[Comparison between scintigraphy, B-mode, and power Doppler sonography in acute pyelonephritis in children]. / Imagerie comparative entre techniques scintigraphique et echographiques en mode B et Doppler energie dans la pyelonéphrite aigüe de l'enfant.

PURPOSE: Comparing Power Doppler imaging versus technetium-dimercapto-succinic-acid (Tc-DMSA) scintigraphy in acute pyelonephritis of childhood. INCLUSION CRITERIA: First episode of urinary tract infection, clinical and biological findings suggesting an upper lesion, absence of urological malformation or obstruction, absence of reflux (or vesico-ureteral reflux inferior to grade 3). Number of patients: 49, length of the study: 26 months (from November 95 to January 98). METHODS: Tc99m-DMSA scintigraphy (after five days), B mode and Power Doppler imaging (on the day of admission or the following day). Systematic cystography (day 5 to day 30). RESULTS: In terms of positive diagnosis, scintigraphy was superior to Power Doppler, and the latter was superior to B mode ultrasonography. Sensitivity (scintigraphy being the gold standard) was equal for both B mode and Power DopplerUS imaging, but combined Power Doppler and B mode US provided improved results. CONCLUSION: Currently, the results with Power Doppler imaging are insufficient to replace DMSA scintigraphy. However, Power Doppler is a good complement to B mode US.

[Diagnostic value of echocardiography and thoracic spiral CT angiography in the diagnosis of acute pulmonary embolism]. / Valeur diagnostique de l'échographie cardiaque et de l'angioscanner thoracique hélicoïdal pour le diagnostic de l'embolie pulmonaire aiguë.

The objective of this study was to define the limits of echocardiography and to evaluate thoracic spiral CT angiography (TSCTA) for the diagnosis of pulmonary embolism (PE). One hundred twelve consecutive patients, hospitalised for suspected PE, were included in this prospective study. All were investigated by pulmonary ventilation-perfusion scintigraphy (Sc) and 50 had a high probability of PE on this examination. Sc was normal in 22 patients. Forty patients were excluded because of an intermediate probability. In 50 patients with PE confirmed on Sc, transthoracic echocardiography (TTE) showed only indirect evidence of PE (intracavitary thrombus in 4% of cases). TSCTA demonstrated PE in 82% of cases and did not show any thrombus image when Sc was normal. Its negative predictive value was therefore 70% and its positive predictive value was 100%. Its sensitivity varied according to degree of perfusion defect (96% in the case of lobar lesion, 66% in the case of segmental lesion and 16% for a subsegmental lesion). Multidimensional transoesophageal echocardiography (TOE), performed in 37 of the 50 patients with PE, only revealed thrombi in the pulmonary tree in 3 patients (8%), all presenting severe PE. No thrombus was visualized on TOE in patients with non-serious PE. All thrombi observed on TOE were also demonstrated by TSCTA. In conclusion, TTE usually provides only indirect signs of PE. TOE has a poor diagnostic sensitivity for PE. TSCTA has a better sensitivity than TOE for the detection of thrombi in the pulmonary artery trunk and proximal centimetres of its two branches, but normal CT angiography cannot exclude a distal PE.

Steady-state captopril renography: continuous monitoring of the captopril-induced increase in 99mTc-MAG3 mean parenchymal transit time in renovascular hypertension.

Steady-state captopril renography (SSCR) is an original technique for assessing the captopril-induced increase in technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) mean parenchymal transit time (MPTT) in kidneys affected with functional renal artery stenosis (RAS). The steady-state parenchymal activity achieved by constant infusion of 99mTc-MAG3 is directly linked to the MPTT of the radiopharmaceutical. This steady-state parenchymal activity was continuously monitored from 15 min before to 60 min after a single dose of captopril in order to detect possible disruption of the steady state. SSCR was performed in 11 hypertensive patients with unilateral RAS and in two with RAS of a solitary kidney before renal revascularization (RR). In four of these patients, an additional SSCR was performed after RR. Of the ten patients whose hypertension was cured or improved by RR, one presented an uninterpretable SSCR and six presented a positive SSCR on the affected side. Control SSCR performed in four of these six patients was bilaterally negative. SSCR was also bilaterally negative in the three patients who showed no blood pressure response to RR. These preliminary results tend to indicate that, in spite of the stability of pre- and post-captopril hydration and data acquisition conditions allowed by this steady-state technique, the sensitivity is lower than expected. However, the reason for the false-negative results does not seem to be inherent to SSCR.

Anatomical data fusion for quantitative reconstruction in myocardial tomoscintigraphy using a spline model of the thorax organs.

We present the fusion of anatomical data as a method for improving the reconstruction in single photon emission computed tomography (SPECT). Anatomical data is used to deduce a parameterized model of organs in a reconstructed slice using spline curves. This model allows us to define the imaging process, i.e., the direct problem, more adequately, and furthermore to restrict the reconstruction to the emitting zones. Instead of the usual square pixels, we use a new kind of discretization pixel, which fits to the contour in the region of interest. In the reconstruction phase, we estimate the activity in the emitting zones and also the optimum parameters of our model. Concentrating on the left ventricular (LV) wall activity, the simulation and phantom results show an accurate estimation of both the myocardial shape and the radioactive emission.

99Tcm-HMPAO-labelled leucocyte scintigraphy in suspected chronic osteomyelitis related to an orthopaedic device: clinical usefulness.

Thirty-five patients with suspected chronic osteomyelitis related to an orthopaedic device had 50 99Tcm-HMPAO-labelled leucocyte scans (LS). The scan appearances were compared with the bacteriological or clinical results and gave a sensitivity and specificity of HMPAO-LS of 83 and 100%, respectively. Bacteriological examination is often inaccurate in the diagnosis of osteomyelitis and therefore we assessed the clinical utility of HMPAO-LS. When the clinical, biological and radiological data were clearly suggestive of osteomyelitis (16/50) LS was unhelpful or even misleading when falsely negative (3/16). When the clinical, biological and radiological data were poorly suggestive of osteomyelitis (20/50) or conflicting (14/50) LS was misleading in only one patient (false negative). It is concluded that HMPAO-LS should only be performed to assist in the diagnosis of chronic osteomyelitis when there is no preexisting strong suspicion based on clinical, biological and radiological signs.

A new unidirectional moving whole body scanner: comparative study of performances.

A new whole-body unidirectional moving scanner was built using a single large bar crystal, 12 photomultipliers on its top, and a delay line system to compute the X coordinate. Motion is required in only one direction on the Y-axis, and a special collimation is adapted in order to equal the X and Y performances of the detector. The performances of this detector (C.G.R. Scanicamera) (SC) were compared under the same conditions with those of a moving rectilinear scanner (R.S.) (Ohio Nuclear F 84 dual-head scanner, 12.5 cm crystal) and with an Anger gammacamera equipped with its whole body attachment (W.B.C.) Nuclear Chicago Pho Gamma III H.P.). The general impression is that this new whole-body unidirectional moving scanner is a very convenient device for whole body studies and can also be used for large scintigraphies.