Increased iodine-123-iodoamphetamine uptake in hepatomas

In the current study, two cases of hepatoma are reported in which N-isopropyl-(I-123)-p-iodoamphetamine (IMP) liver scan demonstrated increased accumulation in the tumor corresponding to the areas enhanced on contrast enhanced CT (CE-CT). In contrast, there was no IMP accumulation in the necrotic area of the tumor in which no enhancement was found on CE-CT. Thus, IMP liver scan seems to have the potential to assess the viability of a hepatoma as well as to detect and localize it.     

Effects of visual stimulation on the redistribution of iodine-123-IMP in the brain using SPECT imaging

A study was performed to validate the assumption that redistribution and clearance of [123I]IMP localization in the brain are unaffected by changes in ambient light levels and visual stimulation occurring after radiopharmaceutical is administered and deposited in the brain. Serial SPECT and planar imaging studies were performed on six healthy, volunteer, adult male subjects under resting, nonactivation conditions. Studies were repeated 7 days later with each subject exposed to strobe light stimulation prior to delayed SPECT procedures at 3 hr. Redistribution and clearance of 123I-IMP in the brain were examined in cortical, subcortical, and cerebellar regions on transaxial slices for the two sets of serial procedures in each subject. Visual stimulation following the initial uptake of [123I]IMP did not affect the distribution or clearance of [123I]IMP in the brain, including the visual cortex, and therefore should not influence the interpretation of delayed SPECT images.     

Delayed lung scintigraphy with N-isopropyl-I-123-p-iodoamphetamine in lung cancer and inflammatory disease

Lung studies with N-Isopropyl-I-123-p-Iodoamphetamine (IMP) were performed on patients with lung cancer or inflammatory disease. In the present study, we evaluated the usefulness of the delayed scintigraphy. The subjects consisted of 27 patients with lung cancer (34 lesions), 3 with radiation pneumonitis, 2 with interstitial pneumonitis, 2 with old tuberculous lesion (tuberculomas), 1 with diffuse panbronchiolitis, 1 with pneumonia and 1 with lung abscess. The delayed scintigraphy was performed 24 hr after intravenous injection of 3 mCi IMP, in sitting position. In 10 patients, SPECT images were obtained following the delayed scintigraphy. Delayed scintigraphic appearances of lung cancer were classified into 5 types, high IMP uptake in the area congruent with the lesion of atelectasis and/or obstructive pneumonia (Type I), high IMP uptake in the area surrounded the tumor (Type II), a defect in the area consistent with the tumor and no high IMP uptake in the area surrounded the tumor (Type III), high IMP uptake in the area almost congruent with the tumor (Type IV) and no significant change (Type V). Excluding 10 lesions with Type IV or V, no IMP uptake was seen in the areas congruent with the tumors. Type II was the most frequently observed pattern. Normal scintigrams (Type V) were observed in 8 lesions, whose sizes were fairly small. There was no definite trend caused by difference in histological types of cancers. In 8 patients with viable inflammatory disease of the lung, the delayed scintigrams showed high IMP uptake in the areas congruent with the abnormalities on chest roentgenograms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potential use of iodine-123 metaiodobenzylguanidine radioaerosol as a marker of pulmonary neuroadrenergic function

