<Superscript>131</Superscript>I-MIBG Therapy in metastatic phaeochromocytoma and paraganglioma

Purpose ¹³¹Iodine metaiodobenzylguanidine (¹³¹I-MIBG) is a radiopharmaceutical used for scintigraphic localisation of phaeochromocytomas and paragangliomas. The experience with its therapeutic use is limited. We report our experience for the treatment of malignant phaeochromocytoma and paraganglioma. Materials and methods The charts of 19 patients with malignant phaeochromocytoma (n = 12) or paraganglioma (n = 7), who were treated with ¹³¹I-MIBG, were retrospectively reviewed. Four patients (21%) received radiotherapy, three (16%) chemotherapy, and in one patient (5%), both chemotherapy and radiotherapy was given before ¹³¹I-MIBG therapy. Response to ¹³¹I-MIBG treatment was evaluated by objective as tumour response, biochemical and subjective response. Results Of the 19 patients, 13 (68%) were men, 6 (32%) were women. Ages ranged from 22 to 68 years (median, 47). The median initial dose was 7.4 GBq (200 mCi; range, 6.7 GBq–25.9 GBq, 180–700 mCi); median cumulative dose was 22.2 GBq (600 mCi; range, 6.8 GBq–81.4 GBq, 183–2200 mCi). Objective tumour response was achieved in 47% of the patients. Biochemical response rate was 67%, and symptomatic response was seen in 89% of the patients. Overall median follow-up was 29 months, with a range of 3–93 months. Haematologic complications were the most common side effects and were observed in 26% of the patients. Conclusion Our data support that symptomatic and biochemical response can be reached with ¹³¹I-MIBG therapy in patients with metastatic phaeochromocytoma and paraganglioma. Although complete tumour response was not observed, the palliation and control of tumour function by ¹³¹I-MIBG therapy may be valuable for the patients.     

The absorbed dose to the blood is a better predictor of ablation success than the administered <Superscript>131</Superscript>I activity in thyroid cancer patients

Purpose  

The residence time of ¹³¹I in the blood is likely to be a measure of the amount of ¹³¹I that is available for uptake by thyroid remnant tissue and thus the radiation absorbed dose to the target tissue in ¹³¹I ablation of patients with differentiated thyroid cancer (DTC). This hypothesis was tested in an investigation on the dependence of the success rate of radioiodine remnant ablation on the radiation absorbed dose to the blood (BD) as a surrogate for the amount of ¹³¹I available for iodine-avid tissue uptake.     

Radioembolisation with <Superscript>90</Superscript>Y-microspheres: dosimetric and radiobiological investigation for multi-cycle treatment

Introduction  Radioembolisation with ⁹⁰Y-microspheres is a new locoregional treatment of hepatic lesions, usually applied as single cycle. Multi-cycle treatments might be considered as a strategy to improve the risk-benefit balance. With the aim to derive suitable information for patient tailored therapy, available patients’ dosimetric data were reviewed according to the linear–quadratic model and converted into biological effective dose (BED) values. Single vs. multi-cycle approaches were compared through radiobiological perspective. Materials and methods  Twenty patients with metastatic lesions underwent radioembolisation. The ⁹⁰Y-administered activity (AA) was established in order to respect a precautionary limit dose (40 Gy) for the non-tumoral liver (NTL). BED was calculated setting α/β = 2.5 Gy (NTL), 10 Gy (tumours); T _1/2,eff = T _1/2,phys = 64.2 h; T _1/2,rep = 2.5 h (NTL), 1.5 h (tumours). The BED to NTL was considered as a constraint for multi-cycle approach. The AA for two cycles and the percent variations of AA, tumour dose, BED were estimated. Results  In one-cycle, for a prescribed BED to NTL of 64 Gy (NTL dose = 40 Gy), AA was 1.7 (0.9–3.2) GBq, tumour dose was 130 (65–235) Gy, and tumour BED was 170 (75–360) Gy. Considering two cycles, ∼15% increase was found for AA and dose to NTL, with unvaried BED for NTL. Tumour dose increase was 20 (10–35) Gy; tumour BED increase was 10 (3–11) Gy. In different protocols allowing 80 Gy to NTL, the BED sparing estimated was ∼50 Gy (two cycles) and 65 Gy (three cycles). Conclusions  From a radiobiological perspective, multi-cycle treatments would allow administering higher activities with increased tumour irradiation and preserved radiation effects on NTL. Trials comparing single vs. multiple cycles are suggested.     

