Color Doppler ultrasound velocimetry of internal carotid arteries in normal pregnancies

BACKGROUND: There are few reports on maternal cerebral circulation during pregnancy. Using the hypothesis that cerebral blood flow resistance decreases progressively with advancing gestational age (GA) as a consequence of estrogenic effects on the vascular system during pregnancy, we calculated the pulsatility index (PI) and the mean velocity (MV) of the maternal right internal carotid artery (ICA) in order to build fitted reference centiles. METHODS: A total of 315 pregnant women with a single fetus were studied at 20-42 weeks' gestation. The patients had uncomplicated singleton pregnancies and were without any known fetal or maternal risk factors. Duplex color ultrasound with a pulsed Doppler scanner (7.5 MHz) was used to determine the PI and MV of the maternal ICA. RESULTS: Among the 315 healthy pregnant women, the PI of maternal ICA decreased progressively with advancing GA, PI50th = Exp (0.3124-0.0084 x GA), (p = 0.0003), during the second half of pregnancy. The predicted 50th percentile PI values of the ICA decreased from 1.117 (5th% = 0.755, 95th% = 1.654) at 24 weeks' gestation to 0.917 (5th% = 0.659, 95th% = 1.448) at 40 weeks' gestation. The MV of the maternal ICA also decreased progressively with advancing GA, MV50th = Exp (3.855-0.0093 x GA), (p = 0.0005), during the second half of pregnancy. The predicted 50th percentile MV values in the ICA decreased from 37.811 cm/sec (5th% = 24.177 cm/sec, 95th% = 59.138 cm/sec) at 24 weeks' gestation to 32.591 cm/sec (5th% = 20.818 cm/sec, 95th% = 51.021 cm/sec) at 40 weeks' gestation. CONCLUSIONS: Both the PI and MV of the maternal ICA decreased with GA during the second half of normal pregnancy as a result of intracerebral vessel dilatation.     

Transcranial Doppler in the evaluation of internal carotid artery dissection

BACKGROUND AND PURPOSE: A subject with dissection of the internal carotid artery (ICA) may present with a variety of symptoms, from headache to stroke. Thus far, it has not been possible to identify the subset of patients at risk for cerebral ischemia. Because the majority of these ischemic events are secondary to embolic phenomena, we used transcranial Doppler (TCD) evaluation with emboli monitoring to study 17 consecutive patients with ICA dissection treated at Harborview Medical Center, Seattle, Wash, during a 2-year period from 1992 until 1994. METHODS: Ten patients with ICA dissection secondary to trauma and seven with spontaneous ICA dissection were diagnosed by carotid angiography and studied by TCD from the time of diagnosis through initiation of therapy. Emboli monitoring was performed in the middle cerebral artery (MCA) ipsilateral to the dissection at the initial evaluation and intermittently thereafter to ensure that the emboli stopped with treatment. RESULTS: Emboli were detected in the MCA distal to the dissection in 10 of 17 patients (59%). Patients with microemboli detected by TCD presented with a stroke (70%) much more frequently than those without emboli (14%) (P=.0498). The presence of a pseudoaneurysm did not increase the risk of either microemboli or stroke. CONCLUSIONS: We have demonstrated a high incidence of intracranial microemboli in the MCA distal to carotid dissections and a significant correlation between the presence of emboli and stroke. TCD can therefore be used as an adjunctive tool to manage patients with suspected carotid dissection and may prove useful in evaluating the efficacy of treatment in reducing microemboli and subsequent stroke.     

Doppler color echography in the diagnosis of impotence

This study reports the experience achieved with duplex and color Doppler ultrasonography in 120 impotent patients. The following morphodynamic parameters of the cavernosal arteries were studies before and after intracorporal injection of a mixture of vasoactive drugs: arterial diameter, wall pulsatility, morphology of the spectral waveform, peak systolic velocity, end diastolic velocity and flow volume. The veno-occlusive mechanism of the corpora cavernosa was studied directly by determination of flow along the deep dorsal vein of the penis and indirectly by serial evaluation of the diastolic flow of the cavernous arteries.     

