Sonographic evaluation of fetal growth: growth rate variability as a function of the interval between examinations

OBJECTIVE

Fetal growth rates determined on the basis of findings at two separate sonographic examinations can be used to detect growth abnormalities. This article determines the relationship between the length of the interval between examinations and the associated variability in measured fetal growth rates.

MATERIALS AND METHODS

We analyzed 1479 fetal measurements of the biparietal diameter, average abdominal diameter, and femur length from 539 normal pregnancies. Mean growth rates were computed as functions of gestational age. The standard deviation of the growth rate was computed as a function of the interval between examinations.

RESULTS

The standard deviation of fetal growth rates is relatively constant when the interval between examinations is 8-10 weeks or more, but increases substantially when the interval is fewer than 6 weeks.

CONCLUSION

From a purely statistical point of view, the optimal interval for assessment of fetal growth rates is 8-10 weeks or more. Shorter intervals, however, usually are mandated by the clinical situation. Correction factors can be used to determine the standard deviations and associated confidence intervals for fetal growth measured over a period of fewer than 10 weeks.

CT done 4-6 hr after CT arterial portography: value in detecting hepatic tumors and differentiating from other hepatic perfusion defects

OBJECTIVE

Nontumorous perfusion defects occur during CT arterial portography (CTAP) as normal variants or in cirrhosis, focal fatty infiltration, and portal vein obstruction. The purpose of this study was to determine whether delayed CT 4-6 hr after CTAP improves sensitivity to hepatic tumors and differentiates them from other hepatic perfusion defects.

SUBJECTS AND METHODS

CTAP was done at 1-cm increments on 26 patients for evaluation of hepatic tumors. Delayed CT scans were obtained 4-6 hr later in all patients. Two observers retrospectively reviewed the CT scans obtained during CTAP and recorded size, shape, and location of suspected hepatic tumors. Confidence levels were assigned for each tumor. The delayed CT scan was then interpreted in conjunction with the CT scans obtained during CTAP, and confidence levels were reassigned. Surgical correlation was obtained for all patients. In the 26 patients, 86 masses were found at surgery. The sensitivity and number of false-positives for both CTAP alone and CTAP combined with delayed CT were compared with a two-tailed Student t-test. Receiver-operating-characteristic analysis also was performed.

RESULTS

CTAP detected 73 (85%) of the 86 hepatic masses. Delayed CT had no effect on the sensitivity of CTAP. However, adding delayed CT decreased the total number of false-positives by 11, a statistically significant difference (p < .05). Receiver-operating-characteristic analysis revealed a significantly greater (p < .05) area under the curve (Az index) of 0.927 +/- 0.025 for CTAP combined with delayed CT compared with 0.886 +/- 0.032 for CTAP alone. Delayed CT was most useful for larger (> 1 cm) wedge-shaped perfusion defects and least useful for smaller (< 1 cm) round defects.

CONCLUSION

Delayed CT has no effect in detecting tumors but may be useful for differentiating tumors from other hepatic perfusion defects seen on CTAP. The greatest benefit of delayed CT is in evaluating regions obscured by large wedge-shaped perfusion defects on CT scans obtained during CTAP.

Arterial abnormalities following orthotopic liver transplantation: arteriographic findings and correlation with Doppler sonographic findings

OBJECTIVE

We studied the findings on conventional arteriography in patients who had suspected graft ischemia after orthotopic liver transplantation to determine the value of a single Doppler signal in predicting these lesions.

MATERIALS AND METHODS

We retrospectively reviewed selective visceral arteriograms with abnormal findings from 20 adults who had suspected graft ischemia after orthotopic liver transplantation and a single Doppler signal from the hepatic artery at the porta hepatis on sonograms obtained before arteriography. Arteriographic abnormalities were categorized according to morphology and location as follows: stenosis of recipient's hepatic artery, occlusion or stenosis of the transplanted extrahepatic artery, and occlusion or stenosis of the transplanted intrahepatic artery.

RESULTS

Twenty-three arteriographic abnormalities were detected: four recipient celiac axis stenoses, seven extrahepatic occlusions, nine extrahepatic stenoses, and two occlusions and one stenosis of the transplanted intrahepatic artery. Six of the extrahepatic occlusions, two of the extrahepatic stenoses, and none of the recipient artery stenoses or the intrahepatic occlusions or stenoses were correctly diagnosed on the basis of Doppler findings. One patient with both an extrahepatic stenosis and an extrahepatic occlusion was thought to have an intrahepatic occlusion, and two patients with mild (< 50%) extrahepatic stenoses and one with an intrahepatic occlusion were thought to have an extrahepatic occlusion.

