RESUMEN

The long-term precision of chromium-51 ethylenediamine tetraacetic acid (51Cr-EDTA) measurements of glomerular filtration rate (GFR) was evaluated in a retrospective study of data obtained over a 12 year period. Each GFR measurement was derived from plasma samples taken at 2, 3 and 4 h following injection of 3 MBq 51Cr-EDTA. The records of 7507 patients were reviewed, from which 55 subjects were identified as having had studies on 10 or more occasions. The mean number of studies per patient was 12.9 (range 10-23) over a mean period of 9.4 years (range 4.3-11.8 years). Plots of GFR, clearance half-life, (T1/2) and volume of distribution (VD) were drawn for each patient and used to identify subjects showing linear changes with time that could be fitted using linear regression. Each residual was expressed as a percentage of the expected value calculated from the regression line and all the residuals combined to give histograms for GFR, T1/2 and VD. Each histogram was fitted with a normal distribution between the -3 S.D. and +3 S.D. limits using weighted least squares. Final results for the coefficient of variation were: GFR 9.8%, T1/2 6.7%, VD 9.4%. The precision errors were used to calculate the smallest statistically significant change measurable by the 51Cr-EDTA technique. With 10% significance and 80% power, the smallest measureable change was 30% for GFR and 20% for T1/2. Unless there are clinical grounds for thinking that a patient's volume of distribution has changed, T1/2 is the optimal parameter for identifying real changes in renal function.

Asunto(s)

RESUMEN

The preparative conditions for 186Re(V)DMSA and 188Re(V)DMSA (DMSA = meso-dimercaptosuccinic acid), beta-emitting radiopharmaceuticals that have been shown to localize in medullary thyroid carcinoma, require modification depending on the amount of carrier rhenium and the chemical form and medium in which the rhenium is supplied. Preparative conditions are described for use with carrier-free 188ReO4- in saline, and for use with 186ReO4- in saline, sodium hydroxide or nitric acid. Preparation of 186Re(V)DMSA (carrier present up to 2 mg per 2.5 ml reaction volume) requires a DMSA:SnCl2:Re ratio of 10:5:1 at 100 degrees C for 30 min. Addition of excess nitric acid or hydrochloric acid up to a concentration of 155 mM does not reduce the yield from 100%. A commercial DMSA kit vial (e.g. Amerscan DMSA) can be used for preparation of 188Re(V)DMSA (carrier free) provided the required activity is in a volume of less than 1 ml per vial. A convenient method of concentrating the 188Re generator eluate to the required volume is described.

Asunto(s)

RESUMEN

Technetium-99m (99Tcm) (V) dimercaptosuccinic acid (DMSA) is a new tumour imaging agent that has been used to image squamous cell carcinoma (SCC) of the head and neck. This study has been undertaken to compare clinical examination with computed tomography (CT) (anatomical) and SPECT 99Tcm (V) DMSA (physiological) imaging in the evaluation of metastatic SCC of the neck. Twenty-five patients with head and neck cancer were studied. Computed tomography was as sensitive but more accurate than clinical examination in predicting the presence of cancer. SPECT 99Tcm (V) DMSA was inferior to both techniques in identifying metastatic disease. There is no role for SPECT 99Tcm (V) DMSA imaging in the management of patients with SCC metastatic to the neck. Combined imaging with CT offered no advantages over anatomical imaging with CT alone. There is no role for CT in the routine evaluation of the clinically N0 neck and the role of CT of the neck in the management of patients with metastatic SCC is discussed.

Asunto(s)

RESUMEN

This study used an established rabbit tumor model with squamous carcinoma to evaluate the pharmacokinetics and biodistribution of technetium-99m-(V)dimercaptosuccinic acid. A total of 54 rabbits were studied (25 with no tumor; 29 with tumor). Technetium-99m(V)dimercaptosuccinic acid had a bi-exponential blood clearance in rabbits with no tumors (28 and 325 min) and in rabbits with tumors (27 and 352 min). There was no significant difference (p greater than 0.05) in mean clearance times between the two groups and clearance appeared unaffected by tumor mass. Technetium-99m(V)dimercaptosuccinic acid had a bi-exponential cumulative urine excretion with no apparent difference in half-times between non-tumor and tumor rabbit groups (200 and 240 min, respectively). Technetium-99m(V)dimercaptosuccinic acid had a major organ biodistribution in rabbits which included bone, kidneys, bladder and the blood pool. The major route of excretion was via the urine. There was no significant difference (p greater than 0.05) in organ biodistribution between rabbits with no tumors and rabbits with tumors and there was no evidence of active uptake of technetium-99m(V)dimercaptosuccinic acid by either squamous carcinoma or inflammatory tissue.

