185
Technical notes autoclaved at 120°C ( 15 psi). The final volumes were taken in sterile, disposable, graduated syringes. The following reagents were used in the preparation of 99 mTc-sulfur colloid. (a) Reaction solution: a mixture of 2 ml of 5% mannitol solution together with 0·3 ml of l% sodium thiosulfate solution (1·4 mg of S). (b) Acid: 0·5 ml of l N Hydrochloric acid; (c) Buffer: 1 ml of l M sodium citrate solution. Preparation of the colloid. A sterile solution of 99 mTc0 - (l-5 ml) in normal saline was added to the 4 reaction solution and then 0·5 ml of acid was asceptically transferred into it, followed by heating the vial in a boiling water bath for 5 min. It was then cooled in air for a minute and under running tap water for 2 min and finally the buffer was asceptically added to it, and the contents were well mixed. The final pH was 6·2-6·5; and the product was ready for use in humans. This radiopharmaceutical has been used clinically within 6 hr after the preparation.
Results Biological criteria. Since the commonly employed procedures in paper chromatography using 85: 15 methanol-water solvent do not serve as a good index for critical evaluation of the radiopharmaceutical, biological distribution in mice (Swiss-strain) was adopted for purposes of quality control. Invariably the percentage uptake of the injected dose in the liver at the time of sacrifice (15 min) was 90 ± 3·0, and in the spleen 2·5 ± 0·5. Very little activity was retained in the lungs, thyroid, stomach-intestines and the kidneys. The blood background was negligible, thus showing the abscence of any unlabelled free 99 mTc04and the efficiency of the labelling process. Effect of autoclaving. Tissue distribution studies in mice have indicated that even if the slightly opalescent 99 mTc sulfur colloid was autoclaved at l20°C at 15 psi TABLE l. Organ distribution of 99 mTc-sulfur colloid in mice % Administered dose 99 mTc-S colloid colloid (Autoclaved) product) (Normal 99 "'Tc-S
Liver Spleen Lungs Stomach)
inte~ines Kidneys Blood
90·0 ± 3·0 2·6 ± 0·5 0·4 ± 0·2
85 ± 5·0 2·3 ± 0·3 0·4 ± 0·2
0·4 ± 0·1
1·5 ± 0·3
0·1 ± 0·1 0·25 ± 0·15
0·2 ± 0·1 0-4 ± 0·1
for 20 min, when it turned into a clear solution, the concentration in the liver and spleen were not markedly changed as shown in Table I. Little activity was seen in the stomach and intestines. The pH value and the paper chromatographic patterns (R1 = 0) were not altered. 0. P. D. NoRONHA Radiation Medicine Centre Bhabha Atomic Research Centre A. B. SEWATKAR R. D. GANATRA Tata Memorial Hospital H. J. GLENN* Parel, Bombay-400 012 India
References 1. HARPER P. V., LATHROP K. A. and RICHARDS P. J. nucl. Med. 5, 382 (1964). 2. HARPER P. v., LATHROP K. A., JIMINEZ F., FINK R. and GoTTSCHALK A. Radiology 85, 10 l (1965). 3. PATTON D. D., GARciA E. N. and WEBER M. M. Am. J. Roentgenol. Radiat. ther. nucl. Med. 91, 880 ( 1966). 4. STERN H. S., McAFEE J. G. and SuBRAMANIAN G. J. nucl. Med. 7, 665 (1966). 5. LARSON S. M. and NELP W. B. J. nucl. Med. 7, 817 (1966). 6. SzYMENDERA J., ZoLTOWSKI T., RADWAN M. and KAMINSKAj. J. nucl. Med.12,212 (1971). 7. HuNTERjR. W. W. J. nucl. Med. 10,607 (1969). 8. STAUM M. M. J. nucl. Med. 13, 386 (1972). 9. HALL J. N., O'MARA R. E. and TYSON I. J. nucl. Med. 13, 868 (1972). 10. BoYD R. E. Radiopharmaceuticals from Generator Produced Radionuclides-Panel Proceeding Series p. 56. IAEA, Vienna (1971). 11. CIFKA J. and V ESE LEY P. Radiopharmaceuticals and Labelled Compounds-Proceedings of a Symposium, Vol. 1, p. 53. IAEA, Vienna (1973). 12. BRUUN P. J. nucl. Med. 15, 726 (1974). 13. SEwATKAR A. B., NoRONHA 0. P. D., GANATRA R. D. and GLENN H. J. Nuclear-Medi;:,in 14, 46 (1975). International Journal of Nuclear Medicine and Biology, 1975, Vol. 2, pp. 185-188. Pergamon Press, Printed in Northern Ireland
Estitnation of Thyroid Weight by Scintigraphy
(Received 13 June 1974; in revisedform 23 December 1974)
Numberofanimals: 20. Timeofsacrifice: 15 min.
