Evaluation of the skull base by SPECT. A comparison with planar scintigraphy and computed tomography

Computed tomography is currently the standard diagnostic tool for the evaluation of the skull base. The complex anatomy of this area is the primary reason why planar bone scintigraphy is often unsatisfactory; exact localization of abnormalities may be very difficult. These limitations may be overcome by SPECT. Seventeen patients with clinical features of basal skull involvement were assessed by CT, SPECT, and planar scintigraphy. Subsequent clinical diagnoses were malignancy in 15 patients, vasculitis in 1 patient, and osteomyelitis in 1 patient. Computed tomography with IV contrast was performed through the skull base at 5 mm intervals. Planar scintigraphy with Tc-99m MDP was followed by SPECT. Bony involvement compatible with the clinical findings was demonstrated by CT scans in 6 patients, by planar scintigraphy in 7 patients, and by SPECT in 9 patients. The abnormalities that were identified by CT were all identified by SPECT. This study suggests that, in imaging the skull base, SPECT is more sensitive and provides better anatomical localization than planar imaging and appears useful in patients with a negative CT study.     

99mTc-HMPAO labeled leukocyte SPECT in intracranial lesions

BACKGROUND: Scintigraphy with 111In (indium-111)-oxine or 99mTechnetium-hexamethylpropyleneamine oxime (99mTc-HMPAO) labeled leukocytes has been used to differentiate brain abscess from brain tumor. However, there are false positive or false negative results from planar scintigraphic images. So a more specific and sensitive scintigraphic technique needs to be developed. METHODS: Planar and single photon emission computed tomography (SPECT) images were obtained and reviewed in 14 patients with intracerebral ring-enhancing lesions on computed tomography (CT) or magnetic resonance imaging (MRI). In all patients, diagnosis was confirmed by histopathologic examination. The effect of steroids or antibiotics on scintigraphic finding was examined. RESULTS: Abscess was confirmed in six patients, tumor in six, tuberculoma and cysticercosis in one each, respectively. In all the patients with abscess, SPECT showed increased focal activity irrespective of steroid or antibiotic therapy. Increased radioactivity, which could not be detected on planar images, could be identified in two patients with abscess. In three of the six patients with tumor, radiolabeled leukocytes did not accumulate in the tumor. In the other three patients with tumor, SPECT showed focally increased activity that was less intense than the activity shown in the patients with abscess. CONCLUSIONS: 99mTc-HMPAO labeled leukocyte SPECT is useful for the differential diagnosis of intracerebral ring-enhancing lesions, and the use of steroids or antibiotics does not influence the sensitivity of SPECT. Diagnostic sensitivity of scintigraphy with labeled leukocytes could be improved by SPECT in addition to planar image.     

123I-metaiodobenzylguanidine (MIBG) scintigraphy for the staging of neuroblastoma

Nineteen children with neuroblastoma (aged 2 w.-7 y.o.) were studied to evaluate the optimal scan conditions for Iodine-123-Metaiodobenzylguanidine (MIBG) scintigraphy for accurate staging at the time of diagnosis. Six and 24 hours after an injection of 123I-MIBG, whole body image and truncal spot and SPECT images were obtained. Compared with other studies (CT or MRI and bone scintigraphy), each 123I-MIBG image was evaluated visually to investigate which image can demonstrate the extent of neuroblastoma most exactly. MIBG images demonstrated primary tumors in all patients, and metastatic lymphadenopathy in 8 of 9 patients. Twenty-four hour SPECT images gave us the most detailed information about the extent of abnormal accumulation. As to bone and bone marrow lesions, 6 hour images were superior to 24 hour images in detectability. Moreover, MIBG showed many more lesions and more extended accumulation than the bone scan. 123I-MIBG scintigraphy was very useful in detecting neuroblastomas. In order to get the most valuable information, both delayed SPECT and early whole body planar images should be obtained.     