Asunto(s)

RESUMEN

Technetium-99m (99mTc) (v) dimercaptosuccinic acid (DMSA) is a new tumour-imaging agent which has been used to image head and neck squamous carcinoma. This study used an established rabbit tumour model to compare palpation versus planar scintigraphy in the detection of superficially transplanted cancers. Palpation detected 83% of tumours measuring less than 2 cm compared with 58% for scintigraphy. Overall, the sensitivity for palpation was 88% (77% specificity) compared with 50% (63% specificity) for scintigraphy.

Asunto(s)

RESUMEN

Technetium-99m (Tc99m)(v) Dimercaptosuccinic Acid (DMSA) is an imaging agent which has been proposed as a scintigraphic marker for head and neck squamous cell carcinoma. Fifty-four patients were studied of whom 51 had a head and neck tumour. All patients were examined and then imaged using Tc99m(v) DMSA scintigraphy and computerized tomography. Scintigraphy was less sensitive than clinical examination in the detection of patients with cancer, patients with primary tumours and patients with metastatic neck disease. CT was as sensitive and as accurate as clinical examination but more sensitive than Tc99m(v) DMSA in detecting patients with cancer and with primary tumours. CT was more sensitive and more accurate than both clinical examination and Tc99m(v) DMSA scintigraphy in predicting which patients had metastatic neck disease. Although Tc99m(v) DMSA is accumulated by squamous cell carcinoma, its inability to detect low volume disease and apparent low specificity means it has no role to play in the management of patients with head and neck squamous cell carcinoma.

Asunto(s)

RESUMEN

Technetium-99m(99Tcm) (V) dimercaptosuccinic acid is a new imaging agent which has been used to evaluate head and neck squamous cell carcinoma (SCC). This study compared the subcellular biodistribution of 99Tcm(V)DMSA in an established rabbit tumour SCC model and in humans with head and neck SCC. In rabbits, approximately 17-37% of radioactivity was located on tumour cell membrane. Approximately 57-80% of radioactivity was located nonspecifically in tumour cytosol, only 2-6% was bound specifically to tumour mitochondria, and 1-4% bound specifically to microsomes. In humans, 25-45% of radioactivity was localized on tumour cell membrane and 28-60% localized nonspecifically in tumour cytosol. There was 11-20% of radioactivity specifically bound inside the cell to the mitochondria and 1-6% specifically bound to microsomes. These results show that although 99Tcm(V)DMSA is accumulated at sites of SCC, the localization process is nonspecific.

Asunto(s)

RESUMEN

Technetium-99m (99Tcm)(V) dimercaptosuccinic acid (DMSA) is a new tumour imaging agent which has been used to evaluate squamous carcinoma (SCC) of the head and neck. This study evaluated the pharmacokinetics and biodistribution of 99Tcm(V)DMSA in patients with SCC and calculated the bone mass of a New Zealand White (NZW) rabbit. This data was then used to calculate the effective dose equivalent in man. A total of 16 patients were studied (5 with no tumour, 11 with tumour). 99Tcm(V)DMSA had a fast bi-exponential blood clearance in patients with no tumour (30 and 401 min) and patients with tumour (30 and 387 min) with no significant difference (p greater than 0.05) between the two groups. 99Tcm(V)DMSA had a fast cumulative urine excretion with mean half-times in non-tumour and tumour patients of 183 min and 244 min respectively. There was no significant difference (p greater than 0.05) between these two latter groups. The effective dose equivalent of 99Tcm(V)DMSA in man is 5.1 microSv/MBq.

Asunto(s)

RESUMEN

Technetium-99m (99Tcm) (v) dimercaptosuccinic acid (DMSA) is a new tumour imaging agent which has been used to evaluate head and neck tumours. It has a normal head and neck biodistribution to include the lacrimal glands, nasal mucosa and the blood-pool. Seventy-seven patients were studied of whom 63 had a head and neck malignancy. Of these patients, 19 (25%) exhibited positive accumulation of radioactivity in the region of the pituitary gland and this was a constant finding in those followed-up after treatment. Biodistribution studies in forty New Zealand white rabbits confirmed pituitary accumulation of 99Tcm (v) DMSA. The pituitary gland region should be included in the normal biodistribution of 99Tcm (v) DMSA.

