Hikmet Bayhan

Clinical experience with Tc-99m MIBI imaging in patients with malignant tumors. Preliminary results and comparison with Tl-201.

Tc-99m MIBI imaging was performed in 34 patients with histopathologically proven malignant tumors. The study was performed in two steps. In the first step, only Tc-99m MIBI imaging was performed (Group 1). In the second step, both Tc-99m MIBI and TI-201 imaging were performed for comparison (Group 2). Seventeen patients were studied in each step. The size of the smallest primary tumor (breast cancer) was 15 × 10 mm, and that of the largest (lung cancer) was 145 × 130 mm. Of the 34 patients, 26 showed Tc-99m MIBI uptake at the tumor site. In Group 1, 12 patients showed Tc-99m MIBI tumor uptake, but no uptake was detected in five patients (squamous cell carcinoma of the esophagus, teratoma of the testis, nonHodgkins lymphoma, and squamous cell carcinoma of the lung). In Group 2, 13 patients showed both Tc-99m MIBI and TI-201 uptake at the tumor site, but one patient with breast cancer showed only Tc-99m MIBI uptake, and three patients showed no Tc-99m MIBI and TI-201 uptake (embryonal cell carcinoma of the testis, hepatocellular carcinoma). The overall sensitivity of Tc-99m MIBI imaging was 76.4%. In Group 2, the sensitivity was 82.3% for Tc-99m MIBI and 76.4% for TI-201. Our preliminary clinical experience suggests that Tc-99m MIBI can be helpful in localizing malignant tumors and that its sensitivity is slightly higher than TI-201.

Comparison of 99mTc(V)-DMSA, 201Tl and 99mTc-MIBI imaging in the follow-up of patients with medullary carcinoma of the thyroid

Radionuclide scanning with tumour-seeking agents such as pentavalent technetium-99m dimercaptosuccinic acid [99mTc(V)-DMSA], thallium-201 and technetium-99m sestamibi (MIBI) has been reported to be useful in the detection of medullary thyroid carcinoma (MTC). We undertook a study in 14 MTC patients to determine the comparative imaging potential of201Tl, MIBI and99mTc(V)-DMSA in the detection of recurrent or metastatic MTC. All patients underwent total thyroidectomy and had persistently elevated serum calcitonin levels after the surgery. Scintigraphic studies were carried out 20 min after the injection of 111 MBq of201Tl or 555 MBq of MIBI and 2 h following the injection of 370 MBq of99mTc(V)-DMSA. All scintigraphic findings were correlated with contemporaneous CT or MRI studies. CT, MRI and bone scans showed 42 (26 bone, 16 soft tissue) metastatic sites in 11 of the 14 patients. In the remaining three patients no lesions were detected during diagnostic evaluation.99mTc(V)-DMSA showed all of the soft tissue metastases but could not show two bone lesions. On the other hand, MIBI imaging was false-negative in 22 (52%) sites and201Tl was false-negative in 34 (80%) sites. Overall, lesion detection sensitivities for99mTc(V)-DMSA, MIBI and201Tl were 95%, 47% and 19% respectively. We conclude that99mTc(V)-DMSA is clearly superior to MIBI and201Tl in the follow-up of MTC patients.

Assessment of tumour necrosis and detection of mediastinal lymph node metastasis in bronchial carcinoma with technetium-99m sestamibi imaging: comparison with CT scan