111In octreotide scintigraphy in the evaluation of head and neck lesions

PURPOSE: To evaluate indium 111 octreotide scintigraphy for the detection of suspected neuroendocrine lesions of the head and neck. METHODS: After receiving 6 mCi of 111In octreotide, 22 patients with suspected lesions of the head and neck were examined with both planar and single-photon emission CT (SPECT). Static images, obtained at 4 hours, included the head/neck, chest, abdomen, and pelvis. Additional SPECT images were obtained at 4 or 24 hours. Studies were compared with available conventional radiologic examinations (12 CT, 11 MR, and three angiographic studies) as well as with clinical and pathologic findings. RESULTS: Eighteen of the 22 patients had abnormal findings at scintigraphy. Eleven paragangliomas were seen in 10 patients, metastatic medullary thyroid carcinoma in three patients, thyroid adenoma in two patients, and Merkel cell tumor, carcinoid, and plasmacytoma in one patient each. Surgical confirmation was available in 13 patients. The smallest lesion detected was 1.5 cm. There was one false-positive and one false-negative examination. CONCLUSION: 111In octreotide scintigraphy is a useful imaging tool for the detection of primary and metastatic neuroendocrine tumors of the head and neck that are larger than 1.5 cm. This technique enables distinction of glomus tumors from other masses (such as neuromas) and can be used in the postoperative setting to distinguish scar from recurrent paraganglioma. Since it is an examination of the entire body, it has great utility for detecting multicentric paraganglioma and for screening patients with familial paraganglioma.     

Technetium-99m-MIBI and thallium-201 scintigraphy of primary lung cancer

We evaluated the usefulness of 99mTc-MIBI scintigraphy in primary lung cancer in comparison with 201Tl-chloride scintigraphy. METHODS: There were 45 patients with primary lung cancer. All patients underwent dual-isotope imaging with 201Tl-chloride and 99mTc-MIBI. Regions of interest were placed over the tumors (T) and contralateral normal lung tissue (N) on one coronal view in the SPECT, and T/N ratio and retention index were calculated. RESULTS: The positive rate was 98% in both the early and delayed images for 201Tl-chloride and 96% in the early and 89% in the delayed image for 99mTc-MIBI. Both early and delayed T/N ratios for 201Tl-chloride were higher than those for 99mTc-MIBI. There was no significant correlation between T/N ratio and histological type of tumor in both images. However, in both images, there was a tendency for the early and delayed ratios to increase as the tumor diameter became larger. The retention index of 201Tl-chloride was higher than that of 99mTc-MIBI. There were no significant differences in the retention index with respect to the histological type and tumor size. CONCLUSION: The results of this preliminary clinical study suggest that 99mTl-MIBI can depict primary lung cancer similar to 201Tl-chloride. However, T/N ratio and retention index of 99mTc-MIBI in the tumor areas are significantly lower compared with those of 201Tl-chloride.     

Interleukin-2 production by human pre-implantation embryos

We performed a double-phase Tc-99m-SestaMIBI SPECT study on a patient who presented with a mass located at the skull base. The results were compared with double-phase T1-201 SPECT study. Early phase (30 min) SPECT images of both radiopharmaceuticals demonstrated increased radiotracer uptake in the region of the tumor. However, late images (180 min) revealed rapid wash-out of Tc-99m-SestaMIBI from the tumor, suggestive of a benign vascular tumor, while T1-201 images showed slower wash-out. Tc-99m-SestaMIBI SPECT findings were also confirmed by carotid angiography and biopsy, while a contemporaneous MRI scan was inconclusive in differentiating benign from malignant tumor. Initial and one-year follow-up whole body CT scans were negative for any metastatic sites, supporting the diagnosis of benign glomus jugulare tumor.     

Accumulation of Tc-99m MIBI in breast lymphoma: comparison with Ga-67 citrate

We report 2 cases of malignant lymphoma of the breast which were clearly shown on total body imaging as well as on SPECT with Ga-67 and Tc-99m MIBI. Tumor accumulation of Ga-67 was seen in all cases including a recurrent tumor. Ga-67 scintigraphy is useful for follow up in detecting relapse, as well as in predicting responses to therapy. Tc-99m MIBI was found to accumulate in the malignant lymphoma of the breast, and especially SPECT images of breast lesions provided better contrast than planar images, and Tc-99m MIBI SPECT could diagnose localization of the tumor because there was no uptake by the breast. But the Tc-99m MIBI accumulation of the tumor was lower than Ga-67.     

