Fabio Pretolesi

Power Doppler sonography: clinical applications

OBJECTIVE Color Doppler imaging (CD) has had a great impact on ultrasonography (US). This technique depicts local flow by encoding an estimate of the mean Doppler frequency shift at a particular position in color. However, the choice of the mean frequency shift as the parameter for representing flow in color Doppler is somewhat arbitrary. Power Doppler ultrasound is a technique that encodes the power in the Doppler signal in color. This parameter is fundamentally different from the mean frequency shift. The frequency is determined by the velocity of the red blood cells, while the power depends on the amount of blood present. Providing an image of a different property of blood flow, power Doppler has shown several key advantages over colour Doppler, including higher sensitivity to flow, better edge definition and depiction of continuity of flow. In this paper we review the results of power Doppler clinical studies. MATERIALS AND METHODS All relevant information available in the literature on the potential clinical applications of this technique was revised to give a detailed survey. RESULTS The increased flow sensitivity and better vascular detailing of power Doppler have been used to detect flow presence and characteristics in vessels that are poorly imaged with conventional color Doppler. The improved depiction of tissue vasculature has shown potential advantages, especially in some areas, such as the cortex of native kidneys and renal allografts, the prepuberal testis, the infant hip and the bowel wall, in which color Doppler is not sensitive enough to detect clinically important, slow and poor flow in small vessels. In inflammatory conditions, power Doppler was valuable in depicting increased flow in vessels that are dilated because of inflammatory response. In this field, advantages have been reported in acute cholecystitis and in inflammatory states of musculoskeletal tissues. The higher sensitivity to slow flow and the improved detailing of the course of tortuous and irregular vessels made power Doppler a promising technique to image intratumoral vessels and, thereby, to ameliorate the accuracy of color Doppler in predicting the likelihood of benign versus malignant nature of nodules. Specific flow patterns, missed at color Doppler studies, have been indicated with power Doppler in some tumors of the liver and breast. In different settings, power Doppler also permitted to monitor serial blood flow changes after therapy and to display them as color intensity, allowing the observer to distinguish flow changes. CONCLUSION Although the actual role of power Doppler in changing patient management has not been assessed yet, this technique can depict flow which was previously undetectable, and thus permits an easier and more confident diagnosis in body regions where the ultrasound signal is weak because blood vessels are small.

Energy and Nitrogen Absorption after Biliopancreatic Diversion

Background: The strict long-term weight maintenance in good nutritional conditions observed after biliopancreatic diversion (BPD) needs to be explained. Materials and Methods: 15 operated subjects were maintained at an isoenergetic and isonitrogenic diet as similar as possible to their usual diet. Apparent absorption (AA) of energy, fat, nitrogen and calcium was calculated subtracting the fecal content, measured directly, from the oral intake, derived from tables.The alimentary protein absorption was directly determined by I125 albumin oral administration. Results: Mean AA for energy and fat was 57% and 32%, respectively; AAs were unrelated as absolute value and negatively associated as percent of the intake with the energy and fat intake. I125 intestinal absorption was 73%, while nitrogen percent AA was 57%, indicating higher than normal loss of endogenous nitrogen. Calcium AA was 551 mEq/day, 26% of the intake. A positive correlation between nitrogen and calcium AA as absolute values and alimentary intake was observed, while there was no correlation when AA were considered as per cent of the intake. Conclusions: For energy and fat, an increase in intake corresponds to an increase in percent malabsorption, so that the absolute amount absorbed tends to remain constant, accounting for the excellent weight maintenance observed following BPD. This was confirmed by a long-term hypernutrition study after BPD. On the contrary, for nitrogen and calcium, the percent absorption tends to remain constant when intake varies, so that an increase in alimentary intake results in an increased absolute amount absorbed.

Doppler evaluation of intrathyroid arterial resistances during preoperative treatment with Lugol's iodide solution in patients with diffuse toxic goiter

BACKGROUND The aim of this study was to ascertain the utility of echo-Doppler in the analysis of the low resistance thyroid vascularization in diffuse toxic goiter (DTG), and the effectiveness of Lugols solution (iodine-iodide solution) in patients undergoing thyroidectomy. STUDY DESIGN Twenty-five patients with diffuse toxic goiter were evaluated and compared with 19 normal subjects. Patients were treated with increasing doses of Lugols solution 2% for 7 days until a total dose of 75 mg of iodine was given. Echo-Doppler was performed on the last day of treatment, 12 hours before operation. RESULTS Mean basal Doppler Resistance Index (RI) of intrathyroid arterial flow was significantly lower in patients with DTG compared with normal controls (0.4718 +/- 0.0625 versus 0.55 +/- 0.05, range: 0.472 to 0.643; p = 0.008). Moreover, the RI was significantly increased in patients with DTG after Lugols solution (+16.46 +/- 10.22%, range: -2.59 to +39.97; p< 0.0005). CONCLUSIONS Echo-Doppler RI allowed documenting lower arterial resistances within the thyroid gland in patients with DTG. The use of preoperative Lugols solution therapy induces normalization of those changes for safer thyroidectomy.