Transcranial Doppler ultrasound battery reliably identifies severe internal carotid artery stenosis

BACKGROUND: The clinical significance of plasma concentration of matrix metalloproteinase 9 (MMP-9) was investigated in patients with gastric cancer. METHODS: Plasma was obtained from 138 healthy individuals and 70 patients who underwent gastrectomy for gastric cancer at Aichi Cancer Centre between August 1994 and July 1995. Plasma concentrations of MMP-9 were measured using a one-step sandwich enzyme immunoassay employing monoclonal antibodies. RESULTS: Patients with gastric cancer had plasma higher concentrations of MMP-9 than normal subjects. Postoperative concentrations of MMP-9 were lower than preoperative levels. In addition to patients with advanced cancer, those with early gastric cancer also exhibited higher mean values of and positivity rates for MMP-9 than healthy individuals. Preoperative plasma MMP-9 concentration correlated closely with Union Internacional Contra la Cancrum tumour node metastasis (pTNM) stage, severity of T, N and M classification, and tumour size. CONCLUSION: Plasma MMP-9 concentration can be used for detection of primary or recurrent gastric cancer, and for estimation of tumour extent.     

Color Doppler ultrasonography in retinitis pigmentosa. Preliminary study

PURPOSE: Retinitis pigmentosa is a bilateral retinal degeneration. The primary disorder is still debated. METHODS: We performed a prospective investigation of the ocular circulation directly by color Doppler imaging (CDI). A total of 28 eyes of 14 patients (8 men and 6 women, affected with retinitis pigmentosa) were recruited for this study. For each case were evaluated protosystolic velocity and the resistive index of the ophthalmic artery, central retinal artery, posterior ciliary arteries and choroid. These values, furthermore, have been compared with a control group. RESULTS: The results of the CDI in the group of RP and in the CG were: in the OA: PSV 31.177 +/- 5.119 cm/sec vs 36.700 +/- 3.152 cm/sec (p < 0.007); RI 0.713 +/- 0.058 vs 0.717 +/- 0.019 (p < 0.0839); in the CRA PSV 7.075 +/- 1.611 cm/sec vs 12.710 +/- 2.795 cm/sec (p < 0.001); RI 0.560 +/- 0.062 vs 0.550 +/- 0.051 (p < 0.234); in the PCA: PSV 8.569 +/- 3.408 cm/sec vs 14.100 +/- 2.571 cm/sec (p < 0.001) with RI 0.634 +/- 0.090 vs 0.681 +/- 0.045 (p < 0.145). In the CHO: PSV 12.312 +/- 2.327 cm/sec vs 16.170 +/- 1.846 cm/sec (p < 0.001) with RI 0.581 +/- 0.072 vs 0.638 +/- 0.050 (p < 0.065). CONCLUSION: Our results suggest that in the affected eyes there is a statistically significant reduction in blood flow in ophthalmic and ciliary arteries. These data offer new views on the retinitis cause of pigmentosa and possible therapeutics to be studied.     

The agreement between colour Doppler systems in measuring internal carotid artery peak systolic velocities

The study was undertaken to determine if the internal carotid artery peak systolic velocities (ICA PSVs) measured by two colour Doppler imaging systems (Acuson 128 and Siemens Quantum) agree sufficiently for the two systems to be interchangeable in evaluating carotid artery disease. One operator obtained blinded measurements of ICA PSV in 63 prospective nonrandomized patients at risk of stroke. The operator examined 20 patients in the first cohort to assess the intraobserver variation, and 43 patients in the second cohort to assess the limits of agreement between the systems. In vitro comparisons of the systems were also undertaken, using both string and flow phantoms. Excluding one outlier, the intraobserver reproducibility coefficient for both machines was 0.48 m s-1. The limits of agreement (within which 95% of differences lie) between systems were -0.47 to 0.45 m s-1. This reduced to -0.39 to 0.33 m s-1 when the one outlier was excluded. This is within the intraobserver reproducibility range. In vitro data show little intersystem variation with phantom velocity. Intratransducer differences increase when the Doppler angle is increased using the string phantom; maximum differences: Acuson 0.30 m s-1 (42%) and Siemens 0.32 m s-1 (32%). These are within the in vivo reproducibility range. Intratransducer difference decreases when the Doppler angle is increased using the flow phantom, maximum differences: Acuson 0.05 m s-1 and Siemens 0.07 m s-1. The results show the systems agree sufficiently to be interchangeable in evaluating carotid artery disease; however, errors in maximum PSVs, caused by operator or system variation, may lead to errors in percent stenosis grading of the carotid arteries.     