Superimposition of In-111 platelet SPECT and CT/MR imaging in intracardiac thrombus

An initial attempt to superimpose in-111-labeled platelet SPECT over CT/MRI in two patients with intracardiac thrombus is presented. One patient was a 65-year-old woman with a history of mitral and tricuspid valve replacement. This patient had a large thrombus measuring 74 x 43 x 34 mm in the right atrium. Fusion imaging with CT showed increased in-111 activity on the surface of the thrombus, which was visualized as circular activity on a planar image. The other patient was a 72-year-old woman who had a thrombus measuring 17 x 14 x 12 mm at the cardiac apex. Planar imaging showed two discrete areas of abnormal in-111 activity. Superimposition of the SPECT image over MR revealed that one of these areas corresponded to the small thrombus, whereas the other related to a previous subendomyocardial biopsy. In both patients, the activity ratio of the abnormal in-111 accumulation versus the cardiac chamber on SPECT was greater than that on planar images. The correlation of in-111 platelet SPECT and CT/MRI was useful in accurately localizing the intracardiac thrombus.     

Sixty adrenal masses of large dimensions: hormonal and morphologic evaluation

OBJECTIVES: To evaluate the nature and function of adrenal masses of large dimensions (macrotumors). METHODS: Sixty consecutive patients (31 women, 29 men, age range 15 to 84 years) with adrenal masses 4.0 cm in diameter or larger (range 4.0 to 15.0 cm) underwent morphologic study by computed tomography (CT); the majority also underwent 131-I-6beta-norcholesterol (131I-NC) or 131I-MIBG scintigraphy. Basal evaluation of glucocorticoids, mineralcorticoids, and catecholamines was performed in all patients, and in 38 cases determination of androgens was also made. In addition, on the basis of various clinical suspicions, a dynamic hormonal study was performed. RESULTS: Macrotumors were benign in 78.3% of cases and included pheochromocytomas (n = 17), nonfunctioning cortical adenomas (n = 12), and cortisol-secreting tumors (n = 7, Cushing's syndrome). Malignant forms were 21.7% of the total, including pheochromocytomas (n = 3), cortical carcinomas (n = 6), and metastases (n = 4). On CT, malignant masses were larger (8.4+/-0.9 cm) than benign ones (5.7+/-0.3 cm) (P < 0.0001) and the mass size was strictly related to malignancy (P < 0.03). CT did not offer other diagnostic criteria for malignancy, except irregular margins and regional lymph node enlargement, which were more frequently (P < 0.0001) found in malignant forms. 131I-MIBG scintigraphy showed tracer uptake in all pheochromocytomas, both benign and malignant. By contrast, on 131I-NC scintigraphy, cortical malignancies never accumulated the radiotracer, whereas uptake was observed in all cases of solid cortical benign adenomas. Patients with cortical carcinomas showed plasma sex steroids above the normal range, pheochromocytomas were asymptomatic in 15% of cases, and almost half of the patients with Cushing's syndrome did not show clinical features of the disease (pre-Cushing's syndrome). CONCLUSIONS: Adrenal macrotumors frequently show endocrine activity and the medulla seems to be involved more than the cortex. Pheochromocytomas and cortisol-secreting adenomas are sometimes asymptomatic. Malignancy is often found in macromasses and, at least for the cortical forms, size of the tumor on CT, 131I-NC uptake on scintigraphy, and determination of levels of sex steroids seem to be useful criteria for predicting the nature of the mass.     

Three-window transformation cross-talk correction for simultaneous dual-isotope imaging

