FDG PET biomarkers for prediction of survival in metastatic melanoma prior to anti-PD1 immunotherapy.

Our aim was to analyse whether biomarkers extracted from baseline 18F-FDG PET before anti-PD1 treatment contribute to prognostic survival information for early risk stratification in metastatic melanoma. Fifty-six patients, without prior systemic treatment, BRAF wild type, explored using 18F-FDG PET were included retrospectively. Our primary endpoint was overall survival (OS). Total metabolic tumoral volume (MTV) and forty-one IBSI compliant parameters were extracted from PET. Parameters associated with outcome were evaluated by a cox regression model and when significant helped build a prognostic score. Median follow-up was 22.1 months and 21 patients died. Total MTV and long zone emphasis (LZE) correlated with shorter OS and served to define three risk categories for the prognostic score. For low, intermediate and high risk groups, survival rates were respectively 91.1% (IC 95 80-1), 56.1% (IC 95 37.1-85) and 19% (IC 95 0.06-60.2) and hazard ratios were respectively 0.11 (IC 95 0.025-0.46), P = 0.0028, 1.2 (IC 95 0.48-2.8), P = 0.74 and 5.9 (IC 95 2.5-14), P < 0.0001. To conclude, a prognostic score based on total MTV and LZE separated metastatic melanoma patients in 3 categories with dramatically different outcomes. Innovative therapies should be tested in the group with the lowest prognosis score for future clinical trials.

Targeted radionuclide therapy with RAFT-RGD radiolabelled with (90)Y or (177)Lu in a mouse model of αvß3-expressing tumours.

PURPOSE: The αvß3 integrin plays an important role in tumour-induced angiogenesis, tumour proliferation, survival and metastasis. The tetrameric RGD-based peptide, regioselectively addressable functionalized template-(cyclo-[RGDfK])4 (RAFT-RGD), specifically targets the αvß3 integrin in vitro and in vivo. The aim of this study was to evaluate the therapeutic potential of RAFT-RGD radiolabelled with ß(-) emitters in a nude mouse model of αvß3 integrin-expressing tumours. METHODS: Biodistribution and SPECT/CT imaging studies were performed after injection of (90)Y-RAFT-RGD or (177)Lu-RAFT-RGD in nude mice subcutaneously xenografted with αvß3 integrin-expressing U-87 MG cells. Experimental targeted radionuclide therapy with (90)Y-RAFT-RGD or (177)Lu-RAFT-RGD and (90)Y-RAFT-RAD or (177)Lu-RAFT-RAD (nonspecific controls) was evaluated by intravenous injection of the radionuclides into mice bearing αvß3 integrin-expressing U-87 MG tumours of different sizes (small or large) or bearing TS/A-pc tumours that do not express αvß3. Tumour volume doubling time was used to evaluate the efficacy of each treatment. RESULTS: Injection of 37 MBq of (90)Y-RAFT-RGD into mice with large αvß3-positive tumours or 37 MBq of (177)Lu-RAFT-RGD into mice with small αvß3-positive tumours caused significant growth delays compared to mice treated with 37 MBq of (90)Y-RAFT-RAD or 37 MBq of (177)Lu-RAFT-RAD or untreated mice. In contrast, injection of 30 MBq of (90)Y-RAFT-RGD had no effect on the growth of αvß3-negative tumours. CONCLUSION: (90)Y-RAFT-RGD and (177)Lu-RAFT-RGD are potent agents targeting αvß3-expressing tumours for internal targeted radiotherapy.

Remission of Merkel cell tumor after somatostatin analog treatment.

We recently treated one patient presenting with a disseminated non-operable Merkel cell carcinoma (MCC) by lanreotide (somatostatin analog), with a complete remission of the disease and a follow up of 17 months. We present in this paper a case report with a review of the utilization of somatostatin analogues in the treatment of MCC.

Non-conform diagnostic management of pulmonary embolism suspected patients is responsible for a higher risk of thrombotic event occurrence.