Determination of arterial diameters, length and mass of the plaque, and theoretical volume in the internal carotid artery by quantitative vascular echography

To study the evolution of atherosclerosis, the consensual changes that occur in the arterial wall, lumen, and atheroma must be evaluated. The authors propose a new, noninvasive method of obtaining arterial diameters, length and mass of plaque, and theoretical volume in the internal carotid artery. The study was performed in 37 patients with different degrees of atherosclerosis (from 20% to 50%). All patients underwent echo examination. Long-axis tomographic planes were recorded with the same angle of incidence by placing a goniometer around the neck. Furthermore, the arterial diameters and the plaque length were measured from photorecordings, and theoretical arterial volume (sum of two bitruncated semiellipsoids), residual volume (Simpson's integral rule), and plaque mass (difference between theoretical vascular volume and residual volume) were calculated. Intraobserver and interobserver variability and reproducibility were tested in all the measurements and calculations. Intraobserver/interobserver variability and reproducibility were found to be less than 8% according to all measurements and calculations. These results indicate that the method is reproducible and allows noninvasive, quantitative assessments of vascular geometry in evolving atherosclerosis.     

Fibromuscular dysplasia of the internal carotid artery: a clinicopathological study

A combination of Southern blot analysis on a panel of tumor-derived somatic cell hybrids and fluorescence in situ hybridization techniques was used to map YACs, cosmids and DNA markers from the Xp11.2 region relative to the X chromosome breakpoint of the renal cell carcinoma-associated t(X;1)(p11;q21). The position of the breakpoint could be determined as follows: Xcen-OATL2-DXS146-DXS255-SYP-t(X;1)-TFE 3-OATL1-Xpter. Fluorescence in situ hybridization experiments using TFE3-containing YACs and cosmids revealed split signals indicating that the corresponding DNA inserts span the breakpoint region. Subsequent Southern blot analysis showed that a 2.3-kb EcoRI fragment which is present in all TFE3 cosmids identified, hybridizes to aberrant restriction fragments in three independent t(X;1)-positive renal cell carcinoma DNAs. The breakpoints in these tumors are not the same, but map within a region of approximately 6.5 kb. Through preparative gel electrophoresis an (X;1) chimaeric 4.4-kb EcoRI fragment could be isolated which encompasses the breakpoint region present on der(X). Preliminary characterization of this fragment revealed the presence of a 150-bp region with a strong homology to the 5' end of the mouse TFE3 cDNA in the X-chromosome part, and a 48-bp segment in the chromosome 1-derived part identical to the 5' end of a known EST (accession number R93849). These observations suggest that a fusion gene is formed between the two corresponding genes in t(X;1)(p11;q21)-positive papillary renal cell carcinomas.     

Predicting hemodynamic ischemia by transcranial Doppler monitoring during therapeutic balloon occlusion of the internal carotid artery

PURPOSE: Our objective was to evaluate the sensitivity of transcranial Doppler (TCD) sonographic monitoring during permanent balloon occlusion of the internal carotid artery (ICA) in predicting hemodynamic ischemia. METHODS: Thirty-two consecutive patients underwent controlled therapeutic balloon occlusion of the ICA. Selection criteria included assessment of the circle of Willis by compression angiography, clinical tolerance during a 20-minute test occlusion, and TCD monitoring of the ipsilateral middle cerebral artery. The mean blood flow velocity (MBFV) (n = 32) and pulsatility index (PI) (n = 28) were recorded. In 25 patients, MBFV changes upon motor stimulation were recorded before and after ICA occlusion. RESULTS: Twenty-eight (88%) of the patients had no complications. Three patients suffered delayed symptoms 30 minutes to 20 hours after balloon detachment. Two of these patients recovered spontaneously within 1 day, the other improved after extracranial/intracranial (EC/IC) bypass surgery. One patient, who did not tolerate the test occlusion, suffered a hemodynamic stroke despite EC/IC bypass before permanent balloon occlusion. No embolic complications occurred. The mean MBFV reduction was 20% (range, 0% to 55%); the mean PI reduction was 20% (range, 0% to 56%). No complications occurred in patients who had mild MBFV and PI reduction (30% or less, n = 21). All three patients with severe MBFV or PI reduction (> 50%) had neurologic symptoms. Among those with moderate MBFV or PI reduction (30% to 50%, n = 8), symptoms developed in only one patient who had moderate reduction of both MBFV (33%) and PI (38%). Motor vasoreactivity showed wide variation and was markedly reduced in two symptomatic patients. CONCLUSION: TCD monitoring reflects changes in cerebral hemodynamics after therapeutic balloon occlusion of the ICA. MBFV and PI reductions under 30% are highly predictive of clinical tolerance. A reduction of more than 50% may be a critical threshold for the occurrence of symptoms; in such cases, EC/IC bypass should be considered before proceeding with permanent balloon occlusion.     