Visualization of nasolacrimal drainage system after radioiodine therapy in patients with thyroid cancer

The objective of this study was to report three cases with an accumulation of ¹³¹I in the nasolacrimal duct after radioiodine therapy for papillary thyroid cancer. A whole-body scan was taken 3 days after the administration of 3.7 GBq of ¹³¹I. Single-photon emission computed tomography (SPECT)/CT images were added when the location of a focal tracer uptake was undetermined on whole-body scans. In case 1, a 62-year-old woman complained of epiphora of the left eye after nine radioiodine therapies with a cumulative dose of 31.08 GBq. The left nasolacrimal duct was visualized at her tenth treatment with ¹³¹I. In case 2, a series of three radioiodine therapies had been given to a 73-year-old woman with a cumulative dose of 11.1 GBq. The accumulation of ¹³¹I was noted in the left nasolacrimal duct at her fourth treatment. She complained of epiphora of the left eye. In case 3, bilateral nasolacrimal ducts were visualized at the second radioiodine therapy in a 75-year-old woman. The patient had received 3.7 GBq of ¹³¹I at the first therapy. She did not complain of epiphora. It is possible that radiation from ¹³¹I that is secreted in tears and/or actively accumulated in the nasolacrimal duct may induce nasolacrimal duct obstruction. ¹³¹I in tears would be responsible for the visualization of nasolacrimal duct in the first two cases. ¹³¹I actively accumulated in the nasolacrimal duct might have been visualized in the third case. In summary, ¹³¹I is excreted in tears and is actively accumulated in the nasolacrimal duct. Obstruction of the lacrimal drainage system could occur after high-dose radioiodine therapy.     

非高危分化型甲状腺癌低剂量和高剂量131I清甲疗效的分析

目的 研究应用低剂量（1.11 GBq）和高剂量（3.70 GBq）放射性131I清除非高危分化型甲状腺癌（DTC）术后残留甲状腺组织的疗效。 方法 回顾性分析行131I清甲治疗的63例非高危DTC患者的临床资料,采用Binary Logistic回归分析年龄、首次手术距清甲的时间间隔、甲状腺24 h摄碘率、血清TSH水平和清甲剂量对清甲疗效的影响;27例患者给予低剂量、36例患者给予高剂量的131I清甲治疗,采用Pearsonχ2检验分析低剂量和高剂量131I清甲疗效的差异,P < 0.05表示差异有统计学意义。 结果 63例非高危DTC患者中,清甲成功者46例（73.02%,46/63）、未成功者17例（26.98%,17/63）;Binary Logistic回归分析显示,131I清甲剂量是清甲成功与否的主要影响因素（Wald=6.42,P=0.011）;27例给予低剂量131I清甲患者中有15例清甲成功,36例给予高剂量131I清甲者中31例清甲成功,Pearsonχ2检验结果表明,高剂量131I清甲成功率（86.11%,31/36）明显高于低剂量（55.56%,15/27）（χ2=7.311,P=0.007）。 结论 在临床实践中,当残余甲状腺组织较少时,对于非高危DTC患者可考虑采用高剂量131I清甲治疗,提高一次清甲成功率。     

<Superscript>11</Superscript>C-methionine (MET) and <Superscript>18</Superscript>F-fluorothymidine (FLT) PET in patients with newly diagnosed glioma