The aim of this 3-month follow-up prospective pragmatic study was to evaluate the implementation of a pulmonary embolism (PE) diagnostic strategy in clinical practice. One thousand and one hundred thirty-four consecutive in- and outpatients with clinically suspected PE were enrolled into a sequential diagnostic algorithm in which vascular medical unit plays a pivotal role in advising physicians and suggesting the most appropriate tests according to the diagnostic algorithm. In this observational study, patients that followed the proposed work-up were attributed to a so-called "conform group". Patients in whom diagnostic work-up was not according to protocol were attributed to a "non-conform group". Nine hundred and ninety-seven patients (87.9%) had a conform work-up, and 137 patients a non-conform work-up according to the proposed diagnostic algorithm. The non-conform work-up directly increased in relation to the age of the referred patients. PE was ruled out in 907 (80%) patients of whom 787 (86.8%) were in the conform group. Of the 797 patients who did not receive anticoagulant drugs, follow-up was obtained in 792 (99.4%). Among these patients, the incidence of acute thromboembolic events during the 3-month follow-up period was different in the group of patients that had a conform work-up (1%, [95% CI, 0.5-2.1%]) from the non-conform group patients (4.5%, [95% CI, 2-10.2%]. Therefore patients from the non-conform group have an independent increased risk to develop a thromboembolic event during the follow-up, adjusted odds ratio 3.3 [1.1-10, 95% CI]. Therefore we demonstrated that a non-conform diagnostic management strategy is associated with a higher risk of thrombotic event occurrence.

High frequency of bone/bone marrow involvement in advanced medullary thyroid cancer.

High hematological toxicity has been observed with anti-carcinoembryonic antigen radioimmunotherapy (RIT) in medullary thyroid carcinoma (MTC), suggesting metastatic bone involvement (BI). This retrospective study evaluated the rate of BI in MTC patients enrolled in two phase-I/II RIT trials using anti-carcinoembryonic antigen x anti-diethylenetriamine pentaacetic acid bispecific antibodies and [(131)I]di-diethylenetriamine pentaacetic acid hapten. Thirty-five patients underwent bone scintigraphy, bone magnetic resonance imaging (MRI), and post-RIT immunoscintigraphy (IS). IS performed in MTC patients was compared with IS conducted in 12 metastatic colorectal carcinoma (CRC) patients. Quantitative analysis of bone uptake was performed in three MTC and three CRC patients. In the MTC group, bone scintigraphy detected BI in 56.6% of patients, MRI in 75.8%, and IS in 88.6%. BI was confirmed by undirected (random) bone marrow biopsy, by bone surgery, or by two positive imaging methods in 74.3% of the patients. Sensitivity per patient of bone scintigraphy, MRI, and IS were 72.7, 100, and 100%, respectively. In contrast, IS visualized BI in only 33.3% of CRC patients; bone uptake was lower in CRC than in MTC patients. Bone MRI combined with post-RIT IS disclosed a much higher BI rate in advanced MTC than previously reported in the literature.

[Radioimmunotargeting: diagnosis and therapeutic use]. / Le radio-immunociblage: aspects diagnostiques et thérapeutiques.

Monoclonal antibodies labeled with a radionuclide make feasible the in vivo radioimmunotargeting of tumor cells. This targeting could be performed for diagnosis, using gamma emitters, or for therapeutic purpose when antibodies are labeled with beta- and in the future alpha-emitters. Diagnosis applications (tumor detection and caracterization), i.e. immunoscintigraphy, have been widely investigated during 20 last years. This technic appeared quite interesting, complementary of morphological imaging, and clinically useful, but difficult on a practical point of view because of several pharmacological and immunological limitations. For these reasons, despite several consequent improvements (especially two-steps or pre-targeting methods), immunoscintigraphy is currently not widely used; furthermore, other scintigraphic methods, mainly positron emission tomography with 18F-fluorodeoxyglucose, are efficient and easier to perform. On the other hand, knowledge of the biodistribution of radiolabeled antibodies allows the development of their therapeutic use, i.e. radioimmunotherapy, which represents a new method of cancer treatment. Radioimmunotherapy has several particular radiobiological and dosimetric aspects, which remain widely under investigation. Understanding of these aspects, together with a better delineation of the indications, allow to be really optimist concerning this new way of cancer treatment, as shown by clinical results that have been obtained in non Hodgkin's lymphoma. Radiolabeled immunoconjugates appears as a growing field in nuclear medicine, which sustains numerous preclinical and clinical studies.

Radioimmunotherapy in medullary thyroid cancer using bispecific antibody and iodine 131-labeled bivalent hapten: preliminary results of a phase I/II clinical trial.

