hepatic contrast enhancement (HCE) values during hepatic helical computed tomography (CT). MATERIALS AND METHODS: One hundred eleven patients were randomized into four contrast material protocols according to concentration (in milligrams of iodine per milliliter)/volume (in milliliters)/grams of iodine: group 1, ioversol, 320/150/48; group 2, ioversol, 320/100/32; group 3, iohexol, 300/150/45; group 4, ioversol, 300/100/30. Helical CT protocols were identical for the four groups. Time-attenuation curves were constructed; the mean HCE, contrast enhancement index (CEI), and optimal liver scanning interval (OLSI) were calculated; and the results were compared statistically. RESULTS;: Time-attenuation curves, mean HCE, CEI, and OLSI of groups 1 and 3 were significantly superior to those for groups 2 and 4. Decrease in volume from 150 to 100 mliters decreased mean HCE by 27%, CEI by 69%, and OLSI from 80%-100% to 0%-43% at threshold levels of 40-60 HU. CONCLUSION: Decrease in iodine dose from 45-48 g to 30-32 g significantly decreases all HCE values, which potentially decreases detection of focal hypovascular hepatic lesions.