Purpose  The purpose of this prospective study was to clarify the individual and combined role of l-methyl-¹¹C-methionine-positron emission tomography (MET-PET) and 3′-deoxy-3′-[¹⁸F]fluorothymidine (FLT)-PET in tumor detection, noninvasive grading, and assessment of the cellular proliferation rate in newly diagnosed histologically verified gliomas of different grades. Materials and methods  Forty-one patients with newly diagnosed gliomas were investigated with MET-PET before surgery. Eighteen patients were also examined with FLT-PET. MET and FLT uptakes were assessed by standardized uptake value of the tumor showing the maximum uptake (SUV_max), and the ratio to uptake in the normal brain parenchyma (T/N ratio). All tumors were graded by the WHO grading system using surgical specimens, and the proliferation activity of the tumors were determined by measuring the Ki-67 index obtained by immunohistochemical staining. Results  On semiquantitative analysis, MET exhibited a slightly higher sensitivity (87.8%) in tumor detection than FLT (83.3%), and both tracers were 100% sensitive for malignant gliomas. Low-grade gliomas that were false negative on MET-PET also were false negative on FLT-PET. Although the difference of MET SUV_max and T/N ratio between grades II and IV gliomas was statistically significant (P < 0.001), there was a significant overlap of MET uptake in the tumors. The difference of MET SUV_max and T/N ratio between grades II and III gliomas was not statistically significant. Low-grade gliomas with oligodendroglial components had relatively high MET uptake. The difference of FLT SUV_max and T/N ratio between grades III and IV gliomas was statistically significant (P < 0.01). Again, the difference of FLT SUV_max and T/N ratio between grades II and III gliomas was not statistically significant. Grade III gliomas with non-contrast enhancement on MR images had very low FLT uptake. In 18 patients who underwent PET examination with both tracers, a significant but relatively weak correlation was observed between the individual SUV_max of MET and FLT (r = 0.54, P < 0.05) and T/N ratio of MET and FLT (r = 0.56, P < 0.05). Total FLT uptake in the tumor had a higher correlation (r = 0.89, P < 0.001) with Ki-67 proliferation index than MET uptake (r = 0.49, P < 0.01). Conclusions  PET studies using MET and FLT are useful for tumor detection in newly diagnosed gliomas. However, there is no complimentary information in tumor detection with simultaneous measurements of MET- and FLT-PET in low grade gliomas. FLT-PET seems to be superior than MET-PET in noninvasive tumor grading and assessment of proliferation activity in gliomas of different grades.     

Studying neonatal bilirubin encephalopathy with conventional MRI,MRS, and DWI

Introduction  The purpose of this study was to evaluate the diagnostic value of conventional magnetic resonance imaging (MRI), proton magnetic resonance spectroscopy (¹H-MRS), and diffusion-weighted imaging (DWI) for neonatal bilirubin encephalopathy. Methods  We collected conventional MRI in 24 neonates with neonatal bilirubin encephalopathy. We performed ¹H-MRS and DWI sequences to nine of the 24 patients and seven age-matched healthy control subjects. Multiple-voxel ¹H-MRS data were acquired using PRESS pulse sequence with TE = 135 ms and TR = 1500 ms. The spectroscopic regions of interest were the bilateral basal ganglia and thalamus with a 1.0 mL spatial resolution. The data from DWI were collected by using a single shot-spin echo-echo planar imaging sequence with TR/TE: 2900/98, and imaging regions were also focused on the bilateral basal ganglia and thalamus. Results  Nineteen of the 24 patients had abnormal T₁-weighted image hyperintensity in the globus pallidus, but these lesions appeared as normal T₂-weighted image intensity in the same region. Ten of the 24 patients had T₁-weighted image high signal intensity in the subthalamic nucleus and appeared as normal intensity in the region for the T₂-weighted images. The peak area ratios of NAA/Cho and NAA/Cr were significantly decreased (t-test, P < 0.05) in the patients compared to the controls in the basal ganglia. Conclusion  Conventional MR imaging and ¹H-MRS are important complementary tools in the diagnosis of neonatal bilirubin encephalopathy. The study provides important information for applying these MR modalities to evaluate neonates with bilirubin encephalopathy.     