A newly developed cross-talk correction method for simultaneous dual-isotope SPECT imaging was tested in a canine model. The method is based on the assumption that the transformations, which modify the primary energy window images into the scatter images as viewed in the other energy windows, are known. These transformations were found by measuring the point spread functions (PSFs) in two different energy windows for both isotopes in water. The dual-isotope correction method is described by two convolution equations which were applied in frequency space. The equations take into account the different spatial distributions of the primary and scatter cross-talk photons. The new enhancement of the method was in applying restoration filters to the resulting corrected images. Three separate studies were acquired in our dog study: two single-isotope and one dual-isotope study. The single isotope images were used as references. The contrast between the left ventricle cavity (LVC) and the myocardium was used in transaxial and short-axis slices as a parameter to evaluate results of dual-isotope correction method with restoration. The change in contrast in the dual-isotope corrected images in both energy windows, i.e., Tc-99m primary window (140 keV) and Tl-201 primary window (70 keV), was significant. The only exception was for the short-axis Tc-99m window images. The corrected 140 keV dual-isotope short-axis slice had the contrast of 0.60 vs 0.58, which was the value in the noncorrected dual-isotope short-axis slice. For dual-isotope 140 keV transaxial slice, the contrast changed from 0.72 to 0.82 after correction. In comparison, for single-isotope Tc-99m 140 keV transaxial slice, contrast changed from 0.62 to 0.84 after restoration correction. There was less change in contrast in the short-axis Tc-99m 140 keV slice, i.e., from 0.56 to 0.61. In the Tl-201 primary window for the transaxial slices the improvement of contrast was from 0.38 to 0.64, and for short-axis slices from 0.22 to 0.32 after correction. In the same 70 keV energy window for single-isotope Tl-201 images, contrast improved from 0.61 to 0.69 and from 0.35 to 0.38 for transaxial and short-axis slice, respectively, after applying restoration correction. In conclusion, the presented dual-isotope correction method with restoration improves the quality of the simultaneous rest Tl-201/stress Tc-99m sestamibi SPECT imaging.     

Adrenocortical SPECT using iodine-131 NP-59

Adrenal scintigraphy with 131I-labeled 6-beta-iodomethyl-19-norcholesterol (NP-59) is a technically demanding and complex procedure. However, it can provide crucial and unique information about the functional status of the adrenal glands and guide the appropriate therapeutic management of patients with biochemically proven disease. Since the introduction of this new investigational drug, scintigraphic imaging has been performed using conventional planar techniques. We present an interesting case of primary aldosteronism in which planar scintigraphy and SPECT were combined in an attempt to increase the sensitivity of the study. SPECT revealed scintigraphic evidence of bilateral adrenocortical hyperplasia. Interestingly, the CT scan of this patient showed only an equivocal abnormality in the left adrenal gland, suggestive of an adenoma.     

Iodine-123-MIBG SPECT versus planar imaging in children with neural crest tumors

Iodine-123-metaiodobenzylguanidine (MIBG) SPECT was compared with 123I-MIBG planar imaging in 35 studies of 25 children with neural crest tumors. METHODS: Iodine-123-MIBG (0.070-0.140 mCi/kg intravenously) was followed at 24 hr by wholebody planar imaging and triple-detector, high-resolution thoraco-abdominal SPECT. At 48 hr, thoracoabdominal planar imaging was performed whenever a high-tissue background or gut activity interfered with the interpretation of the 24-hr planar images. SPECT views included a cine loop presentation of multiple volume-rendered projections. Two reviewers enumerated the number of abnormal sites on the planar and SPECT studies and rated the certainty of interpretation for each study on a scale from 0.1 (low certainty) to 1.0 (high). RESULTS: Abnormal uptake was noted on planar or SPECT imaging in 13 studies (seven patients). The average number of abnormal sites detected per study for all 35 studies was 2.7 for planar imaging and 2.9 for SPECT (p = not significant) (and 7.2 and 8.4 for planar and SPECT, respectively, for the 13 abnormal studies.) The certainty ratings for all 35 studies were 0.74 for planar studies, 0.82 for SPECT (p = 0.05, chi-square, compared with planar) and 0.86 for planar and SPECT combined (p = 0.01 compared with planar alone). On volume-rendered images, gut activity was seen as diffuse and/or linear intraluminal activity. CONCLUSION: When 123I-MIBG SPECT is used, the number of lesions detected is not increased, but there is a significant improvement in the certainty of interpretation over planar imaging.     