The majority of authors agree that thyroid weight must be taken into account when estimating the * W.H.O. visiting scientist.
Technical notes
186
TABLE 1 I II
M = or.v' A3 + {J M=a.AW+fl
XI XII
M = (JA« M = {J(AW)«
III M = a.Av'HW + {J XIII M = {J(A v' HW)a. XIV M = {J[A(D 1 + D 2 W IV M = or.S(D1 + D 2 ) + {J v M = a.D1D 2 + {J XV M = {J(D 1D 2 )a. VI M=a.HW 2 +{J XVI M = {J(HW2)« VII M=a.AH+{J XVII M = {J(AH)« XVIII M = (JH« VIII M=or.H+{J IX M=a.W+{J XIX M = {JWa. X M = or.(D1 + D 2) + fJ M =weight; W =width; A =area; D 1, D 2 =diagonals; H =height therapeutic dose of 131I for treatment of hyperthyroidism. The methods proposed nowadays are palpation, pneumogram< 3> and scintigraphy< 4- 9>. The first one is subjective and inaccurate whereas the second is cumbersome. It is astonishing that the scintigraphic method didn't elicit a greater response since it gives more reproducible and accurate results. The work reported in this paper consists in assessing the accuracy of the formulae proposed< 4 •9 > on a larger number of experimental cases and establishing an abacus for practical use. The validity of the formula for the determination of total thyroid volume, as well as for thyroid lobe was tested. Finally, the influence of scanning conditions (velocity, tap factor, background subtraction) on the measurements were tested on a thyroid phantom. Materials and Method The study was performed on 75 thyroid glands, of these 46 patients had undergone total or subtotal thyroidectomy and 29 patients had undergone lobectomy. Fifty-six of them had non toxic multinodular goiter, 10 diffuse toxic goiter, 5 toxic multinodular or nodular goiter, 3 cases of Hashimoto's thyroiditis, and 1 case of thyroid cancer. The weight ofthe operative material was measured and corrected according to the surgeon's estimate of the residual thyroid tissue. This correction never exceeded 5 g. The weights found ranged from 12 to 400 g. Preoperative frontal thyroid scintigrams were made by a routine technique in our laboratory without background subtraction on a Philips*
* 3 x 2 in. crystal. Fine focus collimator 69 channels focal plane at 26 mm used for 131!.
and on a PHO-DOTt scanner, after administration of 50 ftC 131I or 1 mCi 99mTc. The following measurements were taken from the scintigrams: the height and width of the thyroid Jobes, the length of the two diagonals, and the surface area of the scan which was determined by means of a planimetert. A least square fit of the formulae reported in the table below was done on a CDC 6400 computer. Results and Discussion Like MYHILL et al. (5) we found similar scatter for each of the formulae tested, with the exception of those in which height, width or the sum of the diagonals appear separately, in which cases the scatter is significantly greater. Like SPENCER< 9> we find that the formulae using logarithms are more convenient to handle. The relevant standard deviation and the mean error on the estimate are generally lower. An analysis of covariance was performed on results obtained with formulae XI-XII-XIII-XVIXVII to check whether those formulae might be applied to the determination of thyroid lobe. It was proved that only formulae XII and XVI would not meet the requirements. Our choice went to the relation M = 0·86 x A1·2 6 (M =weight in g, A =area in cm2) (Fig. I) because of its reproducibility, ease of application and minimal technical requirements. This formula uses only one variable, the thyroid area, which is t PRO-DOT (Nuclear Chicago) model 1735. 3 in. crystal. Fine focus collimator. 127 channels focal plane at 100 mm used for 131!, 127 channels focal plane at 95 mm used for 99mTc. t Constructed by Saimoraghi, Milano, Italy. X 3
Technical notes
v Thyroidectomy 200
• Lobectomy
100
"'
-"' .