Thirty-eight patients with four major types of bronchial carcinoma were studied to evaluate technetium-99m sestamibi imaging in the assessment of tumour necrosis and the detection of hilar and mediastinal lymph node metastasis. Quantitative analysis was also performed to ascertain whether tumour uptake values correlate with histological types of bronchial carcinoma. Of the patients, 34 showed tumour uptake on planar imaging (n = 38) and 27 on single-photon emission tomography (SPET) (n = 29), the overall sensitivity in the localisation of primary tumour being 89% with planar imaging and 93% with SPET. Four types of tumour uptake pattern were identified: (1) focal uptake, (2) focal uptake with a central hypoactive focus, (3) ring-like uptake and (4) no uptake (negative uptake). Tumour necrosis was diagnosed in 12 patients based upon histopathology (n = 2) and density measurements and type of contrast enhancement on computed tomography (CT) scan (n = 12). Defective tumour uptake was seen in 11 of these patients on planar images (focal uptake with a central hypoactive focus, n = 7; ring-like uptake, n = 2; and no tumour uptake, n = 2) and in 12 patients on SPET (focal uptake with a central hypoactive focus, n = 7, ring-like uptake, n = 3, and no uptake, n = 2). Hilar and mediastinal lymph node involvement was detected in ten patients on CT scan, nine on planar images and 11 on SPET. A total of 26 metastatic lymph nodes were detected on CT scan; 24 of these were seen on planar, and all 26 on SPET images. SPET disclosed five further lymph nodes with metastasis, all of which were confirmed by histopathological examination of the surgical material (n = 3). The sensitivity in establishing the hilar and mediastinal disease was 90% on planar images, and 100% on SPET slices, but when the number of lymph nodes was taken into account, these values were 62% and 100%, respectively. Also, brain metastases were detected with SPET in three patients. The results of quantitative analysis of tumour uptake did not differentiate between squamous cell carcinoma and adenocarcinoma. We conclude that 99mTc-sestamibi, particularly with SPET imaging, is potentially useful in the follow-up of patients with bronchial carcinoma by differentiating residual or recurrent disease from postradiotherapy necrosis, and is as sensitive as CT scan in the detection of hilar and mediastinal lymph node metastasis.

Evaluation of cerebral vasospasm in patients with subarachnoid hemorrhage using single photon emission computed tomography.

Cerebral vasospasm (CVS) occurs as a result of the breakdown in cerebral autoregulation mechanisms. Because cerebral vasospasm can occur after subrachnoid hemorrhage (SAH), it is important to evaluate borderline perfusion. Evaluation of borderline vascular insufficiency is important to reduce ischemic complications. In this study 25 patients with SAH were investigated by somatosensory evoked potentials (SEP), computed tomography (CT), digital subtraction angiography (DSA) and single photon emission computed tomography (SPECT) in order to predict borderline ischemic areas. Clinical grades were also correlated with these investigations. Thirteen patients had symptomatic vasospasm and 15 patients had angiographic vasospasm. SPECT showed hypoperfusion in 22 out of 25 patients. CT predicted CVS in 8 of these 22 patients. Our study shows that brain perfusion SPECT is a non-traumatic, non-invasive, non-allergic, inexpensive method for the prediction of cerebral vasospasm. We conclude that brain SPECT with Tc-99m HM-PAO is an accessible technique that can demonstrate varying degrees of regional tissue hypoperfusion in patients with delayed ischemic deficits due to CVS following SAH.

The visualization of granulomatous disease with somatostatin receptor scintigraphy

In-111 labeled pentetreotide scintigraphy was applied to three patients with proven granulomatous disease (two with sarcoidosis, one with tuberculosis). All revealed accumulation of ln-111 labeled pentetreotide in the granulomatous lesions, which was considered to be due to the presence of activated lymphocytes in these regions. This method may be of value in assessing the activity and extent of sarcoidosis and tuberculosis.

Tc-99m MIBI uptake in pulmonary sarcoidosis: preliminary clinical results and comparison with Ga-67

&NA; During tumor imaging research, the authors incidentally discovered that Tc‐99m MIBI is taken up by pulmonary sarcoidosis. In order to evaluate this uptake, they performed Tc‐99m MIBI planar and SPECT imaging in 7 patients and compared it with Ga‐67. Six out of 7 patients showed evident uptake of Tc‐99m MIBI in enlarged hilar lymph nodes. One of the patients, who had been on corticosteroid treatment, showed only faint uptake (negative result), in whom Ga‐67 uptake was seen in hilar lymph nodes although it was less evident than the uptake in the other patients. The lymph nodes were better demonstrated with Tc‐99m MIBI. The fact that enlarged hilar lymph nodes in a patient on corticosteroid treatment showed faint uptake suggests that Tc‐99m MIBI could be helpful for assessing the response to treatment. The preliminary experience in a limited number of patients showed that Tc‐99m MIBI is taken up by pulmonary sarcoidosis and it appears to be a potential alternative to Ga‐67. Further study is necessary to evaluate its ultimate role in pulmonary sarcoidosis imaging.