Asunto(s)

RESUMEN

Technetium-99m (99Tcm) (v) dimercaptosuccinic acid (DMSA) is a new tumour imaging agent which has been used to image medullary carcinoma of the thyroid and squamous cell carcinoma (SCC) of the head and neck. This study was undertaken to compare planar scintigraphy in patients with head and neck SCC using 99Tcm (v) DMSA and the established tumour imaging agent gallium-67 citrate (67Ga). Seventeen patients were studied of whom 16 had a head and neck malignancy. Clinical examination was more sensitive and accurate than 67Ga scintigraphy, which in turn was more sensitive and accurate than 99Tcm (v) DMSA in detecting patients with cancer, patients with primary tumours and patients with metastatic neck carcinoma. Neither 67Ga or 99Tcm (v) DMSA planar scintigraphy has any role to play in the routine evaluation at presentation of patients with head and neck SCC.

Asunto(s)

RESUMEN

Technetium-99m (99Tcm) (v) dimercaptosuccinic acid (DMSA) is a new tumour imaging agent which has been used to image squamous cell carcinoma (SCC) of the head and neck. This study was undertaken to compare planar versus SPECT 99Tcm (v) DMSA scintigraphy in patients with head and neck SCC. Thirty-four patients were studied. Twenty-eight had SCC, and of these, four had received previous treatment with surgery or irradiation. SPECT was as sensitive and as accurate as clinical examination (but more sensitive and accurate than planar scintigraphy) in detecting which patients had cancer and which patients had primary tumours. SPECT was more sensitive and more accurate than planar scintigraphy (but less sensitive and accurate than clinical examination) in detecting lateral neck compartments with metastatic carcinoma. SPECT correctly upstaged 6% of clinically N0 necks. Although SPECT 99Tcm (v) DMSA scintigraphy improved the image quality, sensitivity and spatial resolution of the investigation, it has no role to play in the routine evaluation of patients with head and neck SCC (to include the clinically N0 neck).

Asunto(s)

RESUMEN

99Tcm(v)-DMSA is a new tumour-imaging agent which has recently been proposed as a scintigraphic marker for head and neck squamous cell carcinoma (SCC). Seventy-seven patients were studied prospectively, of whom 58 had a history and diagnosis of head and neck SCC. All patients were examined, imaged using 99Tcm(v)-DMSA planar scintigraphy and then followed up clinically. In addition, 35 patients were followed up with scintigraphy (81 studies). Scintigraphy was less sensitive and less accurate than clinical examination for the overall detection of patients with SCC, for the detection of patients with SCC at presentation and for the detection of patients with primary tumours, possible nodal disease and with residual and recurrent disease following surgery and irradiation. Approximately 50% of patients exhibited positive uptake of 99Tcm(v)-DMSA in the salivary glands following radiotherapy. Although 99Tcm(v)-DMSA is accumulated at sites of head and neck SCC, its inability to detect low volume disease and apparent low specificity following surgery and irradiation means it has no role to play in the routine evaluation of patients with head and neck SCC.

Asunto(s)

RESUMEN

99Tcm-(V)-DMSA is a new tumour imaging agent which has been used to image squamous cell carcinoma (SCC) of the head and neck. There have been, however, no studies to date evaluating its optimal imaging time for SCC. Seven patients were studied (six SCC; one nontumour) and seven rabbits (six with SCC, (17 tumours); one nontumour). For the human qualitative studies there was a 67% sensitivity at 2, 4 and 6 h with image quality being optimum at 4 h. Maximum quantitative uptake occurred between 2 and 4 h. For the rabbit qualitative studies the optimum imaging time was 4 h (92% sensitivity, 100% specificity) and maximum quantitative uptake occurred at between 1.5 and 5 h. Taking into account the human and rabbit qualitative and quantitative studies combined with the pharmacokinetics and biodistribution of 99Tcm-(V)-DMSA, the optimum imaging time of 99Tcm-(V)-DMSA in humans with SCC was between 2 and 4 h.