Technical notes autoclaved at 120°C ( 15 psi). The final volumes were taken in sterile, disposable, graduated syringes. The following reagents were used in the preparation of 99 mTc-sulfur colloid. (a) Reaction solution: a mixture of 2 ml of 5% mannitol solution together with 0·3 ml of l% sodium thiosulfate solution (1·4 mg of S). (b) Acid: 0·5 ml of l N Hydrochloric acid; (c) Buffer: 1 ml of l M sodium citrate solution. Preparation of the colloid. A sterile solution of 99 mTc0 - (l-5 ml) in normal saline was added to the 4 reaction solution and then 0·5 ml of acid was asceptically transferred into it, followed by heating the vial in a boiling water bath for 5 min. It was then cooled in air for a minute and under running tap water for 2 min and finally the buffer was asceptically added to it, and the contents were well mixed. The final pH was 6·2-6·5; and the product was ready for use in humans. This radiopharmaceutical has been used clinically within 6 hr after the preparation.
Results Biological criteria. Since the commonly employed procedures in paper chromatography using 85: 15 methanol-water solvent do not serve as a good index for critical evaluation of the radiopharmaceutical, biological distribution in mice (Swiss-strain) was adopted for purposes of quality control. Invariably the percentage uptake of the injected dose in the liver at the time of sacrifice (15 min) was 90 ± 3·0, and in the spleen 2·5 ± 0·5. Very little activity was retained in the lungs, thyroid, stomach-intestines and the kidneys. The blood background was negligible, thus showing the abscence of any unlabelled free 99 mTc04and the efficiency of the labelling process. Effect of autoclaving. Tissue distribution studies in mice have indicated that even if the slightly opalescent 99 mTc sulfur colloid was autoclaved at l20°C at 15 psi TABLE l. Organ distribution of 99 mTc-sulfur colloid in mice % Administered dose 99 mTc-S colloid colloid (Autoclaved) product) (Normal 99 "'Tc-S
Liver Spleen Lungs Stomach)
inte~ines Kidneys Blood
90·0 ± 3·0 2·6 ± 0·5 0·4 ± 0·2
85 ± 5·0 2·3 ± 0·3 0·4 ± 0·2
0·4 ± 0·1
1·5 ± 0·3
0·1 ± 0·1 0·25 ± 0·15
0·2 ± 0·1 0-4 ± 0·1
for 20 min, when it turned into a clear solution, the concentration in the liver and spleen were not markedly changed as shown in Table I. Little activity was seen in the stomach and intestines. The pH value and the paper chromatographic patterns (R1 = 0) were not altered. 0. P. D. NoRONHA Radiation Medicine Centre Bhabha Atomic Research Centre A. B. SEWATKAR R. D. GANATRA Tata Memorial Hospital H. J. GLENN* Parel, Bombay-400 012 India
References 1. HARPER P. V., LATHROP K. A. and RICHARDS P. J. nucl. Med. 5, 382 (1964). 2. HARPER P. v., LATHROP K. A., JIMINEZ F., FINK R. and GoTTSCHALK A. Radiology 85, 10 l (1965). 3. PATTON D. D., GARciA E. N. and WEBER M. M. Am. J. Roentgenol. Radiat. ther. nucl. Med. 91, 880 ( 1966). 4. STERN H. S., McAFEE J. G. and SuBRAMANIAN G. J. nucl. Med. 7, 665 (1966). 5. LARSON S. M. and NELP W. B. J. nucl. Med. 7, 817 (1966). 6. SzYMENDERA J., ZoLTOWSKI T., RADWAN M. and KAMINSKAj. J. nucl. Med.12,212 (1971). 7. HuNTERjR. W. W. J. nucl. Med. 10,607 (1969). 8. STAUM M. M. J. nucl. Med. 13, 386 (1972). 9. HALL J. N., O'MARA R. E. and TYSON I. J. nucl. Med. 13, 868 (1972). 10. BoYD R. E. Radiopharmaceuticals from Generator Produced Radionuclides-Panel Proceeding Series p. 56. IAEA, Vienna (1971). 11. CIFKA J. and V ESE LEY P. Radiopharmaceuticals and Labelled Compounds-Proceedings of a Symposium, Vol. 1, p. 53. IAEA, Vienna (1973). 12. BRUUN P. J. nucl. Med. 15, 726 (1974). 13. SEwATKAR A. B., NoRONHA 0. P. D., GANATRA R. D. and GLENN H. J. Nuclear-Medi;:,in 14, 46 (1975). International Journal of Nuclear Medicine and Biology, 1975, Vol. 2, pp. 185-188. Pergamon Press, Printed in Northern Ireland
Estitnation of Thyroid Weight by Scintigraphy
(Received 13 June 1974; in revisedform 23 December 1974)
Numberofanimals: 20. Timeofsacrifice: 15 min.
