Ospedale GeneraleRegionaleS.M. dei Battuti, Treviso Istituto di Radioterapia e MedicinaNudeare (Direttore: Prof. P. PATI~ESE)

2°1T1FOR THE DIFFERENTIAL DIAGNOSIS OF COLD THYROID NODULES FRANCO PALERMO ALBERTOCADEL GIANFRANCOBORDIGNON FEDERICO BRUNIERA LIvlO CALDATO MAURIZIODELLA SIEGA MARIO LAZZARINI ANTONIOMARESO

The scintigraphic recognition of the areas of the thyroid tissue with reduced uptake raises a problem of diagnosis and decision, well known to physicians and which has to be confronted almost daily. Therefore there is a need to carry out additional investigations, firstly with radioisotopes and particularly those specifically indicating neoplasms, both because of the lack of any delay in obtaining the information with these methods and because of its value. Up to the present, among the several radiopharmaceuticals proposed for the preoperative study of cold thyroid nodules, 131Cs3,5 is the best known and has given the most discriminating results; in the examination of thyroid nodules its concentration can be considered at least indicative of increased ce.ll proliferation 1,2. Because of the slmilarities of its metabolism with that of potassium and UlCs, we were induced to test the possible use of 2°XT1for differential diagnosis. On account of the favourable physical and ceUular kinetic characteristics of 2°'TI (fig. 1) we have employed it successfully for some time now in the non-invasive radioisotopic examination of the myocardium 4. Thallium, like 'SICs, is normally concentrated in the thyroid parenchyma (fig. 2) less intensely than in the heart; it does not persist indefinitely, and its activity decreases more or less in parallel with that in the myocardium. A further interesting stimulus for this research was given by the recent scintigraphic representations obtained with this radioisotope z s,9 of melanomas and lung tumours. Key-words: Cold thyroid nodules; Neoplasms; Radiopharmaceuticals; Scintigraphy; Z°lTI-chloride. Acceptedfor publication on June 1, 1977. La RicercaClin. Lab. 7, 289, 1977.

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DIFFERENTIAL DIAGNOSIS OF COLD T H Y R O I D N O D U L E S

MATERIALS AND METHOD So far (December 1976), we have examined 16 patients with thyroid nodules, which had appeared to be 'cold' in a previous scintigram with ~31I-or 9~Tc-pertechnetate; ai1 were re-examined 20-60 rain after administering 1 to 1.2 mCi i.v. of 2"~Tt-chloride (Philips-Duphar, Petten, The Netherlands). In some cases, we simultaneously carried out investigations with double tracing and dualanalyzer digitalized scinfiscans with radioiodine or radiotechnetium as well as radiothallium. Three patients were also studied with other turnout-localizing agents (U~Cs or 67Ga). All the thyroid nodules were removed surgically and examined histologically. Tab. 1 shows the results obtained.

RESULTS I n all five tumours subsequently found to be malignant, the 2°IT1 showed an obvious high concentration: there were three papillary, one follicular (figs 3 and 4) and one anaplastic (fig. 5) carcinoma. A m o n g the nodules histologically diagnosed as benign, only one false positive was found: an high uptake in a microfollicular adenoma (fig. 6); in this case, the test previously carried out with 13~Cs was also positive. As regards the two cases of thyroiditis that we investigated, the 2°1T1 did not show any intranodular accumulation; this differed from the picture with ~3~Cs which was concentrated in an appreciable quantity in the suspect area in one case of subacute thyroiditis. I n the remaining nine benign nodules, the scintigraphic picture with 2°~T1 was practically the same as that of the previous scans with m I or ~mTc (fig. 7).

DISCUSSION O n the basis of this firstsurvey of ours, w e obviously cannot come to any conclusions about the efficacy and sensitivity of the use of thallium for differential diagnosis; the technical and procedural aspects of the investigation are themselves, in our opinion, subject to further improvements; there is also the possibility of utilizing the scintillation-camera connected 'on-line' with a computer, as has been shown with mCs and 67Ga a,4

radiothallium uptake present malignant neoplasms

5

5

~enign neoplasms

9

1"

~yroiditis

2

doubtful -

290

-

-

--

8

--

2

* false positive = 6.25%; false negative = 0; agreement = 93.75%. Tab. 1 - 2°lTl-chloride: differential diagnosis of cold thyroid nodules,

-

absent

decay

CE

X

69-83 (g8~J,/o) key

radiation

"r

half-life

73 hrs

irradiation of patients (rads/mCi)

whole body gonads heart bone marrow kidneys

preferential heart tropism kidneys ( ° dose/g tissue) liver skeletal muscle

135 (2°'o) 167 (8°%)

0,07 0.25 0.32 0,50 6 52

4.30 5.60 1.gO 1.30

Fig. 1 - Physical and biological behaviour of '°'T1. On the right: the window widths selected on the photopeaks of X- and y-ray energy.