Iodine-123 metaiodobenzylguanidine (¹²³IMIBG) radioaerosol is of potential use in the investigation of the neuroadrenergic function of the lungs; however, before the method can be successfully employed the following issues need to be clarified: (1) Does the nebulization affect the radiochemical purity of¹²³IMIBG? (2) Is the pulmonary distribution of inhaled¹²³IMIBG homogeneous in normal subjects? (3) Does the pulmonary clearance of inhaled¹²³I-MIBG reflect the functional status of the neuroadrenergic system of the lungs? In this study we performed: (1) a chromatographic study of nebulized¹²³I-MIBG; (2) a quantitative evaluation of the lung distribution of¹²³I-MIBG radioaerosol in normal subjects as compared with that of technetium-99m diethylene triamine penta-acetic acid (^99mTc-DTPA) and (3) an assessment of¹²³I-MIBG lung clearance both under control conditions and after pharmacologically induced beta-blockade, again compared with^99mTc-DTPA. For these purposes, eight normal subjects were divided randomly into an “MIBG group” and a “DTPA group” (four subjects each) and submitted to three scintigraphic studies each: a baseline study, and studies after the administration of a low (80 mg) and a high (160 mg) dose of propranolol. Radiochemical purity of nebulized¹²³IMIBG ranged between 97.18% and 98.70%. The lung distribution of¹²³I-MIBG, as judged by the aerosol penetration index, was identical to that of^99mTc-DTPA under all study conditions. The¹²³I-MIBG clearance rate was slower than that of^99mTc-DTPA under baseline conditions (135±32 min vs 69±27 min,P<0.01) and increased significantly after propranolol administrations, while the^99mTc-DTPA clearance did not change. The following conclusions were drawn: (1) the nebulization does not affect the radiochemical purity of¹²³I-MIBG; (2) the lung distribution of¹²³I-MIBG is homogeneous in normal subjects; (3) the pulmonary clearance of¹²³IMIBG reflects the functional status of the neuroadrenergic system of the lungs. Thus this scintigraphic method is suitable for research and perhaps for future clinical use.     

Potential of iodine-123 metaiodobenzylguanidine single-photon emission tomography to detect abnormal functional status of the pulmonary neuroadrenergic system in irradiated lung

The potential of iodine-123 metaiodobenzylguanidine (MIBG) to detect functional abnormalities of the pulmonary neuroadrenergic system (PNS) in irradiated lung areas (ILAS) was preliminarily explored using single-photon emission tomography (SPET). The subjects included five healthy subjects and a total of 31 patients with peripheral-type lung cancer treated by radiation; 15 patients (group A) had received a dose of less than 36 Gy (mean ± SD: 28.2 ±6.2 Gy), and 16 patients (group B) had received a higher dose (mean ± SD: 51.2 ± 3.5 Gy) at the time of examination. MIBG SPET scans aquired 15 min and 3 h after injection were used to measure the MIBG uptake ratio (count ratio of the ILA to the contralateral non-ILA) and the clearance rate [percentage of (early counts – delayed counts)/early counts] from the ILAs without noticeable abnormal opacities on chest computed tomography scan. Lung perfusion changes were also assessed by technetium-99m macroaggregated albumin SPET. By contrast to the homogeneous MIBG uptake in the lungs of the healthy subjects, MIBG uptake was folcally decreased in correspondence with the ILAs in all patients, including 11 patients (73.3%) of group A with relatively preserved lung perfusion. The reduction MIBG uptake was significant (P<0.0001), and the MIBG clearance rate from the ILAs was also significantly faster than the clearance rates from the normal lungs and contralateral non-ILAs (both P<0.01). Group B patients showed significantly lower MIBG uptake and faster clearance from the ILAs than group A patients (P<0.001 and P<0.05, respectively), although there was no significant difference in the clearance from the non-ILAs. Overall, MIBG uptake/clearance from the ILAs correlated significantly with the radiation dose in the 31 patients (r = –0.656; P<0.0001 and r = 0.387; P<0.05, respectively). Perfusion changes were inversely correlated with the clearance from the ILAs (r = –0.432, P<0.05), but did not correlate with MIBG uptake. These preliminary results suggest that MIBG may have the potential to be a marker of abnormal functional status of the PNS produced by irradiation and may facilitate investigation of irradiation lung injury independently of morphological or lung perfusion changes. Received 11 December 1998 and in revised form 10 February 1999     

Influence of age and gender on iodine-123 MIBG kinetics in normal lung

Materials and Methods

Seventeen healthy volunteers and 14 patients with no cardiac or pulmonary disorders were included in this study (age range: 24 to 88 years, mean age 50.2 ± 17.6 years; 16 males, 15 females). Planar images were obtained 15 min (early) and 3 h (delayed) after injection of I-123 MIBG (111 MBq). Pulmonary uptake of I-123 MIBG was quantified based on the lung-to-mediastinum ratio (LMR) on early and delayed images. The lung clearance rate (LCR) was calculated from both the early and delayed images.