The mammalian homologue of mago nashi encodes a serum-inducible protein

OBJECTIVE: We prospectively compared the ability of two techniques--bone scintigraphy with single-photon emission computed tomography (SPECT) of the chest and CT of the chest--to reveal potential osteosarcoma metastases of the lung. SUBJECTS AND METHODS: Our study included 27 patients with osteosarcoma who prospectively underwent both bone scintigraphy with SPECT of the chest and CT of the chest. The imaging results were compared with outcome or pathologic analysis of any lung lesions found. RESULTS: Eight (30%) of the 27 patients had pulmonary metastases. Four of these eight patients had positive results on both CT studies and bone SPECT studies, with additional lesions detected with bone SPECT in two of these four patients. The other four patients with pulmonary metastases had positive results on CT studies, whereas the results of bone SPECT studies remained negative. The results of bone SPECT studies were negative in the 19 patients without pulmonary metastases. CT, however, showed abnormalities in seven (37%) of the 19 patients, which were eventually attributed to benign conditions. CONCLUSION: Negative results on a bone SPECT study of the chest should not be used to exclude the possibility of lung metastases. However, if the results are positive, a bone SPECT study can be used to confirm abnormalities seen on CT scans and may also reveal subtle lesions missed on CT scans.     

Computer-stimulated test fitting of an implantable hearing aid using implantable hearing aid using three-dimensional CT scans of the temporal bone: preliminary study

In preparation for future implantation of the implantable middle ear transducer in patients, a method was sought for preoperatively test fitting a model of the device, using computer generated three-dimensional (3-D) temporal bone images derived from spiral computed tomography (CT) data. A 3-D model of the implantable middle ear transducer was designed using NIH Image software on a Macintosh computer. High resolution human temporal bone CT scans were obtained using a spiral CT scanner (Siemens Somatom Plus S). The 3-D transducer model was superimposed onto 3-D reconstructions of the temporal bone using ANALYZE software on a computer graphics workstation (Sun SPARCstation 10), showing the transducer "implanted" in the temporal bone. Measurements were validated using a cadaver temporal bone. This process produced images demonstrating the "fit" of the current transducer design in the mastoid region of the adult temporal bone. It permitted assessment of the proximity of surrounding structures such as the external auditory meatus, dura, or sigmoid sinus. Preliminary cadaver validation measurements confirmed the accuracy of this method. Three-dimensional CT is a feasible method for preoperative planning of the surgical implantation of devices in the temporal bone. This method of 3-D test fitting will be used in the future to determine optimum orientation and size limitations for human implantable devices.     

Technetium-99m-MIBI in primary and recurrent head and neck tumors: contribution of bone SPECT image fusion

We prospectively investigated 200 patients with the clinical suspicion for head and neck tumors. The final diagnoses were 94 primary and 56 (37 confirmed, 19 excluded) recurrent squamous cell carcinomas (SCCs), 3 primary and 7 (4 confirmed, 3 excluded) recurrent adenoid cystic carcinomas (ACCs), 6 non-Hodgkin's lymphomas, 10 distant metastases, 6 other malignancies, 10 inflammatory and 8 other nonmalignant conditions. METHODS: Bone (600 MBq 99mTc-3,3-diphosphono-1,2-propane dicarboxylic acid tetrasodium salt) and hexakis-2-methoxyisobutyl isonitrile (MIBI) (600 MBq 99mTc-MIBI) SPECT were both performed under identical conditions (triple-head gamma camera; ultra-high-resolution, parallel-hole collimators; three-dimensional postfiltering) and judged independently and after superimposition. The results were compared to the results of biopsy, surgery and CT. RESULTS: The overall sensitivity/specificity of MIBI was 90%/78% for tumor detection and 90%/95% for the identification of malignant lymph node involvement (CT: 79%/66%, respectively 90%/79%). In the subgroup of recurrent SCC and ACC the sensitivity/specificity for tumor detection was 95%/71% for MIBI versus 78%/68% for CT. The isolated assessment of bone SPECT had a sensitivity/specificity of 100%/17% for osseous tumor spread. Image fusion of MIBI and bone SPECT differentiated between regio-local bone involvement and inflammatory changes and increased the specificity of bone SPECT to 100% in primary staging. Tumor size, stage, histology and pretreatment had no statistically significant effect on tracer uptake or diagnostic utility of scintigraphy. CONCLUSION: We propose the combined 99mTc-MIBI and bone ultra-high resolution SPECT as a highly useful imaging approach in the primary and secondary staging in patients with suspected malignancies in the head and neck region. The high specificity for malignancies in the head and neck region may be used in the differential diagnosis between head and neck malignancies and inflammatory disease in patients with the accidental finding of enlarged lymph nodes and no clinical signs of a primary tumor. Image fusion with bone scanning is mandatory for the topographical orientation and increases the specificity of bone scanning to differentiate between inflammatory or malignant causes of increased bone metabolism.     

