Doppler examination

Doppler examination can be carried out during an ultrasound investigation. Doppler is used to measure the direction and speed of blood flow in vessels and the presence of any collateral vessels. In portal hypertension, the collateral vessels can have either flow in both directions or a total reversal of flow. 

Assessment of vascularity can be useful in differentiating benign and malignant breast lesions using color Doppler examination. However, some neoplasms have low blood flow and Doppler may be suboptimal. In these cases, ultrasound contrast may be beneficial. In a phase II/III, multicenter, randomized study 220 patients... 

The safety of Sono Vue as an intravenous bolus injection of 0.3, 0.6, 1.2, or 2.4 ml in transcranial Doppler examination of the cerebral arteries has been investigated in 40 patients (mean age 64 years) (19). The interval between each dose was at least 10 minutes or until total disappearance of the contrast effect from the previous dose. Eight patients reported 12 adverse events. There were no serious adverse events and no patient withdrew because of an adverse event. The most common adverse events were pain at the injection site, headache, and a feeling of warmth all were mild. 

Doppler ultrasound is the initial modality of choice to differentiate venous malformations from other vascular abnormalities. Ultrasound is performed with a high-frequency linear array transducer (5-12 MHz). On grey-scale images, venous malformations appear as compressible hypoechoic or heterogeneous lesions [15,16] (Fig. 2.2a-c). Calcifications (demonstrated in less than 20% of cases), are quite specific of venous malformation anechoic channels can be seen. Doppler examination displays a monophasic low-velocity flow (Fig. 2.3). In 20% of venous malformations, no flow can be demonstrated. Dynamic manoeuvres such as Valsalva or manual compression are sometimes necessary to induce a visible Doppler flow. 

In children with spontaneous hematuria, US can rule out urolithiasis or tumor. In renal failure, US can exclude renal vein or artery thrombosis (Laplante et al. 1993). Doppler US can confirm diagnosis and help follow-up of hemolytic-uremic syndrome (Patriquin et al. 1989). In children with palpable abdominal mass, US and plain film of the abdomen are usually sufficient to establish the diagnosis, which is then confirmed by enhanced CT or MRI. In patients with arterial hypertension, B-mode US can detect renal scar, hypoplasia, or nephropathy. Then, Doppler examination of renal vessels and parenchyma can orient diagnosis toward vascular cause. Renal angiography remains the reference examination (Garel et al. 1995). 

In our institution, US-guided renal biopsies are performed under general anesthesia in the operating room. The child is in the prone position. Conventional US is performed first targeting the lower pole of the right kidney. Two or three fragments are taken in the most peripheral location. Post-procedural US is performed. A second US examination is performed 24 h later, before the child is allowed to leave the hospital. The risk of post-procedural arteriovenous fistula justifies a color-Zpower-Doppler examination of the biopsy site. 

Patriquin H (1991) Doppler examination of the kidney in infants and children. Urol Radiol 12 220-227 Patti G, Menghini ML, Tordini AR et al (2000) The role of the renal resistive index ratio in diagnosing obstruction and in the follow-up of children with unilateral hydronephrosis. BJU Intern 85 308-312 Peppas DS, Skoog SJ, Canning DA et al (1991) Nonsurgical management of VUR in complete ureteral duplication. JUrol 146 1594-1595... 

Several studies have shown that the use of color or power Doppler may increase the detection rate of the method to 85%. The contribution of Doppler is based on the lack of vascularization of diseased areas due to inflammatory edema and ischemic lesions (Figs. 15.1c 15.5b, 15.6). The problem with Doppler techniques is that they require good cooperation from quiet patients therefore, in some institutions, sedative drugs are administered to the patients before a Doppler examination (Eggli and Eggli 1992 Winters 1996 Dacher et al. 1996 Halevy etal.2004). 

Briscoe DM, Hoffer FA, Tu N et al (1993) Duplex Doppler examination of renal allografts in children correlation between renal blood flow and clinical findings. Pediatr Radiol 23 365-368... 

Schwartz M, Weaver F, Yellin A et al (1993) The utility of color Doppler examination in penetrating extremity arterial trauma. Am Surg 59 375-378... 

In some cases color/power Doppler examinations do not show the characteristic spoke-wheel pattern but vessels randomly distributed in the lesion and at its periphery, without a clear central artery. In these lesions, the detection of an arterial Doppler signal with high diastolic flow can help in differentiating FNH from malignant lesions, such as hypervascular metastases and HCCs. 

Renal parenchyma infection may be seen as an increased graft volume and/or areas of decreased or increased echogenicity with decreased flow on color Doppler examination (Fig. 3.11). The power... 

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