Results

Both early and delayed LMR values increased slightly, although they showed no significant correlations with age. There was a significant inverse correlation between LCR and age (r = ?0.57, p < 0.001). Neither LCR nor LMR differed significantly between male and female patients, but the mean age of the men was lower than that of the women.

Conclusions

Pulmonary I-123 MIBG kinetics may reflect age-dependent changes in NE metabolism. The effects of age should be taken into account when assessing pulmonary NE metabolism with I-123 MIBG.     

Potential of iodine-123 metaiodobenzylguanidine single-photon emission tomography to detect abnormal functional status of the pulmonary neuroadrenergic system in irradiated lung.

The potential of iodine-123 metaiodobenzylguanidine (MIBG) to detect functional abnormalities of the pulmonary neuroadrenergic system (PNS) in irradiated lung areas (ILAS) was preliminarily explored using single-photon emission tomography (SPET). The subjects included five healthy subjects and a total of 31 patients with peripheral-type lung cancer treated by radiation; 15 patients (group A) had received a dose of less than 36 Gy (mean +/- SD: 28.2 +/-6.2 Gy), and 16 patients (group B) had received a higher dose (mean +/- SD: 51.2 +/- 3.5 Gy) at the time of examination. MIBG SPET scans acquired 15 min and 3 h after injection were used to measure the MIBG uptake ratio (count ratio of the ILA to the contralateral non-ILA) and the clearance rate [percentage of (early counts - delayed counts)/early counts] from the ILAs without noticeable abnormal opacities on chest computed tomography scan. Lung perfusion changes were also assessed by technetium-99m macroaggregated albumin SPET. By contrast to the homogeneous MIBG uptake in the lungs of the healthy subjects, MIBG uptake was folcally decreased in correspondence with the ILAs in all patients, including 11 patients (73.3%) of group A with relatively preserved lung perfusion. The reduction MIBG uptake was significant (P<0.0001), and the MIBG clearance rate from the ILAs was also significantly faster than the clearance rates from the normal lungs and contralateral non-ILAs (both P<0.01). Group B patients showed significantly lower MIBG uptake and faster clearance from the ILAs than group A patients (P<0. 001 and P<0.05, respectively), although there was no significant difference in the clearance from the non-ILAs. Overall, MIBG uptake/clearance from the ILAs correlated significantly with the radiation dose in the 31 patients (r = -0.656; P<0.0001 and r = 0. 387; P<0.05, respectively). Perfusion changes were inversely correlated with the clearance from the ILAs (r = -0.432, P<0.05), but did not correlate with MIBG uptake. These preliminary results suggest that MIBG may have the potential to be a marker of abnormal functional status of the PNS produced by irradiation and may facilitate investigation of irradiation lung injury independently of morphological or lung perfusion changes.     

Study on the decay of iodine-123

Following the decay of a sample of ¹²³I, it was found after about two weeks the decay no longer corresponds to a half life of 13.21 h, but to a longer half life equal to that of ^123mTe.After a chemical separation of iodine/tellurium, and comparing the measured activities with a reference solution, the branching ratio of ¹²³I/^123mTe was found to be (7.7 ± 0.2) 10⁻⁵.     

Dosimetry of iodine-123 iomazenil in humans

The distribution of the central benzodiazepine receptor specific ligand iodine-123 iomazenil was investigated in seven human adults from whole-body scans, blood samples and urine collected up to 24 h after injection. Using 12 source organs, the MIRD method was applied to calculate the absorbed radiation dose of the radioligand in various organs. The urinary bladder wall (0.15 mGy/MBq), lower large intestinal wall (0.071 mGy/MBq) testes (0.044 mGy/MBq) and upper large intestined wall (0.038 mGy/MBq) received the highest absorbed doses. The average effective dose equivalent of ¹²³I-IBZM for adults was estimated to be 0.033 mSv/MBq.     