Preliminary study in differential contrast echography

Microbubble-based contrast agents have backscattering properties that differ greatly from those of soft tissues. These agents exhibit nonlinear scattering properties in response to incident acoustic energy, causing harmonic components in reflected energy. Even in linear scattering conditions, an important difference is observed in the frequency dependence of their backscatter coefficient, when compared to that of tissues. In this situation, any such differential behaviour can be exploited by imaging instrumentation to enhance the detection of agent-containing vessels against background tissue. The resulting B-mode image brightness (or pixel level) can thus be the representation of a local parameter computed from radio frequency (rf) signal processing of the raw echoes. The object of this article is to report on parametric imaging studies performed with Sonovue (formerly code named BR1, Bracco Research SA), aimed at assessing the contrast-enhancing potential of spectral rf signal processing. The technique used, termed here "differential contrast echography" (DCE), is applicable in real-time B-mode imaging. It is based on an on-line subtractive approach, using dual-channel signal processing to implement differential filtering and demodulation. In this preliminary work, DCE was implemented off-line, on rf echo signals digitised from commercial B-mode scanners. Data acquisition, DCE processing and complete B-mode image reconstruction were programmed on a personal computer. The images presented were produced from test phantoms as well as animal phased array scanning. The phantom included a flow channel, background scattering material, fixed echogenic targets and echo-free regions. Animal scanning was performed on rabbit liver. The results obtained from DCE show promising contrast-enhancing properties. The regions containing no contrast agent are significantly suppressed from the image, preferentially leaving the regions perfused by the contrast agent. This property was favourable to experimenting with image-overlay presentations, superimposing colour-coded DCE imaging with standard log-compressed grey-scale B-mode, in a way analogous to duplex imaging combining colour Doppler and B-mode.     

Noninavasive angiography for the diagnosis of carotid artery disease using Doppler ultrasound (carotid artery Doppler)

To detect stenosis in the carotid artery with a bidirectional continuous-wave Doppler ultrasound device, the following noninvasive procedure, applied on 800 patients and compared with 249 angiograms of 186 patients, has proved to be about 90% reliable. Measurements of flow signals were taken over the terminal branches of the ophthalmic artery (supratrochlear and supraorbital arteries) and averaged. Compression of superficial temporal and facial arteries revealed flow direction and common carotid artery compression revealed the supplying blood vessel and the effectiveness of the circle of Willis. Measurements over the common carotid arteries were used to evaluate peripheral resistance. A set of eight criteria was used; the diagnostic value of each criterion was calculated by comparing 138 pathological Doppler findings in 123 patients with the angiograms. If reverse flow direction in supratrochlear or supraorbital artery was used alone, only 43% correct diagnoses would have resulted. A more severe stenosis is not necessarily correlated with a more weighted criterion; a subset of criteria is less efficient than the combination of all criteria. Application during 32 extracranial endarterectomies on 28 patients informed the surgeon immediately about the hemodynamic effect of the surgical intervention. Rethrombosis was diagnosed in two patients by postoperative Doppler examination.     

Duplication of the extracranial internal carotid artery

We describe a case of duplication of the left internal carotid artery from a point 1 cm distal to the origin to the proximal petrous segment where the vessel reunites. Duplication and fenestration of the internal carotid artery are discussed. A review of embryologic development is presented. Identification of these entities is important, especially in patients who require surgical intervention involving the internal carotid artery.     

