Recent topics related to perinatal fetal ultrasound such as fetal intracranial anatomy, fetal circulation, congenital central nervous system anomaly, intrauterine sonographic assessment of the embryo, and three-dimensional ultrasonography are discussed in this review article.
Conventional color Doppler flow imaging (CDFI) permits blood flow direction and relative velocity to be detected and shown as a color-encoded display. However, its capability to depict flow has proven to be limited and unsatisfactory in Intraoperative use. Recently developed power Doppler imaging (PDI) permits integrated power of flow to be depicted in enhanced display, but neither flow direction nor flow velocity is detected. In order to evaluate the diagnostic potential, of this technique, we used an upgraded color Doppler flow ultrasound system, the Toshiba SSA-260A-CE, which is capable of both CDFI and PDT, in 8 neurosurgical operations on seven patients. Their conditions included one giant AVM, two meningiomas, two metastatic tumors, one glioma and one arachnoid cyst. Color Doppler imaging was attained by placing either the 5 MHz sector or 7.5 MHz linear transducer on the dura mater or the cerebral surface in the area exposed by craniotomy. Both CDFI and PDI were found to be useful diagnostic tools. PDI was more sensitive for depicting lesions with slow flow, and was useful for delineating the margin of the slow-flow AVM. CDFI provided information on flow direction and speed, despite poor representation of vascular structure. Thus, combined utilization of both techniques, complementing the advantages of each for neurosurgical operations, is recommended.
Objective: It is difficult to define the boundary of a tumor grossly during glioma surgery. Because of this, it is often necessary to use some landmarks. In order to verify the localization of the tumor and the range of tumor removed in the process of surgery, we measure the extent of tumor removal using a stereotactic device and a marker is used as a navigator to define the deep boundary in the process of tumor removal. We will present this method and the device that we have developed, and discuss its usefulness. Method: The subjects were 21 patients with glioma. The stereotactic device was used to set landmarks on the boundary of the tumor or the boundary of removal on CT or MRI. A marker was inserted by perforation and retained, and craniotomy was performed. The glioma was removed under microscopic observation while the marker was visualized by echo during surgery. The marker that we developed was made of silicon containing two stainless steel balls. The material could be visualized by echo, X-ray and CT. Conclusion: After the start of surgery, we often experience difficulty in defining the deep boundary because of CSF leakage. Retaining a marker enables us to define the boundary of the tumor without missing landmarks. This makes it possible to perform surgery accurately and in a short time. This method can be carried out using existing stereotactic devices, and does not require any special technique. The device that we have developed can be easily visualized by echo and X-ray. Therefore, this method appears to be useful for glioma surgery.
We undertook TCD examination combined with transesophageal echocardiography (TEE) and measurements of hematological markers for coagulation, fibrinolysis and platelet function to clarify the clinical significance of micro-embolic signals derived from the heart. We examined nine patients with prosthetic valves including two with cardioembolic stroke (CE) and 11 CE patients without prosthetic valves. All the patients were receiving anticoagulation therapy at the time of the study. TCD study demonstrated 3-54/30 min micro-embolic signals in six of the nine patients with prosthetic valves, but no signal in those without valve replacement. TEE study demonstrated cavitation phenomenon in eight of the nine patients with prosthetic valves, but in none of the patients without valve replacement. No other findings of TEE or hematological examination were correlated with the frequncy of micro-embolic signals. These results indicate a close relationship between cavitation phenomenon and micro-embolic signals in patients with prosthetic valve. Ordinary anticoagulation (INR: international normalized ratio 2.0-3.0) does not reduce the frequency of micro-embolic signals in patients with prosthetic heart valve. However, very high intensity anticoagulation (INR>3.5) might decrease the frequency of micro-embolic signals. Further studies are necessary to clarify the clinical significance of microembolic signals.
Transcranial Doppler sonography (TCD) for investigation of the vertebro-basilar (VB) system was performed in one patient with left subclavian artery (LSCA) occlusion and the other with LSCA stenosis before and after axial artery to axial artery bypass. Preoperative Doppler waveforms of the left vertebral artery (VA) of the patient with LSCA stenosis showed transient reversal, whereas the patient with LSCA occlusion showed complete reversal. Increased blood flow in the right VA, suggested by an increased flow velocity, apparently compensated for flow in the left VA. TCD done shortly after the operation revealed that the direction of flow in the left VA was still transiently reversed in both cases. Flow reversal continued to be mild and limited to the end-diastolic or presystolic periods in the patient with LSCA stenosis, whereas the patient with LSCA occlusion showed gradually progressive reversal with the last waveforms being completely reversed.
Transcranial Doppler sonography is frequently used to monitor cerebral blood flow velocities during open heart surgery. There was little information about Doppler findings in patients with congenital heart diseases and valvular heart diseases. This study included 12 women and six men, with a mean age of 40.6 years. Two patients had ventricular septal defect, four were diagnosed as having atrial septal defect, and one had both defects. Eleven patients underwent surgical replacement of heart valves. Two underwent aortic valve replacements and two underwent surgery on both the aortic and mitral valves. In seven patients, the mitral valve was replaced because of mitral regurgitation. The maximum, mean, and minimum flow velocities of the left middle cerebral artery (MCA) were measured intraoperatively before and after replacement. In the patients with aortic insufficiency and ventricular septal defect, the mean and diastolic flow velocities were markedly reduced on Doppler recordings before valvular replacement. In the patients with aortic insufficiency, a bisferious pulse was found on the Doppler spectra. In contrast, in the patients with mitral regurgitation and atrial septal defect, the Doppler waveforms showed normal findings preoperatively. In the patients with raised intracranial pressure, a high value of PI and low diastolic flow velocities were found on the TCD spectra. The same findings were sometimes seen in the patients with aortic insufficiency or ventricular septal defect. In patients with mitral insufficiency or atrial septal defect, the Doppler spectra showed no change on the TCD records postoperatively. Spiky contours were detected by Doppler in the patients with valvular heart disease secondary to subacute endocarditis. It is concluded that TCD could provide an approximation of changes in cerebral blood flow velocity in patients with valvular heart disease and ventricular septal defect.
Transcranial Doppler (TCD) findings in a neonatal girl with a scalp arteriovenous malformation (AVM) are reported. She was born with a large scalp AVM in the left temporal region, which caused uncontrollable cardiac failure. Preoperative color Doppler showed that the AVM was fed only by the external carotid artery, and that the flow velocity in the left middle cerebral artery (MCA) was lower than that in the right MCA. The left superficial temporal artery was ligated, followed by surgical resection of the AVM 37 days after birth. TCD findings demonstrated a transient rise in the left MCA flow velocity immediately after resection and its subsequent normalization. The pulsatility index of the straight sinus was preoperatively high and became normal after resection. These TCD findings suggested improvement of both the blood flow in the left MCA region and intracranial venous circulation after resection of the AVM. TCD proved to be a noninvasive and useful monitor of neonatal and infantile vascular disorders.