Radiolabeled somatostatin analog scintigraphy in differentiated thyroid carcinoma

After intravenous administration of a radiolabeled somatostatin analog (octreotide), an image of the thyroid gland is frequently observed; few data are available, however, on somatostatin receptors in epithelial thyroid cells assessed in vitro and on images of differentiated thyroid carcinoma (DTC) with pentetreotide scintigraphy. METHODS: In four patients with metastatic thyroid carcinoma, whole-body scintigraphy was performed 4 to 48 hr after injection of 110 MBq of 111In-pentetreotide. The results were compared to data obtained with other imaging modalities, including scintigraphy performed after administration of a therapeutic dose of 131I. RESULTS: There were positive foci in distant metastases on 111In-pentetreotide scintigraphy. Pentetreotide scintigraphy was positive in two patients with an "insular" form of DTC, one of whom had a positive (faintly) 131I scan. Of the other two patients with papillary DTC without radioiodine uptake, only one exhibited a certain degree of pentetreotide scintigraphy positivity in distant metastases. CONCLUSION: These results show promise for exploration of insular thyroid carcinoma and suggest that these carcinomas may possess functional differentiation features, including somatostatin receptors.     

Anti-CEA immunoscintigraphy might be more useful than computed tomography in the preoperative thoracic evaluation of lung cancer. A comparison between planar immunoscintigraphy, single photon emission computed tomography (SPECT), and computed tomography

While a clinical, plain radiographic, and bronchoscopic assessment yields most of the essential information needed in lung cancer, computed tomography (CT) of the thorax provides diagnostic information previously unobtainable, potentially capable of reducing the number of explorative thoracotomies. In a few recent studies, immunoscintigraphy with anti-carcinoembryonic antigen (anti-CEA) monoclonal antibodies (MA) has shown remarkable staging potential. To compare the diagnostic accuracy of the two techniques, we photoscanned with indium-111 (111In)-labeled-F(ab')2 fragments of the murine anti-CEA MA FO23C5 45 patients, who were pathologically assessed for possible loco-regional extension of lung cancer. Both planar and single photo emission computed tomography (SPECT) images were obtained. Additionally, CT of the thorax (contiguous CT slices, 10 mm thick, from the lung apices to the upper abdomen), and other routine tests of preoperative evaluation were obtained. On the basis of 37 (N1, T3, and T4), 38 (N2), and 12 (N3) pathologically documented sites, an accuracy of 65, 76, 92, 78, and 86 percent (SPECT images), and 62, 68, 42, 78, and 84 percent (CT images) was calculated (figures are relevant to N1, N2, N3, T3, and T4 disease, respectively). Thus, both techniques shared a significant margin of error in almost all the categories of evaluation; however, immunoscintigraphy showed equivalent, and, in the lymph node assessment, superior results to CT. A marginal improvement of diagnostic accuracy was recorded combining the three techniques in one case (SPECT plus planar immunoscintigraphic images), while there was no benefit in any possible integration of CT and immunoscintigraphic images. In patients with peripheral nonsquamous cell cancers, the accuracy of anti-CEA immunoscintigraphy was of 90 percent or higher. Variations in the modality of performing immunoscintigraphy, such as changes in the dose of antibody fragments to be injected, in the percentage of radiolabeling, or in the time of imaging, affected the quality of immunoscintigraphic series, and the consequent interpretation of findings. At the present time, there are very few reliable tests capable of selecting patients to proceed directly to thoracotomy or to receive some intermediate surgical test, such as a prior mediastinoscopy. Traditionally, CT has been this type of "filter-test." If current findings will be confirmed in future studies, anti-CEA immunoscintigraphy might replace CT in the evaluation of particular subgroups of patients, such as patients with peripheral nonsquamous cell bronchogenic carcinoma.     