Superiority of iodine-123 compared with iodine-131 scanning for thyroid remnants in patients with differentiated thyroid cancer

PURPOSE: Iodine-123 is a pure gamma emitter and has excellent characteristics for imaging with modern scintillation cameras. The goal of this study was to compare the performance of I-123 and I-131 as imaging agents for whole-body scanning in patients with differentiated thyroid cancer undergoing ablation for thyroid remnants after initial surgery. METHODS: Fourteen patients with differentiated thyroid cancer who had undergone near-total thyroidectomy and had serum thyroid-stimulating hormone levels greater than 40 mU/I underwent diagnostic scanning 5 hours after administration of 48 to 56 MBq (1.3 to 1.5 mCi) I-123 and 48 hours after administration of 111 MBq (3 mCi) I-131. After receiving ablative I-131 therapy, they also underwent whole-body planar imaging 7 days later. The diagnostic I-123 and I-131 scans were compared with each other and with the post-therapy images by two nuclear medicine physicians and one endocrinologist. RESULTS: The diagnostic scans revealed 35 foci in the thyroid bed and neck. The I-123 images showed all 35 foci, but only 32 of the 35 foci (91 %) were seen on the I-131 scans. The findings of pre- and post-therapy scans were concordant in 11 of 13 patients, and the same general sites of uptake (left and right thyroid bed, midline) were revealed on both sets of images. In one patient, a focus seen on the diagnostic I-123 and I-131 images was not visualized on the post-therapy scan and was thought to represent possible stunning. An additional area of uptake in the lower right neck and upper mediastinum was present on the post-therapy scan of another patient, but it was not seen on diagnostic images. CONCLUSION: These results show improved quality of imaging with 50 MBq (1.5 mCi) I-123 compared with 111 MBq (3 mCi) I-131 for whole-body scanning in patients with differentiated thyroid cancer undergoing thyroid remnant ablation. I-123 imaging may prove to be the preferred procedure in such settings in patients with differentiated thyroid cancer.     

Increased cardiac sympathetic activity in patients with hypothyroidism as determined by iodine-123 metaiodobenzylguanidine scintigraphy

Clinical manifestations of hypothyroidism, such as bradycardia, suggest decreased sympathetic tone. However, previous studies in patients with hypothyroidism have suggested that increased plasma noradrenaline (NA) levels represent enhanced general sympathetic activity. As yet, cardiac sympathetic activity (CSA) in hypothyroidism has not been clarified. To evaluate CSA in patients with hypothyroidism, iodine-123 metaiodobenzylguanidine (MIBG) scintigraphy was performed in eight patients with hypothyroidism before therapy and in ten normal control patients. Planar images were obtained at 15 min and 4 h after injection of MIBG. The ratio of early myocardial uptake to the total injected dose (MU) and myocardial clearance of MIBG within 4 h p.i. (MC) were calculated. Plasma NA was also measured, and echocardiography was performed in all patients. Those patients with hypothyroidism in the euthyroid state after medical therapy were also evaluated in a similar manner. Left ventricular ejection fraction, measured by echocardiography, did not differ significantly between the groups. NA, MU and MC were significantly higher in patients with hypothyroidism than in controls, and all parameters were decreased after therapy. MC was well correlated with NA in hypothyroidism (r=0.86) before therapy. We conclude that CSA is increased in patients with hypothyroidism, in parallel with the enhanced general sympathetic activity.     

