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D Blocklet

Publications and source records attributed to D Blocklet.

12 recordsLinked to original sources
PubMed2001

Bone, bone marrow, and MIBI scintigraphic findings in Gaucher's disease "bone crisis".

PURPOSE: The authors report the utility of Tc-99m MIBI imaging in Gaucher's disease, which results in the accumulation of glucocerebroside in macrophages. Inflated macrophages, or Gaucher's cells, involve the reticuloendothelial organs. MATERIALS AND METHODS: A 38-year-old man with type I Gaucher's disease, splenectomy, and early bone involvement was examined for a low back "bone crisis." He had a history of total left hip replacement. Results of pelvic radiographs were normal. Magnetic resonance imaging showed complete infiltration of the bone marrow in the lumbar spine and the sacrum. The left iliac bone, the sacrum, and the adjacent part of L5 showed heterogeneously decreased uptake on bone scintigraphs. Hematopoietic bone marrow was absent in these regions and in the left femur. No infection of the prosthesis was revealed with labeled granulocytes. RESULTS: Avascular necrosis in the left iliac bone was diagnosed, which is a very unusual location. There was no uptake of MIBI in the iliac bones or the femurs. CONCLUSION: These findings suggest that MIBI may not be a good tool for the evaluation of medullary infiltration by Gaucher's cells.

Adult↗
PubMed1999

Maximum-likelihood reconstruction with ordered subsets in bone SPECT.

UNLABELLED: This study was aimed at determining whether the ordered-subset expectation maximum (OSEM) is more effective than filtered backprojection (FBP) for bone SPECT in the routine clinical context. METHODS: Fifty-seven consecutive bone SPECT studies were analyzed. They included pelvic and lumbar spine, thoracolumbar spine, head and neck, feet and shoulders. A 64-projection SPECT study was acquired over 360 degrees by single-head cameras 2-3 h after the injection of 750 MBq 99mTc-methylene diphosphonate. Three observers compared the OSEM and FBP reconstructed images. RESULTS: Streak artifacts, always present with FBP, were rarely generated with the OSEM. When present (n = 24), artifacts associated with negative values near hyperactivities in FBP were not generated with the OSEM in 67% of the cases (n = 16), permitting a satisfactory interpretation of these regions. In half of the other cases (17%, n = 4/24), interpretation was precluded. In only one case did the three observers agree that more hyperactivities were seen with the OSEM. Ninety-six percent of the OSEM pictures were superior or equal to FBP for anatomic resolution and were clearly better in 12% of the cases. The extent of the lesion with the OSEM seemed better or equally defined in 96% and clearly better in 14% of the cases. The low-activity regions were better or equally visualized in all cases and were clearly better seen in 23% of the cases. The quality of the pictures was found to be better or superior with the OSEM in 98% of the cases and definitely better in 65% of the cases. CONCLUSION: Replacement of FBP by the OSEM in bone SPECT would be beneficial to clinical practice.

Artifacts↗
PubMed1999

Sentinel lymph node mapping in the management of high risk malignant melanoma.

In patients with malignant melanoma, the selective biopsy of the first draining lymph node, so-called the sentinel lymph node, allows to identify, with a low morbidity, the patients with nodal metastasis that require radical lymphadenectomy and adjuvant systemic chemotherapy. Herein, we report our initial experience in sentinel lymph node biopsy in 16 patients with malignant melanoma. The sentinel lymph node was localised using preoperative lymphoscintigraphy and injection of dye blue. Intraoperatively, the dissection was guided with a gamma probe and by the recognition of the blue nodes. In the 16 cases the sentinel lymph node was localised. In 50% of the cases, multiple sentinel nodes were demonstrated at lymphoscintigraphy and found during surgery. A limited postoperative morbidity was observed in three cases. Three patients presented nodal metastasis and underwent further radical lymphadenectomy. We conclude that sentinel lymph node mapping is a feasible and reproductive procedure. The preoperative lymphoscintigraphy is essential to identify multiple sentinel nodes and guide surgical dissection. The impact of this approach on the overall survival of patients with high-risk melanoma has still to be demonstrated in studies with a long follow-up.

Adult↗
PubMed1998

99mTc-sesta-(2-methoxy-isobutyl-isonitrile) uptake by pancreatic islets, parotid cells, and mammary carcinoma cells.

99mTc-sesta-(2-methoxy-isobutyl-isonitrile)(Tc-MIBI) is currently used for imaging of several organs. In the present study, its uptake by rat pancreatic islets, rat parotid cells, and human breast adenocarcinoma cells (MCF-7 cells) was found to be grossly proportional to its concentration (up to 0.1 microM), time-related (with a fractional turnover rate close to 2-3 10(-2).min(-1)), and stimulated by D-glucose. Comparable values for the fractional turnover rate were found in prelabeled islets and MCF-7 cells, D-glucose failing to affect Tc-MIBI efflux from prelabeled islets. In the islets, the uptake of Tc-MIBI was decreased at low temperature, in the presence of mitochondrial poisons and at high extracellular K+ concentration, unaffected by the absence of extracellular Ca2+, and increased by nutrient secretagogs, such as 2-ketoisocaproate and the association of L-leucine and L-glutamine. These findings are consistent with the view that Tc-MIBI uptake is ruled by its extracellular concentration, and the polarization of both plasma and mitochondrial membranes. It is proposed that this lipophilic cation may be useful to detect alteration of nutrient metabolism in pancreatic islets deprived of any exogenous fuel.