The toxicity and therapeutic efficacy of escalating doses of anti-carcinoembryonic antigen x anti-N alpha-(diethylenetriamine-N,N,N',N''-tetraacetic acid)-In bispecific monoclonal antibody (F6-734) and iodine 131-labeled bivalent hapten were determined in a Phase I/II trial. A total of 26 patients with recurrences of medullary thyroid cancer documented by imaging and a rise in serum thyrocalcitonin were enrolled. Twenty to 50 mg of F6-734 and 40-100 mCi of 131I-hapten were injected 4 days apart. Quantitative scintigraphy was performed after the second injection for dosimetry estimations in eight cases. Clinical, biological, and morphological follow-up was carried out for 1 year after treatment. The mean percentage of injected activity per gram of tumor at the time of maximum uptake was 0.08% (range, 0.003-0.26%). The tumor biological half-life ranged from 3 to 95 days, and tumor doses ranged from 2.91 to 184 cGy/mCi. The estimated tumor-to-nontumor dose ratios were 43.8 x 53.4, 29.6 x 35.3, 10.9 x 13.6, and 8.4 x 10.0 for total body, red marrow, liver, and kidney, respectively. Grade III/IV hematological toxicity was observed in seven patients, most of them with bone metastases. Among the 17 evaluable patients, 4 pain reliefs, 5 minor tumor responses, and 4 biological responses with decrease of thyrocalcitonin were observed. Nine patients developed human anti-mouse antibody. Dose-limiting toxicity was hematological, and maximum tolerated activity was 48 mCi/m2 in this group of patients, most of whom had suspected bone marrow involvement. The therapeutic responses observed in patients mainly with a small tumor burden are encouraging for the performance of a Phase II trial with minimal residual disease.

Radioimmunotherapy of small cell lung carcinoma with the two-step method using a bispecific anti-carcinoembryonic antigen/anti-diethylenetriaminepentaacetic acid (DTPA) antibody and iodine-131 Di-DTPA hapten: results of a phase I/II trial.

As small cell lung carcinoma (SCLC) is frequently a widespread disease at diagnosis, highly radiosensitive and often only partially responsive to chemotherapy, radioimmunotherapy (RIT) would appear to be a promising technique for treatment. We report the preliminary results of a Phase I/II trial of RIT in SCLC using a two-step method and a myeloablative protocol with circulating stem cells transplantation. Fourteen patients with proved SCLC relapse after chemotherapy were treated with RIT. They were first injected i.v. with a bispecific (anti-carcinoembryonic antigen/anti-diethylenetriaminepentaacetic acid) monoclonal antibody (20-80 mg in 100 ml of saline solution) and then 4 days later with di-(In-diethylenetriaminepentaacetic acid)-tyrosyl-lysine hapten labeled with 1.48-6.66 GBq (40-180 mCi) of I-131 and diluted in 100 ml of saline solution. In patients receiving 150 mCi or more, circulating stem cells were harvested before treatment and reinfused 10-15 days later. Treatment response was evaluated by CT and biochemical data during the month before and 1, 3, 6, and 12 months after treatment. All patients received the scheduled dose without immediate adverse reactions to bispecific antibody or 1-131 hapten. Toxicity was mainly hematological, with two cases of grade 2 leukopenia and three cases of grade 3 or 4 thrombopenia. Body scanning 8 days after injection of the radiolabeled hapten generally showed good uptake at the tumor sites. Estimated tumor dose was 2.6-32.2 cGy/mCi. Among the 12 patients evaluated to date, we have observed 9 progressions, 2 partial responses (one almost complete for 3 months), and 1 stabilization of more than 24 months. Efficiency and toxicity were dose-related. The maximal tolerable dose without hematological rescue was 150 mCi. These preliminary results are encouraging, and dose escalation is currently continuing to reach 300 mCi. RIT should prove to be an interesting therapeutic method for SCLC, although repeated injections and hematological rescue will probably be required, as well as combination with other treatment modalities.

Can tumour marker assays be a guide in the prescription of bone scan for breast and lung cancers?

Considering the current need to improve cost-effectiveness in cancer patient management, a prospective study was undertaken in order to define the optimal combination of bone scan and tumour marker assays in breast and lung cancer strategies, as has been done in the case of prostate cancer. All patients with breast or lung cancer referred to the Nuclear Medicine Department of the Grenoble Teaching Hospital between December 1995 and April 1997 were included. A blood sample was drawn in each case for marker assay (CA15-3 or CEA and CYFRA 21-1) on the same day as the bone scan. Two hundred and seventy-five patients were included: 118 with lung cancer and 157 with breast cancer. With regard to lung cancer, no information useful for guiding bone scan prescription was obtained through CEA and CYFRA 21-1 assays. For breast cancer, the results suggest that in asymptomatic patients, a CA15-3 level of less than 25 U/ml (upper normal value chosen as the threshold) is strongly predictive of a negative bone scan; by contrast, high tumour marker levels are predictive of neoplastic bone involvement. When a doubtful bone scan is obtained in a patient with breast cancer, a normal marker level makes it highly probable that bone scan abnormalities are not related to malignancy.