Iodine-131-metaiodobenzylguanidine dosimetry in cancer therapy: risk versus benefit

In the treatment of neural crest tumors, such as pheochromocytoma, with[131I]MIBG, bone marrow toxicity limits the amount of administered activity and, thus, a therapeutically useful tumor dose. METHODS: We calculated tumor doses in a series of diagnostic studies with [123I]MIBG using accurate quantification of SPECT and planar scintigraphy. By extrapolating diagnostic results to therapeutic activities of [131I]MIBG, we could compare the results with whole-body doses from a series of therapies. RESULTS: The tumor dose was DT = 2.2 mGy MBq(-1) (median value of 27 measurements, range 0.04 < or = DT < or = 20 mGy MBq(-1) and the whole-body dose in a series of 16 patients undergoing 50 therapies was DWB = 0.12 +/- 0.04 mGy MBq(-1) (mean +/- s.d.). The therapeutic ratio varied between 130 to below 10 in some patients. CONCLUSION: The results were compared with published data. We found clearly skewed distribution of tumor doses, with a majority of tumors receiving only a few mGy per MBq administered activity. In some patients, however, doses did reach 20 mGy MBq(-1).     

Clinical value of triple-energy window scatter correction in simultaneous dual-isotope single-photon emission tomography with 123I-BMIPP and 201Tl

To improve the image quality in simultaneous dual-isotope single-photon emission tomography (SPET) with iodine-123 labelled 15-(p-iodophenyl)-3-methylpentadecanoic acid (BMIPP) and thallium-201, we applied the triple-energy window method (TEW) for correction of the cross-talk and scatter artifact. Seventy-one patients with coronary artery disease were included. 201Tl cross-talk into the 123I acquisition window (group 1, n = 30) and 123I cross-talk into the 201Tl window (group 2, n = 41) were studied. In group 1, 123I images were first obtained (single-isotope images), followed by 201Tl injection and SPET acquisition using dual-isotope windows (dual-isotope images). In group 2, the order was reversed. The dual-isotope SPET images with and without TEW were compared with the single-isotope images. Qualitative evaluation was performed by scoring the segmental defect pattern. Detectability of the mismatched fatty acid metabolism on dual-isotope SPET was evaluated by receiver operating characteristic (ROC) curve analysis. Segmental defect pattern agreement between dual and corrected single images was significantly improved by TEW correction (P<0.01). The agreement was particularly improved in segments with absence of uptake. There was no significant difference between TEW-corrected dual-isotope SPET and corresponding single-isotope SPET with regard to either % defect count or background activity. Mismatched fatty acid metabolism depicted by dual-isotope SPET predicted abnormal wall motion more accurately with TEW than without TEW. With TEW, a practical method for scatter and cross-talk correction in clinical settings, simultaneous dual 123I-BMIPP/201Tl SPET is feasible for the assessment of myocardial perfusion/metabolism mismatch.     

99m-Tc-MIBI SPECT parathyroid gland scintigraphy for the preoperative localization of small parathyroid gland adenomas

AIM: It was the of this study to assess the value of the 99mTc-MIBI scintigraphy in SPECT technique in the preoperative lateral location of small parathyroid adenoma (PTA). METHODS: 25 consecutive patients (8 male, 17 female, mean age 63 +/- 13 years) with the established diagnosis of primary hyperparathyroidism and non-diagnostic ultrasonography were scanned preoperatively. After a thyroid examination to exclude radionuclide accumulating thyroid adenoma, planar and tomographic images were acquired 20 min. and 120 min. after i.v. injection of 740 MBq 99mTc-MIBI using a 3 head gamma camera (Picker Prism 3000). The first 10 patients underwent an additional 201Tl/99mTc subtraction scintigraphy in a 2 days protocol. RESULTS: All patients had small, solitary PTA (< 1 g). 201Tl/99mTc subtraction scintigraphy (n = 10) showed only a sensitivity of 50%. Using planar MIBI-scintigraphy lateral location of PTA was possible in 18 cases (sensitivity: 72%). There was an increase in sensitivity up to 96% using the SPECT technique and the 3D display (volume-rendered reprojection). CONCLUSION: In contrast to 201Tl/99mTc subtraction scintigraphy, which showed only a low sensitivity, a reliable lateral location of small PTA was obtained using the tomographic 99mTc-MIBI scintigraphy. This method offers e.g. the possibility for the surgeon to perform an unilateral parathyroidectomy.