Fig. 2 - 2°lTl-chtoride concentration in the normal thyroid parenchyma: scintiphotographic images: with a multi-hole collimator (left); with a pin-hole coltimator (right). 291

Fig. 3 - 2°~Tl-chloride concentration in papillary of right lobe (top) and follicular of left lobe (bottom) adenocarcinomas. 292

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il

~

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Fig. 6 - False positive. A high uptake in a mierofollicular adenoma: on surgicat removal we found a parenchyma alternating with haemorrhagic cystic areas, surrounded by an inflammatory capsule. A ~3~Csscanning showed an analogous hot area in the left lobe.

2ol

TI

99mTc

Fig. 7 - Thyroid adenoma: no accumulation of 2°'T1 in a benign 'cold' area.

294

F. PALERMO

et

al.

In addition to the effective differentiation of benignity or malignity, the scintigraphic representation of thyroid nodules with radiothallium also seems to provide a satisfactory topographical and morphological definition of the relationship of activity between the nodule and the undamaged parenchyma.

SUMMARY We used ~°'Tl-chloride for studying and differentiating thyroid areas shown to be 'cold' in previous :31I or S~=Tc scanning. We investigated sixteen thyroid neoplasms that were removed surgically shortly afterwards. We found an intense intranodular accumulation of 2°'T1 in five scintigraphs shown to be of histologically malignant neoplasms, and an intense accumulation also " not detect any 201Tl-chloride accumulation in one of those shown to be histologically ben i gn. We did in two cases of thyroiditis; one of these had shown an intense accumulation in a previous '3'Cs scintigram.

REFERENCES 1 ) BESTAGNOM., t~EMBADOR., GUERRAV.: Cesium'3' as Scanning Agent in the Evaluation of Cold Thyroid Nodules - J. nucl. biol. Med. 17, 111, 1973. 2) BURAGGIG. L., DI PIETR0 S., DOCI R., RODARIA.: L'esame clinico e io studio con radiocesio (13'Cs) helle diagnosi di natura dei noduli freddi tiroidei - Tumori 62, 397, 1976. 3) CHARK~S N.D., SKLAROVFD.M., GERSHoN-COHEN J., CANTOR R.E.: Tumor Scanning with Radioactive Cesium - J. nucl. Med. 6, 300, 1965. 4) ERJAVECN., AUERSPERGM., GOLOUHR., SNAJDERJ., TURNSEKr.: Computer-Assisted Scanning in Evaluation of *TGa-Citrate Uptake i,a Thyroid Disease - J. nucI. Med. 15, 810, 1974. 5) MURRAYJ., STEWARTR., INDYKJ.: Thyroid Scanning with l~'Cs - Brit. reed. J. iv, 653, 1970. 6) PALERMO F., CA.DEL A., PATRESE P.: Miocardioscintigrafia con radiotallio (~°'Tl-clomro) - La Ricerca Clin. Lab. 6 (Suppl. 1), 38, 1976. 7) POTTS A.M., Au P.C.: Thallous Ion and the Eye - Invest. Ophthal. I0, 925, 1971. 8) SALVATOREM., CARRA~ L., MALPIERI F., BAZZlCALOPOL., MUTO P.: Prime esperienze sulla possibilit~ di impiego del Tallio 201-cloruro come indicatore positivo - In: Atti XV Congr. Naz. SIBMN, Torino, 1975; p. 59. 9) SULMANCH., CAPPELLAE~EP.: The Advantage of Thallium 201 in the Detection of the Malignant Melanoma: Preliminary Results - Europ. J. nucl. Med. I, 103, 1976.

Requests ]or reprints should be addressed to: FRANCOPALERMO Ospedale Generale Regionale S.M. dei Battuti Istituto di Radioterapia e Medicina Nucleare 31100 Treviso - Italia

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