CONCLUSION

A wide spectrum of abnormalities in the recipient's celiac axis or the transplanted arteries that may be associated with graft ischemia after orthotopic liver transplantation are often not detected or findings are misinterpreted on routine Doppler examination. In patients with suspected graft ischemia, visceral arteriography should be performed promptly to confirm the diagnosis and to allow early intervention.

Right common carotid artery reconstruction after extracorporeal membrane oxygenation: vascular imaging, cerebral circulation, electroencephalographic, and neurodevelopmental correlates to recovery

OBJECTIVE

Right common carotid artery (RCCA) ligation after extracorporeal membrane oxygenation by venoarterial bypass may contribute to lateralized cerebral injury. Reconstruction of this artery after extracorporeal membrane oxygenation has proved feasible but has not been evaluated for neurologic outcome in any substantial series of infants.

METHODS

We evaluated RCCA reconstruction in 47 infants treated with ECMO and compared their cerebrovascular and neuroanatomic imaging findings, electroencephalograms, and developmental outcomes with those of 93 infants who had no reconstruction. SUMMARY RESULTS: Color Doppler blood flow imaging revealed that carotid artery patency was usually obtained after RCCA reconstruction. Right internal carotid and bilateral anterior and middle cerebral arterial blood flow velocities were generally higher, and were more symmetrically distributed in infants with reconstructed RCCA. Electroencephalography did not disclose an increased risk of deterioration or marked abnormalities in infants after reconstruction, nor were neuroimaging findings consistent with an increased number of either focal or generalized abnormalities. Neurodevelopmental follow-up revealed no differences in the incidence of delays between those with a reconstructed RCCA and those with a ligated RCCA during the first year of life.

CONCLUSIONS

Reconstruction of the RCCA after extracorporeal membrane oxygenation may facilitate normal distribution of cerebral blood flow through the circle of Willis, and may augment both left and right middle cerebral artery blood flow immediately after decannulation. The long-term consequences of either ligation or reconstruction of the RCCA will require careful scrutiny, however, before either course is recommended routinely.

Role of selective arteriography in the diagnosis of a ruptured middle colic artery aneurysm

A case of a ruptured middle colic artery is reported. The diagnosis was initially overlooked and eventually made by selective arteriography. Aneurysms of visceral arteries are rare and rupture of them even more infrequent. Awareness of this potentially fatal and treatable entity should enable early detection by selective visceral arteriography. The roles of embolization and surgery in the management of visceral aneurysms are discussed.

Gastric and esophageal varices: 20-MHz transnasal endoluminal US

To image esophageal and gastric varices qualitatively and to measure esophageal varices quantitatively, 29 patients with portal hypertension underwent transnasal esophageal and gastric ultrasonography (US). Twenty-three patients underwent standard endoscopy. Endoluminal US demonstrated the varices as anechoic areas with communications in the submucosal, periesophageal, and perigastric regions, as well as ascites visualized through the gastric wall. Interobserver variation between two investigators for measurements of the largest esophageal varix in each patient was r value of .99 for diameter, r value of .99 for cross-sectional surface area, and r value of .98 for circumference. Endoscopy for evaluation of gastric varices had a sensitivity of 48% and a specificity of 50% and for evaluation of esophageal varices had a sensitivity of 94% and a specificity of 17%. Periesophageal and perigastric varices could not be visualized at endoscopy. Transnasal esophageal US, a new imaging technique with which to detect and measure esophageal varices, is a more sensitive modality than endoscopy for the detection of gastric varices.

Treatment of iatrogenic femoral artery injuries with ultrasound-guided compression

Iatrogenic injuries of the groin are becoming more common after increasingly sophisticated vascular intervention. These injuries are accurately detected by duplex and color Doppler ultrasonography. Recent treatment of these lesions by ultrasound-guided compression repair (UGCR) has been described. During a 1-year period we identified 18 femoral artery injuries, including 17 pseudoaneurysms and one arteriovenous fistula. Three of the pseudoaneurysms thrombosed spontaneously before attempted treatment. The remaining 15 lesions underwent a trial of UGCR. Successful closure was accomplished in 10 patients (56%). Seven of these lesions were successfully treated during the initial session, and thrombosis was accomplished after repeat compression in three additional lesions. Three patients who were given anticoagulants had a failed UGCR, but their pseudoaneurysms thrombosed after administration of anticoagulants was discontinued. Two patients had failed UGCR and required operation. Seven (88%) of eight patients who were not given anticoagulants were successfully treated. In contrast only two (29%) of seven patients given therapeutic doses of anticoagulant medication were successfully treated by the technique. There was no statistical difference between mean pseudoaneurysm diameter, mean width and length of pseudoaneurysm neck, or depth of pseudoaneurysm neck from skin surface in patients in whom successful initial closure was achieved when compared with those patients in whom the initial attempt failed. UGCR is a safe, simple, noninvasive technique that can be used to treat many femoral artery injuries that traditionally were treated with surgery. The technique can be applied by any laboratory that has the necessary ultrasonography equipment and is currently the method of choice for treating uncomplicated iatrogenic femoral artery injuries at our institution.