Congenital absence of the internal carotid artery

The aim of this study was to adapt the single-breath technique with positive expiratory pressure to measure exhaled nitric oxide (eNO) in infants. We hypothesized that exhaled eNO was greater in wheezy than in healthy infants. We studied 30 infants (16 wheezy and 14 healthy). The forced expiratory volume in 0.5 s (FEV0.5) was determined with the raised volume rapid thoracic compression technique, and eNO was measured during constant expiratory flow with a rapid-response chemiluminescence analyzer. After passive inflation to a preset pressure of 20 cm H2O, thoracic compression with an inflatable jacket caused forced expiration to occur through a face-mask with an expiratory flow resistor attached. During the forced expiration, the jacket pressure was increased to maintain a constant driving mouth pressure and hence a constant expiratory flow (50 ml/s). The mean level of eNO in the wheezy infants (31.8 ppb) was significantly higher than the level in healthy infants (18.8 ppb) (p = 0.03). A family history of atopy in parents was associated with increased eNO levels (p < 0.001) independent of age, sex, weight, length, wheezing, and FEV0.5. We conclude that the single-breath technique with positive expiratory pressure is a feasible method for measuring eNO in infants. Levels of eNO were significantly higher in wheezy infants and in those with a family history of atopy.     

Pseudo-tandem stenosis of the internal carotid artery

Two cases of pseudo-tandem stenosis of the internal carotid artery are presented. Proximal stenosis was produced by a large, focal atherosclerotic plaque. The severe intracranial "stenosis" was thought to be an angiographic artifact. Repeat cerebral angiography after carotid endarterectomy revealed normal intracranial arteries. The recognition of this entity is important because a decision to operate is based largely upon angiographic findings.     

Angioplasty of the occluded internal carotid artery

PURPOSE: To review patients who have presented with acute strokes from a middle cerebral artery occlusion in whom in addition to the middle cerebral artery thromboembolus, an internal carotid artery occlusion has been present, and in whom angioplasty of these totally occluded internal carotid arteries has bee n successful. METHODS: We reviewed retrospectively our experience in treating a cute stroke patients with intracranial, intraarterial urokinase. Six of 27 patients had internal carotid artery occlusions in addition to middle cerebral artery occlusions. Two patients presented with spontaneous carotid dissections for wh ich no further intervention from the ipsilateral internal carotid artery was attempted. In the remaining four internal carotid artery occlusions secondary to atherosclerotic disease, standard guide wires and catheters were negotiated across the level of the internal carotid artery occlusion, which expedited intracranial catheterization for thrombolysis. Subsequently, angioplasty of the internal carotid artery was performed. RESULTS: All four occluded internal carotid arteries could be traversed. No new neurologic deficits occurred. No vascular injuries occurred. No deaths occurred. Four- to 6-month follow-up showed all four internal carotid arteries remained patent. CONCLUSION: In acute occlusions of the internal carotid artery from atherosclerosis, the occluded vessel can sometimes be recanalized with low morbidity. In addition, endovascular access to the intracranial circulation can be expedited by using the recanalized internal carotid artery.     

Penetrating trauma of the internal carotid artery

OBJECTIVE: To assess management of penetrating internal carotid artery (ICA) injuries. DESIGN: Retrospective review of institutional protocol. SETTING: Level 1 trauma center in a major urban area. PATIENTS: Sixty-one patients with penetrating ICA injuries. INTERVENTIONS: In the period 1975 to 1987 (group 1; n = 36), management was based on individual surgeons' preferences. Between 1988 and 1995 (group 2; n = 25), an algorithm was employed: (1) hemodynamically stable patients with suspected ICA injuries underwent a diagnostic angiography; (2) surgically accessible injuries were reconstructed regardless of neurologic status with 2 exceptions: (a) neurologically intact patients with ICA occlusion were treated by anticoagulation and mild pharmacological hypertension and (b) minimal nonocclusive injuries were managed nonoperatively and followed up by serial angiography or duplex ultrasonography; and (3) heparinization, shunting, and completion angiography were employed. MAIN OUTCOME MEASURES: Neurologic status at admission and discharge were compared by the Fisher exact test. RESULTS: In group 1, 24 patients (67%) presented neurologically intact, and 12 (33%) with a deficit. Sixteen injuries were managed nonoperatively, 14 were repaired, and 6 were ligated. At discharge 6 (17%) were improved, 24 (66%) were unchanged, 6 (17%) were worse. Four patients (11%) died of cerebrovascular causes. In group 2, 19 patients (76%) presented neurologically intact, and 6 (24%) with a deficit. Eleven injuries were managed nonoperatively, 12 were repaired, and 2 were ligated. A death occurred in a patient who arrested, was admitted to the hospital in a coma, and died before ICA repair. CONCLUSIONS: Neurologic outcome after ICA injury is enhanced by an algorithm predicated on the liberal use of angiography, a predefined surgical approach, and selective observation.