The development of new method for the assessment of perfusion reserve using split dose iodine-123-IMP SPECT: one-day protocol by modified ARG method

Evaluation of the regional cerebrovascular reactivity (rCVR) to a cerebral vasodilatory stimulus is important in the investigation of patients with ischemic cerebrovascular disease. We devised a simplified one-day protocol technique using [123I]N-isopropyl-p-iodoamphetamine (IMP) autoradiography (ARG) with SPECT. To validate the accuracy of IMP-ARG for quantifying rCVR to acetazolamide, we compared rCVR measured using IMP-ARG with rCVR calculated using IMP split dose method of microsphere model. Twenty patients with chronic steno-occlusive disease in a unilateral major cerebral artery underwent 123I-SPECT. On rCBF SPECT image above 3.5 cm from OM line, large cortical regions of interest (ROI) was bilaterally determined for bilateral middle cerebral artery and anterior cerebral artery. Based on rCBF values in each ROI, rCVR to acetazolamide was calculated. Significant correlation was observed between rCVR values obtained using IMP-ARG and microsphere model IMP methods in the 80 ROIs examined in the 20 patients (r = 0.72; p < 0.001). The result demonstrated that [123I]IMP-ARG split dose method can quantify rCVR non-invasively in a short time.     

A comparative study of simple methods to quantify cerebral blood flow with acetazolamide challenge by using iodine-123-IMP SPECT with one-point arterial sampling

The aim of this study was to compare the accuracy of simplified methods for quantifying rCBF with acetazolamide challenge by using 123I-N-isopropyl-p-iodoamphetamine (IMP) and SPECT with one-point arterial sampling. After acetazolamide administration we quantified rCBF in 12 subjects by the following three methods: (a) the modified microsphere method, (b) the IMP-autoradiographic (ARG) method based on a two-compartment one-parameter model, and (c) the simplified method based on a two-compartment two-parameter model (functional IMP method). The accuracy of these methods was validated by comparing rCBF values with those obtained by the standard method: the super-early microsphere method with continuous withdrawal of arterial blood. On analyzing rCBF in each flow range (0-0.25, 0.25-0.5, 0.5-0.75 and more than 0.75 ml/g/min), rCBF values obtained by both methods (a) and (c) showed significant correlations (p < 0.01) with those obtained by the standard method in every range, but rCBF values obtained by method (b) did not significantly correlated in the high flow range (0.5-0.75 and more than 0.75 ml/g/min). Method (c) was found to be the most accurate, even though it needs two serial SPECT scans. When requiring one SPECT scan, method (a) was considered to be superior to method (b) because of its accuracy, especially in high flow regions loaded with acetazolamide.     

Prolonged lung retention of 123I-IMP in pulmonary disease

The accumulation of venously injected ¹²³I-IMP in the lung was studied. Between 30 and 50 min after the injection of the 1.5 mCi ¹²³I-IMP, the concentration of ¹²³I-IMP in the broncho-alveolar lavage fluid were much higher than in the blood. It was considered that ¹²³I-IMP was transported into the alveolar spaces and was absorbed by the alveolar cells. The half time (T _1/2) of the ¹²³I-IMP release from the lung between 10 and 25 min immediately after the injection was calculated. In normal subjects the T _1/2 ranged between 25 and 44 min and was prolonged in subjects with pulmonary fibrosis, sarcoidosis, and allergic alveolitis. It was considered that the retention of ¹²³I-IMP was related not only to the endothelial cells, but also to the alveolar cells. It was considered that the analysis of the lung release of ¹²³I-IMP forms a new lung dysfunction index.     

Prolonged lung retention of123I-IMP in pulmonary fibrosis

We compared radiographic findings and the retention of N-isopropyl- p[123I]-iodoamphetamine (123I-IMP) in 23 patients with pulmonary fibrosis. During the 30 minutes following a rapid injection of 55.5 MBq of 123I-IMP into the antecubital vein, the image of regional activity was stored. After this, 185 MBq of 99mTc-MAA was injected and its image was stored to determine the region of interest. The half time (T1/2) of 123I-IMP release from the lung was calculated in each pixel between 10 and 25 minutes after the injection. Chest roentgenograms were taken, and the lung field was divided into 6 portions (right upper, middle and lower, and left upper, middle and lower). A quantitative score was assigned to the radiographic finding (X-ray score). The T1/2 values in the above patients were longer than the T1/2 values in normal subjects. Prolonged T1/2 values were observed in the lung fields which had high X-ray scores. The X-ray scores and the T1/2 values in corresponding areas had a positive relation.     