Asunto(s)

RESUMEN

A recently developed imaging agent, technetium-99m (v) dimercaptosuccinic acid (99mTc (v) DMSA), has been used to assess head and neck squamous carcinoma (SCC). We have prospectively studied 62 patients of whom 53 had a histologically proven head and neck SCC. The remaining nine had benign lesions. The results of planar imaging in patients with primary disease yielded an 85% sensitivity and 78% specificity. Planar imaging in patients with cervical lymphadenopathy revealed a 59% sensitivity. Nineteen patients also had single photon emission computed tomography imaging which improved the image quality, spatial resolution and sensitivity of the investigation. Twenty-seven patients were scanned before and after radiotherapy and, of these, 96% showed positive uptake in the salivary glands with no evidence of tumor recurrence. This study has shown 99mTc (v) DMSA imaging provides a cheap and rapid method of investigating head and neck SCC and further studies are necessary to evaluate its role in the management of patients with this disease.

Asunto(s)

RESUMEN

Nine patients with histologically proven medullary carcinoma of the thyroid (MCT) were imaged using pentavalent [99mTc]dimercaptosuccinic acid [(V)DMSA], [131I] metaiodobenzylguanidine (MIBG) and [99mTc]methylene diphosphonate (MDP). Technetium-99m (V)DMSA demonstrated most of the tumor sites in eight patients with proven metastases, with an overall sensitivity of 95% in lesion detection. Iodine-131 MIBG showed definite uptake in some of the tumor sites in three of the nine patients imaged, with equivocal uptake seen in a further one patient, with sensitivity of only 11% for lesion detection. Technetium-99m MDP demonstrated bony metastases only, in four of the patients imaged yielding a sensitivity of 61%. Technetium-99m (V)DMSA has been demonstrated in this study to be a useful imaging agent in patients with MCT, showing uptake in significantly more lesions and with better imaging qualities than [131I]MIBG, and with the ability to detect soft tissue as well as bony metastases.

Asunto(s)

RESUMEN

We report our experience using [131I]metaiodobenzylguanidine (MIBG) to image nine patients with proven medullary carcinoma of the thyroid (MCT). Positive uptake was seen in four patients, equivocal uptake in one patient, and no uptake in four patients. Data is presented to demonstrate the pharmacokinetics of [131I]MIBG in three of the patients studied. Two patients, with diarrhea and severe pain from known bone metastases and positive uptake on [131I]MIBG diagnostic scanning, subsequently received therapeutic doses of [131I]MIBG, with marked improvement in both pain and diarrhea, but no evidence of significant biochemical response. Iodine-131 MIBG uptake in patients with MCT is variable, and gives a higher false-negative rate than is found when using [131I]MIBG to image other neuroectodermally derived tumors. The therapeutic potential of [131I]MIBG in patients with MCT warrants further evaluation, in view of the symptomatic relief experienced following therapy doses in two patients with extensive disease.

Asunto(s)

Asunto(s)

RESUMEN

A monoclonal antibody to human thyroglobulin was radiolabelled with 123I NaI and shown to be a stable and biologically active reagent in vivo. When injected intravenously into 12 patients with cancer of the thyroid on thyroxine-replacement therapy, 6 of the 12 patients had localization of the labelled antibody in tumour sites. These results were compared to 131I scans done on the same patients 1 month after stopping thyroxine. The biological half-life of the antibody in the blood was influenced by the levels of circulating thyroglobulin.

Asunto(s)

RESUMEN

A method is described for the quantitation of total skeletal activity during bone scans. The method requires a single plasma sample only, taken at the time of imaging. The ratio of % injected dose of 51Cr EDTA to that of 99Tcm MDP is calculated from this sample following combined injection of the two radiopharmaceuticals. The 51Cr EDTA level corrects for the glomerular filtration of 99Tcm MDP. Using this method, which only requires a gamma counter, significant differences from normal controls have been shown in patients with osteomalacia, renal osteodystrophy, Paget's disease and hypercalcaemia. The method provides routine quantitative data to add to the imaging information in the bone scan.

Asunto(s)

RESUMEN

When a tissue removal rinse technique was compared to the moist-swab contact method, significantly greater numbers of bacteria were recovered from beef carcasses, especially when the flora exceeded log10 4.5/6.45 cm2. Secondary treatment of the removed surface tissue by blending resulted in a significantly greater number of bacteria being recovered than when the same sample was swabbed and/or rinsed. Data indicate that blending of the carcass surface tissue provides a more representative value of the true microbial flora.

Asunto(s)