The majority of authors agree that thyroid weight must be taken into account when estimating the * W.H.O. visiting scientist.
Technical notes
186
TABLE 1 I II
M = or.v' A3 + {J M=a.AW+fl
XI XII
M = (JA« M = {J(AW)«
III M = a.Av'HW + {J XIII M = {J(A v' HW)a. XIV M = {J[A(D 1 + D 2 W IV M = or.S(D1 + D 2 ) + {J v M = a.D1D 2 + {J XV M = {J(D 1D 2 )a. VI M=a.HW 2 +{J XVI M = {J(HW2)« VII M=a.AH+{J XVII M = {J(AH)« XVIII M = (JH« VIII M=or.H+{J IX M=a.W+{J XIX M = {JWa. X M = or.(D1 + D 2) + fJ M =weight; W =width; A =area; D 1, D 2 =diagonals; H =height therapeutic dose of 131I for treatment of hyperthyroidism. The methods proposed nowadays are palpation, pneumogram< 3> and scintigraphy< 4- 9>. The first one is subjective and inaccurate whereas the second is cumbersome. It is astonishing that the scintigraphic method didn't elicit a greater response since it gives more reproducible and accurate results. The work reported in this paper consists in assessing the accuracy of the formulae proposed< 4 •9 > on a larger number of experimental cases and establishing an abacus for practical use. The validity of the formula for the determination of total thyroid volume, as well as for thyroid lobe was tested. Finally, the influence of scanning conditions (velocity, tap factor, background subtraction) on the measurements were tested on a thyroid phantom. Materials and Method The study was performed on 75 thyroid glands, of these 46 patients had undergone total or subtotal thyroidectomy and 29 patients had undergone lobectomy. Fifty-six of them had non toxic multinodular goiter, 10 diffuse toxic goiter, 5 toxic multinodular or nodular goiter, 3 cases of Hashimoto's thyroiditis, and 1 case of thyroid cancer. The weight ofthe operative material was measured and corrected according to the surgeon's estimate of the residual thyroid tissue. This correction never exceeded 5 g. The weights found ranged from 12 to 400 g. Preoperative frontal thyroid scintigrams were made by a routine technique in our laboratory without background subtraction on a Philips*
* 3 x 2 in. crystal. Fine focus collimator 69 channels focal plane at 26 mm used for 131!.
and on a PHO-DOTt scanner, after administration of 50 ftC 131I or 1 mCi 99mTc. The following measurements were taken from the scintigrams: the height and width of the thyroid Jobes, the length of the two diagonals, and the surface area of the scan which was determined by means of a planimetert. A least square fit of the formulae reported in the table below was done on a CDC 6400 computer. Results and Discussion Like MYHILL et al. (5) we found similar scatter for each of the formulae tested, with the exception of those in which height, width or the sum of the diagonals appear separately, in which cases the scatter is significantly greater. Like SPENCER< 9> we find that the formulae using logarithms are more convenient to handle. The relevant standard deviation and the mean error on the estimate are generally lower. An analysis of covariance was performed on results obtained with formulae XI-XII-XIII-XVIXVII to check whether those formulae might be applied to the determination of thyroid lobe. It was proved that only formulae XII and XVI would not meet the requirements. Our choice went to the relation M = 0·86 x A1·2 6 (M =weight in g, A =area in cm2) (Fig. I) because of its reproducibility, ease of application and minimal technical requirements. This formula uses only one variable, the thyroid area, which is t PRO-DOT (Nuclear Chicago) model 1735. 3 in. crystal. Fine focus collimator. 127 channels focal plane at 100 mm used for 131!, 127 channels focal plane at 95 mm used for 99mTc. t Constructed by Saimoraghi, Milano, Italy. X 3
Technical notes
v Thyroidectomy 200
• Lobectomy
100
"'
-"' .
