Immunoscintigraphy with 131I or 111In Labelled OC 125 F(ab')2 Fragments in Patients with Ovarian Carcinoma

To evaluate the clinical usefulness of immunoscintigraphy with OC 125 in ovarian carcinoma, we studied 25 patients suspected of having ovarian carcinoma or in follow-up after surgery. Fourteen patients were studied with 131I-OC 125 F(ab')2 and 11 with 111In-OC 125 F(ab')2. No differences were observed with the use of either radionuclide.

Global diagnostic indexes obtained were S = 100%, Sp = 44,5% and A = 81%. The low specificity obtained was remarkable: 5 false positive results in two uterine myomas, one abscess, one follicular cyst and one granulation tissue scar. On the other hand, all lesions of ovarian carcinoma were detected. Analysis of the evolution of tumor/background (T/B) uptake ratios from the first to the second day of exploration revealed a tendency for the ratio to diminish significantly (> 15%) in false positive cases with the exception of the abscess while this did not happen in true positive cases, with the exception of a regional recurrence. Analysis of T/B ratio variations could contribute towards elevating the test's specificity.

[Meta-analysis of the diagnostic performance of 18F-FDG PET in renal cell carcinoma]

AIM

Renal cell carcinoma is the most frequent solid kidney tumor. At present, PET is not the imaging test of choice, the helical CT being the best method to assess these patients. The aim of the study was to perform a meta-analysis of the literature to evaluate the performance and accuracy of 18F-FDG PET in the detection of primary disease, recurrence and metastasis of renal cell carcinoma.

MATERIALS AND METHODS

A systematic search was done of the available literature in primary and secondary databases published until October 2004 indexed in MEDLINE and CANCERLIT. Exclusion/inclusion criteria were applied. Their quality was evaluated using the Flynn criteria and joint estimators of sensitivity (S), specificity (Sp), likelihood ratios (LR), diagnostic odds ratio (DOR) and summary ROC (SROC) curve were obtained. The presence of the threshold effect was evaluated and the summary ROC (SROC) curve was calculated.

RESULTS

Seven out of 46 studies fulfilled the inclusion criteria and were analyzed. Three studies evaluated the use of 18F-FDG PET in the differential diagnosis of renal masses. Two studies analyzed restaging and two analyzed the role of 18F-FDG PET in the detection of metastatic disease. All the selected studies were classified according to Flynn's criteria. We found the highest S in restaging with S 0.87 (95 % CI, 0.75-0.95) and in metastases detection with S 0.72 (95 % CI, 0.56-0.85) as well as the high Sp in differential diagnosis of renal masses.

CONCLUSIONS

The results of this meta-analysis suggest that 18F-FDG PET can be useful in restaging and detection of metastatic disease, based on its acceptable S and Sp. However, the performance of 18F-FDG PET in the detection of primary disease is limited, but this may improve with the new PET/CT systems.

Recurrencia de un carcinoma gástrico de células en anillo de sello demostrada por PET-FDG

OBJECTIVE

To present the case report of a patient with undifferentiated and diffuse signet-ring cell gastric carcinoma in which FDG-PET evidenced recurrent disease.

MATERIALS AND METHODS

The patient was diagnosed of a stage III gastric carcinoma in 1994 and was treated with a subtotal gastrectomy. In February 2003, recurrent disease was detected in mediastinal and left supraclavicular lymph nodes. The patient was treated with chemotherapy and radiotherapy, reaching a complete response. After 6 months free of disease, he presented an elevation of the tumor markers with negative results in conventional imaging methods (upper digestive endoscopy, bone scintigraphy, and CT). An FDG-PET scan was performed to rule out recurrent disease.

RESULTS

FDG-PET detected pathologic findings suggestive of malignant disease in right supraclavicular and mediastinal lymph nodes. These findings were confirmed by clinical follow-up and with another CT scan performed 4 months later.

CONCLUSIONS

In this case report we stress the importance of early recurrence by FDG-PET in a non-intestinal gastric carcinoma. This is of interest given the greater difficulty to detect mucous secreting and/or producing carcinomas with the PET-FDG.