Pretargeting with the affinity enhancement system for radioimmunotherapy.

The pretargeting technique referred to as the Affinity Enhancement System (AES) uses bispecific antibodies and radiolabeled bivalent haptens that bind cooperatively to target cells in vivo. Experimental and clinical data demonstrate that AES can deliver large radiation doses to tumor cells with high tumor to normal tissue contrast ratios and long activity residence time in tumors. Preliminary clinical results of radioimmunotherapy of medullary thyroid carcinomas and lung cancers look promising.

Potential use of radiolabeled antisense oligonucleotides in oncology.

Antisense oligodeoxynucleotides (ODNs) have great promise for therapy. Oligomers labeled with gamma-emitting radioelements have great promise for diagnosis. These radiolabeled oligomers can be used to identify the presence of a particular messenger RNA through simple external detection of radioactivity by means of scintigraphy. This review evaluates the progress in the development of antisense oligodeoxynucleotides for non-invasive imaging of chemoresistance. As nominated by H.N. Wagner at the final session of Nuclear Medicine congress in Denver, the deoxyribonucleic acid is "the molecule of the millennium".

Radioimmunodetection of medullary thyroid carcinoma using indium-111 bivalent hapten and anti-CEA x anti-DTPA-indium bispecific antibody.

UNLABELLED: Pretargeting labeled bivalent hapten with bispecific antibodies has proven feasible in the clinic, and our earlier results have suggested the technique may be very sensitive for detecting small recurrences and metastases. Medullary thyroid carcinoma (MTC) is an example where this technique may be the most useful since local recurrences and isolated metastases are removed surgically when detected, and thyrocalcitonin provides a specific and sensitive tumor marker. In our current study, we evaluated pretargeted immunoscintigraphy in a larger number of MTC patients. METHODS: Anti-carcinoembryonic antigen (CEA) x anti-diethylenetriaminepentaacetic acid (DTPA) indium bispecific antibody and 111In-labeled bivalent DTPA hapten were administered sequentially (4-5 days apart) to 44 patients with elevated circulating calcitonin after resection of primary MTC. Immunoscintigraphy was performed 2, 5 and 24 hr after hapten injection and, when necessary, at longer time intervals. When available, a handheld gamma probe was used during surgery. RESULTS: Fifteen patients had known tumor sites before immunoscintigraphy. Tumors were imaged in 12 (80%) of these patients, including 3 with liver metastases. Five unknown tumor sites were detected. For the 29 patients with occult disease, immunoscintigraphy detected high-activity uptake sites in 21 patients (72%), including 5 in the liver. Twelve were confirmed by surgery, 1 by guided morphologic imaging and 1 by venous catheterization. There were 2 false-positive patients. The other 5 patients have not yet been confirmed. All detected liver metastases were high-activity uptake areas. Radioimmunoguided surgery was used in 14 patients. It was considered helpful by the surgeon in 12 patients, including 4 patients where it determined the resection of small, not palpable nor visible, tumor-involved lymph nodes. Surgical resection resulted in a significant decrease (8 patients) or normalization (1 patient) of circulating calcitonin and CEA. CONCLUSION: This technique affords high sensitivity and specificity for detecting small tumor lesions including liver metastases. Its use for immunoscintigraphy and guided surgery should improve the therapeutic management of recurrent MTC.

[Positron emission tomography (PET) and (F-18)-fluorodeoxyglucose in (FDG) in cancerology]. / Tomographie par émission de positons (TEP) et [F-18]-fluorodésoxyglucose (FDG) en cancérologie.