Duplex Doppler analysis of interlobular arteries in transplanted kidneys

Abstract. The aim of our study was to analyze changes in spectral Doppler waveforms between interlobar and interlobular arteries in renal transplants and to determine whether sampling location at interlobular level can be suitable for intrarenal resistive index (RI) measurements. Paired series of spectral tracings from interlobar arteries and respective interlobular branches were obtained in 62 consecutive renal transplants at 6.5-MHz Doppler frequency. The values of peak systolic velocity (PSV), end diastolic velocity (EDV) and RI were significantly (P < 0.01) reduced when calculated at interlobular level. In 38 % of cases, an interlobar RI higher than 0.70 corresponded to a normal interlobular RI. The values of PSV, EDV, and RI did not differ significantly at interlobular level between allograft subsets with normal and elevated serum creatinine level. Both intra- and interobserver variation were higher at interlobular than at interlobar level when performing the RI. During a conventional study of renal vasculature, an underestimation of abnormal RI findings can be expected from the incidental evaluation of interlobular tracings. We recommend sonologists to pay attention in accurately locating the sample volume at interlobar–arcuate level when evaluating intrarenal RI.

Possible Malignant Transformation of Benign Lymphoepithelial Parotid Lesions in Human Immunodeficiency Virus-Infected Patients: Report of Three Cases

Benign lymphoepithelial parotid lesions (BLL) are intraparotid pathological changes that are commonly thought to be an early manifestation of human immunodeficiency virus (HIV) infection. It is not well known whether BLL may undergo malignant transformation into B cell lymphoma and may therefore be a sort of precancerous lesion. We report 3 cases of possible malignant transformation of BLL in HIV-infected patients.

Intragastric balloon for morbid obesity causing chronic gastric dilatation.

Abstract We describe the radiographic findings observed in a morbidly obese and diabetic patient with an intragastric air-filled balloon introduced as a therapeutic measure to reduce food intake. The balloon was associated with chronic gastric dilatation and had to be removed 3 months after insertion. However, together with diet and behavioural therapy, it proved effective in reducing body weight and ameliorating glycaemic control. Although rarely used, intragastric balloons for the treatment of morbid obesity are still encountered in radiological practice. Radiologists must be able to recognize them and to understand their complications.

Radiology of Patients with Vertical Banded Gastroplasty

Background: The authors evaluated the usefulness of routine traditional radiology in the management of patients submitted to VBG. Methods: Radiological findings in 65 subjects who had undergone VBG were evaluated. Post-surgical clinical and radiological examinations were performed 3 days, 1, 4 and 12 months after surgery. Upper GI symptoms, gastroesophageal imaging and 80% solid meal pouch emptying time were recorded. Results: The routine postoperative study, in the absence of clinical symptoms, showed no unsuspected complication in any patient, both in the early and in the late postoperative period. There was no significant correlation at 4 and 12 months between emptying time and duration of satiation, emptying time and percent excess weight loss (%EWL), and duration of satiation and %EWL. Conclusions: Traditional radiological studies can be safely omitted from both the immediate postoperative period and from the long-term follow-up in asymptomatic VBG patients. The studies were not helpful in understanding functional changes leading to weight loss after VBG.

US imaging and color Doppler in patients undergoing inhibitory therapy with calcitriol for secondary hyperparathyroidism.

The aim of this study was to evaluate the changes in volume, structure, and flow pattern of parathyroid glands in uremic patients with secondary hyperparathyroidism treated with long-term intravenous calcitriol (CTL) therapy. Ultrasonography was used to follow-up volume changes occurring in 18 enlarged glands in 11 patients during an 18-month period; in 6 of these cases, 11 glands were followed-up also with color-Doppler to monitor variations in flow pattern. Vascularization was classified using three grades: grade 0=no color signal; grade I=vessels covering less than 50% of glandular cross-sectional area; grade II=vascular signals covering more than 50% of glandular cross-sectional area. No significant changes in volume were demonstrated during the 18 months of follow-up. On the contrary, significant decrease in flow was observed with almost complete disappearance of color-Doppler signals. This finding related well with the observed decrease in parathormone blood levels. Lack of volume changes during medical therapy demonstrates the inability of US alone to monitor the effect of this treatment on the parathyroid glands. Conversely, the observed intraglandular flow reduction indicates the possibility to use color Doppler to monitor the effects of CLT in uremic hemodialyzed patients with secondary hyperparathyroidism. This imaging procedure can be proposed for follow-up of the response of the parathyroid glands to therapy.

Pouch diverticula after vertical-banded gastroplasty

Purpose.Diverticula of the proximal gastric pouch are rare after vertical-banded gastroplasty (VBG) for morbid obesity. We report the radiographic findings observed in a series of 12 patients with pouch diverticula.Materials and methods.Lesions were found along the posteromedial wall of the proximal gastric pouch and ranged in size from 10 to 25 mm. Only two patients were symptomatic at the time of diagnosis; in most cases, diverticula were discovered during studies performed as part of the standard follow-up protocol. Diverticula were followed up in 7/12 cases, and four showed slight enlargement over a period ranging from 14 to 53 months.Results.The presence of diverticula was not correlated with symptoms, postoperative weight loss, or clinical history, and no differences in long-term complications were demonstrated between VBG patients with diverticula and those without them.Conclusions.We do not believe these lesions to be clinically important; at present, our patients are no longer followed up for this problem and undergo diagnostic examinations only if and when they develop symptoms.

Crohn disease obstruction of the biliopancreatic limb in a patient operated for biliopancreatic diversion for morbid obesity

Although rare, patients with biliopancreatic diversion for morbid obesity will be subject to obstruction of the biliopancreatic limb. This condition is commonly due to postoperative adhesions and intussusception and usually presents with misleading clinical and radiographic features that can delay the diagnosis and the treatment. We recently encountered a patient with obstruction of the biliopancreatic limb due to involvement from Crohn disease. We report this case to highlight the clinical and imaging findings of this rare condition.