Impacto de la tomografía por emisión de positrones mediante 18-Fluoro-2-Desoxi-D-Glucosa (PET-FDG) en el manejo terapéutico de pacientes con recurrencia secundaria a cáncer de ovario

AIM

Recurrent ovarian cancer is a major problem and an accurate diagnosis can often change patients' management. This study aimed to assess the impact on management of FDG-PET in recurrent ovarian cancer.

MATERIAL AND METHODS

Forty-three patients in whom FDG-PET scan was performed due to suspected recurrent ovarian cancer were included. FDG-PET results were confirmed by histopathology and clinical follow-up of at least 12 months. To assess impact on management the treatment plan based on conventional imaging methods was compared with the treatment plan based on inclusion of PET findings, classifying FDG-PET impact on management as high, medium, low or no impact. Management changes, when present, were classified as intermodality or intramodality.

RESULTS

FDG-PET had a high impact on therapeutic management in 28 patients (65.1 %), medium impact in 2 patients (4.6 %), low impact in 9 patients (20.9 %), and no impact in 4 patients (9.3 %). FDG-PET induced an intermodality change in management in 27 patients (62,8 %); intramodality changes were induced in 3 patients (7 %). Finally, it produced no treatment changes in 13 patients (30.2 %).

CONCLUSION

FDG-PET supplied additional information when compared to conventional diagnostic procedures and allowed adequate management changes in most patients.

Hipercaptación esplénica secundaria a factor estimulador de colonias granulocitarias (G-CSF) en el estudio PET-FDG

We present the case of an 11 year-old Caucasian girl who presented chest pain of 12 weeks evolution, with no other symptoms and a negative physical examination. Lactate dehydrogenase levels were increased to 797 U/l, whereas beta-2-microglobulin (BM2) levels were normal. The thoracic CT showed a bulky mediastinal mass that occupied the pretracheal, paratracheal and right prevascular regions. The gallium scintigraphy showed high uptake in the mediastinic region; the bone scintigraphy was negative. Biopsy of the mediastinal mass revealed the presence of diffuse large B-cell non-Hodgkin's lymphoma. Treatment included 4 cycles of chemotherapy followed by 7 days of subcutaneous granulocyte colony-stimulating factor (G-CSF, Lenogastrim) at a dose of 5 mg/Kg/day. Following treatment, a CT scan was performed to evaluate response, finding a calcification of the mass without significant reduction of the overall size. Because CT was inconclusive in the assessment of response to therapy, a 18F-FDG PET scan was performed. The 18F-FDG PET scan did not show any pathological uptake in the mediastinum but revealed a splenic and bone marrow diffusely increased 18F-FDG uptake. The differential diagnosis included a secondary effect induced by G-CSF therapy as one of the main possibilities, but other possibilities such as a malignant infiltration by lymphoma could not be discarded. Therefore, a second 18F-FDG PET scan was performed 3 months later. This study showed no pathological findings, with a normal 18F-FDG uptake in the spleen and bone marrow. Thus, the benign and reactive nature of the splenic and bone marrow 18F-FDG increased uptake found in the previous study was confirmed. We consider that the stimulating effect that G-CSF therapy has on the spleen and bone marrow must be taken into account when performing a 18F-FDG PET scan, as it can be an important source of false-positive results.

Drug therapy and cerebral perfusion in obsessive-compulsive disorder

Cerebral perfusion in a previously untreated patient with obsessive-compulsive disorder was studied qualitatively and semi-quantitatively with SPECT before, and during and 6 wk after treatment with clomipramine. The patient's symptoms disappeared while on medication and relapsed after drug withdrawal. At baseline, there was an increased perfusion ratio in the bilateral orbitofrontal, anterior cingular, frontotemporal and right caudate regions. These alterations disappeared during drug therapy. After treatment discontinuation and symptomatic relapse, the same pattern of hyperactivity was found. Semiquantitative measurements after treatment withdrawal showed a return to perfusion values similar to those observed before treatment in subcortical structures. In cortical areas, this level was not completely achieved. Subtraction SPECT images showed perfusion changes at the orbitofrontal, caudate and thalamic levels.