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) is a scintigraphic imaging technique undergoing a rapid growth in the field of oncology. The constant progress of the detectors, either CDET or PET dedicated cameras, allows to obtain in routine conditions images with a 5 mm spatial resolution. Absolute tracer uptake quantification is also possible, which allows to evaluate objectively therapy efficacy. The mechanisms of FDG tissular accumulation are now better understood. Increase of glycolysis and of transmembrane transport of glucose seems to be at the origin of the high tumorous accumulation of FDG. The main current oncologic application of FDG PET is the diagnosis of malignancy of the isolated pulmonary nodules, with a sensitivity of more than 95%, and in the staging of lung cancer where PET shows higher performances than conventional imaging. The same stands in cutaneous melanoma and for malignancies of the digestive tract, either in colorectal, pancreatic or esophageal localizations. In colorectal cancers, the role of PET has for long being recognized in the differential diagnosis between recurrence and postoperative fibrosis. In the head and neck tumors, FDG also allows to differentiate between recurrence and postradiation necrosis. In lymphoma, the most suitable site for biopsy can be identified on a PET scan and therapy efficacy can also be assessed. In breast cancer, the detection of metastases seems to be possible with FDG. In brain and thyroid cancers, the role of FDG PET remains to be further determined. The low uptake of FDG in prostate cancer metastasis is not in favor of its use in this indication. In conclusion, the indications of FDG PET in oncology are now becoming more precise and it can be expected that clinical PET centers will soon appear in France.

Two-step immunoscintigraphy for non-small-cell lung cancer staging using a bispecific anti-CEA/anti-indium-DTPA antibody and an indium-111-labeled DTPA dimer.

UNLABELLED: Immunoscintigraphy (IS) using anti-CEA F(ab')2 monoclonal antibody (MAb) is useful for improving mediastinal staging of nonsmall cell lung cancer (NSCLC), but the technique was limited because of an insufficient contrast between tumor and normal tissues. The aim of this study was to determine if the method could be improved by a two-step method which uses a bispecific anti-CEA/anti-di-DTPA antibody (Bs-MAb) and 111In-labeled di-DTPA-tyrosyl-lysine bivalent hapten. METHODS: Twelve patients were intravenously given a 30 min Bs-MAb infusion (0.1 mg/kg). Four days later, they were injected intravenously with 0.1 microgram/kg hapten labeled with 185 MBq 111In (5 mCi). Images were recorded immediately and 6 and 24 hr after hapten injection. A pharmacokinetic analysis was performed. Surgery was performed 3 days after 111In-hapten injection, and samples of tumor and normal tissues were collected for immunohistochemical and biodistribution studies. IS results were classified as true-positive (TP), false-positive (FP), true-negative (TN) or false-negative (FN) according to the surgical data. RESULTS: Primary tumors were visualized in nine patients. The contrast was excellent, generally higher than that obtained with direct labeling of anti-CEA. In the mediastinum, IS results were (after surgery) five TN, two TP and one FP. One case remains undetermined. The FP result was due to a Bs-MAb uptake in intrapulmonary lymph nodes. IS was in agreement with preoperative staging in six of these nine patients and discordant in three. CONCLUSION: Our study confirmed that the two-step method with a bispecific antibody could greatly improve the performances of IS for lung cancer staging.

Effects of preoperative intentional hemodilution on the extravasation rate of albumin and fluid.

OBJECTIVE: To evaluate the effects of preoperative intentional hemodilution with 4% albumin solution on the extravasation rate of intravascular albumin and fluid in surgical patients. DESIGN: A prospective, randomized, clinical study. SETTING: University teaching hospital. PATIENTS: Two groups (control group [group 1] and hemodiluted group [group 2]) of 13 healthy patients were studied during a long-term (>4 hrs) surgical procedure. INTERVENTIONS: Autologous technetium-99m (99mTc)-labeled red blood cells and indium-oxine ((111)In)-labeled human serum albumin were injected intravenously during anesthesia at T = 0 min in the two groups for the determination of total blood volume and albumin diffusion space, respectively. In addition, body tetrapolar electrical impedance was used to assess extracellular fluid volume. In the hemodiluted group (group 2), 15 mL/kg of blood was withdrawn over 30 mins (T = 20 mins to T = 50 mins) and simultaneously replaced by an equal volume of 4% albumin solution (0.6 g/kg). MEASUREMENTS AND MAIN RESULTS: The albumin diffusion space, the colloid oncotic pressure, the plasma albumin concentration and the electrical impedance were measured before (T = 10 mins) and after (T = 60, 120, and 240 mins) hemodilution. Urine was collected from T = 10 mins to T = 240 mins. The total blood volume was calculated at T = 10 mins. No differences in the initial values were found between the two groups. In group 2, hemodilution (hematocrit 30 +/- 3%) resulted in a steeper increase in the albumin diffusion space (p < .05) and a progressive decrease in the body electrical impedance (p < .05). The extravasation rate of albumin was 0.052 +/- 0.007 mL/kg/min in group 2 vs. 0.038 +/- 0.020 mL/kg/min in group 1 (p < .05). The value of calculated plasma volume at T = 0 min did not shown any difference between the two groups. This value was then lower than expected in group 2, corresponding to a loss of plasma volume of >3 mL/kg. Urine output was significantly lower in group 2 than in group 1 (0.7 +/- 0.4 vs. 1.4 +/- 1.0 mL/min, respectively; p < .05). A comparable decrease in colloid oncotic pressure and in plasma albumin concentration was observed in both groups. CONCLUSIONS: These results suggest that preoperative hemodilution using 4% albumin on a 1:1 volume basis for blood substitution during a prolonged surgical procedure with reduced blood losses enhances the extravasation rate of albumin and fluid to the interstitial tissues, impeding the maintenance of isovolemia. These findings support the use of a volume of infused colloid solution higher than that of withdrawn blood during preoperative hemodilution.