Transnasal US of the esophagus: preliminary morphologic and function studies

High-frequency catheter-based ultrasound (US) transducers can be inserted into the esophagus transnasally to evaluate esophageal wall structures. Studies were performed in two sheep esophagus specimens in vitro, in 17 healthy human subjects, and in 16 patients with esophageal abnormalities (eight with achalasia, four with scleroderma, three with esophageal carcinoma, and one with esophagitis). In the sheep specimens, endoluminal US delineated seven layers of the esophageal wall; these results correlated closely with histologic findings. Real-time US of the normal esophageal wall was performed during resting and swallowing. Muscles at the lower esophageal sphincter (LES) were shown to be thicker than muscles in the body of the esophagus. Thickening of the muscular layers at the LES in achalasia, dilated blood vessels within the submucosa in esophagitis, and fibrotic changes within the muscular layers in scleroderma were demonstrated. Extramural structures adjacent to the esophagus were also seen. These preliminary results suggest that transnasal esophageal US may become an important diagnostic tool in evaluation of the esophagus.

Can detection of the yolk sac in the first trimester be used to predict the outcome of pregnancy? A prospective sonographic study

Recent reports have indicated that identification of the yolk sac should precede the detection of the embryo in a normal first-trimester sonographic examination and that failure to visualize a yolk sac strongly suggests an abnormal intrauterine pregnancy. A first-trimester prospective study was performed in 163 normal and 49 abnormal consecutive singleton gestations. All women were examined both abdominally and transvaginally, with pregnancy outcome determined by delivery of a normal infant or a spontaneous abortion. The yolk sac was analyzed in all patients in whom an embryo was not identified (n = 76). When the yolk sac was identified, the following was found: by the abdominal approach with the mean sac diameter (MSD) less than 27 mm (n = 15), nine gestations were normal and six were abnormal, and by the transvaginal approach with the MSD less than 18 mm (n = 13), seven gestations were normal and six were abnormal. The presence of a yolk sac was not consistently predictive of a normal early pregnancy. When the yolk sac was also not identified, the following was found: abdominally with the MSD less than 27 mm (n = 41), 19 gestations were normal and 22 were abnormal, and transvaginally with the MSD less than 18 mm (n = 11), six gestations were normal and five were abnormal. Absence of the yolk sac was not consistently predictive of a spontaneous abortion. When using the MSD range (20-27 mm abdominally and 7-16 mm transvaginally), over which the yolk sac but not the embryo should be identified sonographically, the yolk sac was again not consistently visualized. On abdominal sonograms, the yolk sac was present and absent in three and 10 patients, respectively, for both normal and abnormal pregnancies. On transvaginal sonograms, the yolk sac was present and absent in seven and five normal gestations and in six and four abnormal gestations, respectively. The results of this study suggest that detection of the yolk sac in the first trimester is not an early predictor of pregnancy outcome.

CT-pathologic correlation of axillary lymph nodes in breast carcinoma

A prospective study was performed to determine whether thoracic CT yielded useful information regarding the status of axillary lymph nodes (LNs) in patients with breast cancer. Thirty-five consecutive patients with clinically suspected stage II or III breast carcinomas were scanned preoperatively from the supraclavicular regions to the lung bases. Axillary LNs measuring greater than or equal to 1 cm were considered abnormal. The lymph nodes were classified according to their relationship to the pectoralis muscle. Extracapsular lymph node extension was diagnosed when there was irregularity and spiculation of the lymph node margin with surrounding fatty infiltration. Correlation with axillary dissection was obtained in 20 patients, giving a positive predictive value for axillary metastases of 89% with 50% sensitivity, 75% specificity, and 20% negative predictive value. CT was also able to detect the level of axillary involvement accurately when the lymph nodes were enlarged and to evaluate extracapsular LN extension. Although superior to physical examination, CT was not an accurate predictor of axillary LN involvement, primarily because of its low negative predictive value.