Prolonged lung retention of 123I-IMP in pulmonary disease

The accumulation of venously injected 123I-IMP in the lung was studied. Between 30 and 50 min after the injection of the 1.5 mCi 123I-IMP, the concentration of 123I-IMP in the broncho-alveolar lavage fluid were much higher than in the blood. It was considered that 123I-IMP was transported into the alveolar spaces and was absorbed by the alveolar cells. The half time (T1/2) of the 123I-IMP release from the lung between 10 and 25 min immediately after the injection was calculated. In normal subjects the T1/2 ranged between 25 and 44 min and was prolonged in subjects with pulmonary fibrosis, sarcoidosis, and allergic alveolitis. It was considered that the retention of 123I-IMP was related not only to the endothelial cells, but also to the alveolar cells. It was considered that the analysis of the lung release of 123I-IMP forms a new lung dysfunction index.     

Relationship between peripheral lung cancer and the surrounding bronchi, pulmonary arteries, pulmonary veins: a multidetector CT observation

Aim

This study aimed to investigate the relationship between peripheral lung cancer and the surrounding pulmonary vessels and bronchi using contrast-enhanced multidetector computed tomography (MDCT) and to analyze associated factors such as pathology types, stage, size, density, and location of peripheral lung cancer.

Materials and Methods

A total of 93 patients with solitary peripheral lung cancers underwent contrast-enhanced MDCT before thoracotomy were enrolled. Multiplanar reconstruction, maximal intensity projection, and volume rendering were used for demonstrating the patterns of the tumor-bronchi (Br), tumor-pulmonary artery (PA) and tumor-pulmonary vein (PV) relationship, respectively. Five subtypes were identified: Type1 (Br1, PA1 and PV1), Br, PA, or PV was erupted at the edge of nodule; Type2 (Br2, PA2, and PV2), erupted at the center of nodule; Type3 (Br3, PA3 and PV3), penetrated through the nodule; Type4, (Br4, PA4 and PV4), contacting the nodule but stretched or encased; Type5 (Br5, PA5, and PV5), contacting the nodule but smoothly compressed.

Results

Both bronchi and PA were interrupted in 70 (Type 1+2); both narrowed in 9 (Type 3+4). The bronchi and PA changes surrounding the lung cancer had positive relations (χ²=12.3918, r=0.7524, P<.01). Br1 and PA1 were more often seen in the group of solid, ≥2.0 cm, and Stage II-IV focal lesions, while Br2 and PA2, more often in the group of part-solid, non-solid, <2.0 cm, and Stage I focal lesions. PV2 was more often seen in the part-solid and non-solid focal lesions group, while PV (4+5), more often in solid focal lesions group.

Conclusion

MDCT can demonstrate and subtype relationships among peripheral lung cancer and the bronchi, pulmonary arteries and pulmonary veins. This can be the basis for further clinical research and differential diagnosis.     

Dosimetry of iodine-123 iodobenzamide in healthy volunteers

The distribution of the dopamine D₂-receptor specific ligand iodine-123 (S)-(–)-2-hydroxy-3-iodo-6-methoxy-N[(1-ethyl-2-pyrrolidinyl)methyl]-benzamide (1231-IBZM) was investigated in human adults from whole-body scans, blood samples and urine collected up to 48 h after injection. Results from the present study performed in six healthy volunteers were combined with those of five volunteers from a previous study. Using the brain, liver, lungs and spleen as source organs, the MIRD method was applied to calculate the absorbed radiation dose of the radioligand in various organs. The thyroid (despite blockage), gall-bladder wall, large intestinal walls and spleen received the highest absorbed doses. The average effective dose equivalent of ¹²³I-IBZM for adults was estimated to be 0.034 mSv/MBq. The absorbed dose to the thyroid may be a limiting factor for 1231-IBZM studies in children.