Animals↗
PubMed1997

Presurgical localization of abnormal parathyroid glands using a single injection of technetium-99m methoxyisobutylisonitrile: comparison of different techniques including factor analysis of dynamic structures.

Single-tracer methoxyisobutylisonitrile (MIBI) imaging is considered to be a sensitive method for the localization of abnormal parathyroid glands. The aims of this study were to determine which of the analytical techniques described for this method - visual comparison of early (15-min) and late (120-min) images, use of time-activity curves (TACs) generated on regions of interest and factor analysis of dynamic structures (FADS) - corresponds best with surgical findings, and to ascertain the potential overall contribution of presurgical scintigraphy. Fifty-five patients were studied, 34 of whom presented with primary hyperparathyroidism (HPT) and 21 with secondary HPT. After a 925 MBq injection of technetium-99m MIBI, a 40-min dynamic acquisition was performed and static images were acquired at 5, 20, 40 and 120 min using a gamma camera equipped with a pinhole collimator. The dynamic series were submitted to FADS, an attractive non-operator-dependent technique, and TACs were generated on regions of interest after the visual comparison of early and 120-minute images (15'-120'). The presumed localizations of abnormal glands were compared with a sketch drawn by the surgeon. Sensitivity was defined as the percentage of true-positive localizations and was 84.4%, 74% and 65% in adenoma and 76%, 66.6% and 45% in hyperplasia for 15'-120', FADS and TACs, respectively. Surgical accuracy, i.e. the percentage of patients accurately and completely described, was 72%, 56% and 59% in adenoma and 53%, 30% and 22% in hyperplasia for 15'-120', FADS and TACs, respectively. The visual comparison method scored best in all cases. FADS was found to be sensitive in cases of adenoma but was handicapped by more false-positive localizations. TACs were particular inefficient in hyperplasia. With respect to the detection of adenomas, we found a relationship between the gland weight and scintigraphic positivity. This dependence on gland weight was not found in hyperplasia. The poorer results obtained with all techniques for surgical accuracy can be explained by the need for a complete scintigraphic description of all pathological glands found by the surgeon in a patient. This study demonstrates that the 15'-120' visual comparison method is more efficient and less cumbersome than TAC or the attractive FADS technique. However, it was less efficient than neck exploration by an experienced surgeon. Therefore, in our institution, scintigraphic studies are now only requested in selected cases of HPT, usually primary HPT and cases undergoing re-operation.

Adenoma↗
PubMed1997

The bone isoenzyme of alkaline phosphatase in hypercalcaemic cancer patients.

Alkaline phosphatase (AP) is the classic marker of bone formation, especially in cancer patients, but the interpretation of its measurement is complicated by the existence of various circulating isoenzymes, especially of liver origin. The introduction of a mass measurement of the bone isoenzyme of AP (BAP) by an immunoradiometric assay has markedly improved the sensitivity and the specificity of the determination. We measured BAP and other markers of bone turnover in 46 patients with tumour-induced hypercalcaemia (TIH), which is an interesting model for evaluating markers of bone formation because of the uncoupling between bone formation and bone resorption found by histomorphometric techniques. The extent of bone metastatic involvement was evaluated by planimetry on bone scintigraphy. Mean (+/- S.D.) BAP concentrations were slightly higher in patients with TIH than in healthy subjects, 15.5 +/- 8.5 versus 12.4 +/- 3.5 micrograms/L (P < 0.05). However, the scatter of the data in TIH patients was quite marked. Increased values (10/46 patients, 22%) occurred only in patients with bone metastases. Total AP, gamma GT and BGP levels, as well as markers of bone resorption, were not significantly different between patients with or without bone metastases. BAP levels were significantly correlated with AP (rs = 0.63; P < 0.01) but not with BGP levels nor with markers of bone resorption. BAP levels were also correlated with the extent of bone uptake at scintigraphy (rs = 0.54; P < 0.01), but this was not the case for total AP or BGP. In the 36 patients re-evaluated when normocalcemic after pamidronate therapy, BAP levels increased from 16.3 +/- 9.2 to 22.2 +/- 21.3 micrograms/L (P < 0.05) but there were no significant changes in AP or BGP concentrations. In summary, our data confirm the existence of an uncoupling in bone turnover in TIH and indicate that cancer hypercalcaemia is another pathological condition characterised by a discordance between BAP and BGP concentrations. BAP levels appear to be a better reflection of bone metastatic involvement than total AP or BGP and their short-term increase after pamidronate therapy could reflect the recently described effects of bisphosphonates on osteoblasts.

Adult↗