[Evaluation of the diagnostic usefulness of CA125 immunoscintigraphy for ovarian carcinoma follow-up after treatment: contribution of this technique in Grenoble University Medical Center]. / Evaluation de l'utilité diagnostique de l'immunoscintigraphie au CA.125 dans le suivi des carcinomes du revêtement épithélial de l'ovaire après traitement: apport décisionnel de la technique au CHU de Grenoble.

Immunoscintigraphy using indium-111-labeled OC125 monoclonal antibody F(ab')2 fragments is a technic complementary of morphological imaging (i.e. ultrasonography and computed tomography). It allows early detection of recurrences of ovarian carcinomas. We performed immunoscintigraphy 30 times in 26 patients who previously underwent radical treatment for ovarian carcinoma, and were suspected to have a recurrence. Our purposes were appreciation of diagnostic accuracy of the method, and above all its impact on clinical decisions and evolution of the patients. There were, after reevaluation of the results, 18 true positives, 7 true negatives, 3 false negatives and 2 false positive cases (sensitivity 85.7%, specificity 77.8%). Bayesian analysis showed positive and negative predictive values of 86% and 87% when probability of recurrence a priori was 50%, and 80% and 58% when probability of recurrence a priori was 70%. The result of immunoscintigraphy contributed to clinical decisions in 24 cases out of 30, and led to a correct decision for the patient in 21 cases. Conversely, for the 6 cases in which the result has not been considered, to take this result into account would have been beneficial in 4 cases, but harmful in 2. Finally, survival tended to be longer when immunoscintigraphy was negative, which could be associated with a better prognosis. We conclude that OC125-immunoscintigraphy may be useful for ovarian carcinoma follow-up and may contribute to a better therapeutic strategy.

[Pulmonary scintigraphy in the diagnosis of pulmonary embolism]. / La scintigraphie pulmonaire dans le diagnostic d'embolie pulmonaire.

Venous thromboembolism (VTE) and pulmonary (PE) are difficult to diagnose. Pulmonary scintigraphy is a key investigation in the diagnosis of PE due to its innocuity and high sensitivity. A complete examination requires analysis of ventilation and perfusion (with at least four different views). The sensitivity of the method is excellent and a normal perfusion pulmonary scintigraphy excludes the diagnosis (10-15% of cases). On the other hand, the specificity is not nearly as good as only 10 to 15% of scintigraphies show changes which make the diagnosis of PE certain. In about 2 out of 3 cases, pulmonary scintigraphy alone is not decisional and only allows an estimation of the probability of PE this investigation must be integrated in the diagnostic strategy based on the "a priori" clinical probability, non invasive venous exploration and, in second intention, pulmonary angiography. The authors report the diagnostic strategy defined in Grenoble University hospital after multidisciplinary concertration. An evaluation in 103 patients with suspected PE showed a divergence from this diagnostic protocol in 38% of cases. However, when the protocol is respected, a therapeutic decision can be taken in 73% of cases based on clinical assessment scintigraphy and Doppler ultrasonography. Therefore, the diffusion and observance of these diagnostic strategies should be improved. In these conditions, pulmonary scintigraphy plays an essential role in the diagnosis of PE. The necessity of a control pulmonary scintigraphy and the value of systematic scintigraphy in the presence of proximal venous thrombosis are also discussed.