Usefulness of a short femur in the in utero detection of skeletal dysplasias

In 28 fetuses studied during a 4 1/2-year period, the initial femur was below 2 standard deviations (SDs) of the mean when compared with the biparietal diameter. These fetuses were considered at risk for skeletal dysplasias and were followed up. Studies were performed at a mean gestational age of 26.7 weeks (range, 15.3-41.0 weeks). Group 1 had a femur length 1-4 mm below the 2-SDs line (range, -2.0 to -4.0 SDs); no other abnormalities were detected. Interval examination of 12 femurs showed that 10 either remained shortened to the same degree or had a growth spurt. At birth, all subjects were healthy except one with mild growth retardation and one with a chromosomal abnormality. Of the two subjects that failed to continue normal growth, one was healthy and the other was a heterozygous achondroplastic dwarf. Group 2 had greater femoral shortness; all measurements were more than 5 mm below the 2-SD line (range, -4.3 to -31.0 SDs). All had fetal abnormalities and significant skeletal dysplasias. The authors conclude that the number of millimeters below the 2-SDs line is an accurate, easy criterion for evaluation of femoral length.

Anterior protrusion of retroperitoneal processes. A mimic of lesser sac or gastrohepatic masses

The space between the left lobe of the liver and the lesser curvature of the stomach normally contains intraperitoneal structures. These include the gastrohepatic recess of the greater peritoneal cavity, the medial recess of the lesser sac and the interposed gastrohepatic ligament. An anterior protrusion of retroperitoneum can project into this space, dorsal to the posterior reflection of the medial compartment of the lesser sac. Tumors that extend into this fossa are anterior and medial to the fundic and upper body region of the stomach. These tumors may cause confusion regarding their origin if the radiologist is not aware of the existence of this retroperitoneal protrusion. Between 1982, and 1986, 183 patients with pancreatic cancer were hospitalized at our institution, 63 of whom had computed tomography (CT) scans of the abdomen. Four of these patients (6.3%) demonstrated direct tumor extension anterior to the stomach. During this same period, four large benign retroperitoneal tumors also exhibited this finding. Masses in the gastrohepatic interval between the liver and stomach can be extensions of retroperitoneal processes and should not be assumed to represent intraperitoneal involvement.

Color Doppler imaging of the iliofemoral region

Color Doppler imaging has been used to evaluate a variety of abnormalities in the iliofemoral region. This pictorial essay demonstrates how use of color Doppler techniques aids in the diagnoses of iliofemoral pseudoaneurysms, fluid collections, aneurysms, arteriovenous fistulas and malformations, venous thrombosis, vascular grafts, and soft-tissue masses including tumors and benign lymphadenopathy.

Circle of Willis in newborns: color Doppler imaging of 53 healthy full-term infants

To establish the usual pattern of flow in the circle of Willis in newborns, the authors scanned 53 healthy full-term infants within 3 days of birth with color Doppler imaging. All examinations were performed and images interpreted by the same experienced individuals. The basilar, internal carotid (ICA), and anterior and middle cerebral arteries were seen in all infants. Vertebral, posterior cerebral, superior cerebellar, and posterior communicating (PCoA) arteries were seen in most infants. PCoA flow was from the ICA toward the posterior cerebral artery in 73 (98.6%) of the 74 vessels that were seen. Flow in the anterior communicating artery was seen in six infants, indicating dependence of an anterior cerebral artery on contralateral ICA perfusion. Two pitfalls involving the distal portion of the ICA were noted: This vessel could be confused with the proximal portion of the anterior cerebral artery or cavernous sinus if real-time images were not interpreted carefully. Variant patterns of flow included tortuous basilar arteries (n = 2), reversed PCoA flow (n = 1), and inferior angulation of the proximal portions of the anterior cerebral arteries (n = 2). Color Doppler imaging allows a detailed analysis of the circle of Willis in newborns and detection of some anatomic variations.

Absence of end-diastolic umbilical artery blood flow predicts poor fetal outcome despite normal blood gases

A case is reported in which the fetal acid-base status was assessed by means of cordocentesis in a fetus without end-diastolic umbilical artery blood flow. The absence of end-diastolic flow was not associated with acidosis or hypoxia. However, the fetal condition deteriorated 3 days later, which suggests that even with a normal fetal acid-base status, an extended margin of safety cannot be assumed with the absence of end-diastolic umbilical flow.