The effect of trimebutine maleate on gastric emptying in patients with non-ulcer dyspepsia

The study was designed to investigate the effect of trimebutine maleate, a drug used in both hyperkinetic and hypokinetic motility disorders, on gastric emptying in patients with non-ulcer dyspepsia having prolonged gastric emptying rates and to compare the parameters used for the determination of the lag period observed during the emptying of solid foods from the stomach. Gastric emptying was measured by the radionuclide technique. Twenty normal volunteers and 43 patients with non-ulcer dyspepsia participated in the study. Radionuclide imaging was performed by using a solid meal labeled with99mTc-tin colloid. Of the patients with non-ulcer dyspepsia, 20 had prolonged gastric emptying. They were given three weeks of oral treatment with trimebutine maleate and had their radionuclide gastric emptying study repeated. Treatment with trimebutine maleate resulted in reduction in duration of the lag period and less retention of food at 100 minutes (p < 0.0005). After treatment with trimebutine maleate, no significant difference has been observed in the mean symptom score of patients with prolonged gastric emptying. Among the parameters used for the determination of the lag period, lag period determined by a mathematical equation (TLAG) has been found to be longer than the lag period determined by visual inspection of the images (VLAG) and there was correlation between the two parameters when the lag time was short.

Unexpected uptake of technetium 99m hexakis-2-methoxy-isobutylisonitrile in giant lymph node hyperplasia of the mediastinum (Castleman's disease)

The case of a patient with giant lymph node hyperplasia of the mediastinum who unexpectedly showed focal uptake of technetium 99m hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) is presented in this article. The patient was included in our research programme of tumour imaging with 99mTc-MIBI because the appearance of the mass on the chest radiogram and CT scan resembled a mediastinal tumour. Final diagnosis of giant lymph node hyperplasia was achieved through histopathological examination of the surgically removed lymph node.

The comparison of dual phase Tc-99m MIBI and Tc-99m MDP scintimammography in the evaluation of breast masses : Preliminary report

The aim of this prospective study was to determine the diagnostic value of Tc-99m MDP scintimammography (SMG) for the detection of breast cancer in patients with breast masses and to compare the results with Tc-99m MIBI scintimammography. Twenty patients, categorized as suspicious, positive or benign for breast cancer according to the mammographic findings were included in the study. Dual phase Tc-99m MIBI and Tc-99m MDP SMG were performed in the prone lateral position within 5 days of each other. Although early and late Tc-99m MIBI SMG showed equal (90.4%) sensitivity, the specificity of late Tc-99m MIBI (87.5%) was found superior to early (62.5%) imaging. The overall sensitivity and specificity of early Tc-99m MDP SMG were 71.4% and 62.5%, respectively. Although late Tc-99m MDP imaging showed 100% specificity, its sensitivity was only 23.8%. In the patients with palpable masses, both early Tc-99m MDP and Tc-99m MIBI showed equal sensitivity (100%), but the sensitivity of early Tc-99m MIBI (37.5%) was found slightly higher than Tc-99m MDP (25.0%) for nonpalpable breast lesions. The sensitivity of Tc-99m MIBI and Tc-99m MDP SMG in detecting metastatic axillary involvement was 66.6% and 50%, respectively. High sensitivity and specificity together with its low cost, easy availability and the possibility of detecting bone metastases seems to make Tc-99m MDP a contributive agent in the evaluation of breast lesions as an alternative to Tc-99m MIBI.

Role of bone scanning in the management of non-united fractures: a clinical study

Technetium-99m methylene diphosphonate (99mTc-MDP) bone scintigraphy was performed in 45 patients (42 male and 3 female) with established non-united fractures to predict the healing response to pulsing electromagnetic field stimulation therapy. The bone scans revealed 3 different scintigraphic patterns. The most frequent pattern was an increased uniform uptake of the tracer at the non-union site (group 1). The second pattern was increased activity at the bone ends with a photon-deficient area between the fracture sites (group 2a) or a generalized decrease in the radionuclide concentration in the region of bone fragments (group 2b). When the scintigraphic pattern did not fit either of the two patterns or when the presence of the cold area between the bone fragments could not be judged with certainty, it was called indeterminate (group 3). All patients underwent pulsing electromagnetic field stimulation. The healing rate was 87.5% and 42.8% in group 1 and group 3 patients, respectively. None of the group 2 patients had any evidence of healing, and they all underwent surgical exploration, revealing complicated non-unions. We conclude that 99mTc bone scintigraphy is a useful tool in determining complicated non-unions and selecting the proper therapy mode.