Combined metabolic and morphologic imaging in thyroid carcinoma patients with elevated serum thyroglobulin and negative cervical ultrasonography: role of <Superscript>124</Superscript>I-PET/CT and FDG-PET

Purpose This study sought to compare iodine-124 positron emission tomography/computed tomography (¹²⁴I-PET/CT) and 2-[¹⁸F]fluoro-2-deoxy-d-glucose- (FDG-) PET in the detection of recurrent differentiated thyroid carcinoma (DTC) lesions in patients with increasing serum thyroglobulin (Tg), Tg-antibodies, or both, but without pathological cervical ultrasonography. We assessed the lesion detection accuracy of ¹²⁴I-PET alone, CT alone, ¹²⁴I-PET/CT, FDG-PET, and all these modalities combined. Material and methods The study included 21 patients (9 follicular, 12 papillary DTC) who had been rendered disease-free by thyroidectomy and radioiodine treatment (RIT) and followed up for 21–275 months after the last RIT. In all patients, FDG-PET was performed first. Within 1 week, ¹²⁴I-PET/CT was performed 24 h after oral administration of 43 ± 11 MBq ¹²⁴I. Imaging results were correlated with further clinical follow-up with (n = 12) or without (n = 9) post-study histology as the reference standard. Results The sensitivities for DTC lesion detection were: ¹²⁴I-PET, 49%; CT, 67%; ¹²⁴I-PET/CT, 80%; FDG-PET, 70%; and all modalities combined, 91%. For local recurrences (distant metastases), the sensitivities were: ¹²⁴I-PET, 60% (45%); CT, 20% (84%); and FDG-PET, 65% (71%). One-third of lesions demonstrated pathological tracer uptake with both ¹²⁴I- and FDG-PET, while two-thirds were positive with only one of these modalities. Conclusion Used together, ¹²⁴I-PET and CT allow localization of foci of highly specific ¹²⁴I uptake as well as non-iodine-avid lesions. The combination of ¹²⁴I-PET/CT and FDG-PET improves restaging in recurrent DTC by enabling detection on whole-body scans of local recurrence or metastases that are often not found if only one of the methods or other imaging modalities are applied.     

Disseminated iodine-avid lung metastases in differentiated thyroid cancer: a challenge to 124I PET

Aim This study assessed the ability of visual and quantitative 124-iodine positron emission tomography (¹²⁴I PET) data to detect disseminated iodine-avid lung metastases (DILM) of differentiated thyroid cancer (DTC). Materials and methods Using “post-therapy” 131-iodine (¹³¹I) whole-body scintigraphy (TxWBS) and thoracic computed tomography (CT), we retrospectively divided 70 consecutive DTC patients undergoing ¹²⁴I PET dosimetry ∼1 week before ¹³¹I therapy into subgroups positive (n = 7) or negative (n = 63) for DILM, defined as lung metastases visible on TxWBS but not thoracic CT. To determine whether ¹²⁴I PET data could distinguish patients with versus without DILM, we compared these data with the TxWBS findings. The ¹²⁴I PET data were acquired via whole-body PET scans ∼24 h after oral administration of ¹²⁴I, 24 ± 2 MBq. Quantitative data comprised absolute lung ¹²⁴I activity concentrations and lung-to-background (L/B) ¹²⁴I uptake ratios. Results Only 1/7 DILM-positive patients had visible disseminated lung uptake. Absolute ¹²⁴I lung uptake activities overlapped considerably between both groups and did not differ significantly (P = 0.150). Mean L/B ratios, however, differed significantly between the DILM-positive and negative groups (P < 0.001). Nevertheless, L/B ratios overlapped between the groups (0.62–1.37 versus 0.13–0.69). Conclusion Quantitative analysis of ¹²⁴I PET data using the L/B ratio is a promising tool to detect patients suspicious for DILM. However, L/B ratios overlapped between the groups to an extent that an unequivocal diagnosis based solely on this criterion was impossible in some patients. In those cases, additional diagnostic tests are necessary for diagnosis.     

Airway complication occurring during radioiodine treatment for Graves' disease

Airway complications rarely occur in ¹³¹I radioiodine therapy for Graves' disease. This study presents two cases in which ¹³¹I therapy caused this acute complication. The patients complained of the symptom 6 h and 33 h after administration of ¹³¹I. A histamine H1 receptor antagonist and hydrocortisone rapidly resolved symptoms in both cases. These two cases remind physicians that ¹³¹I therapy for Graves' disease may cause potentially life-threatening complications.     

Guidelines for radioiodine therapy of differentiated thyroid cancer

Introduction  The purpose of the present guidelines on the radioiodine therapy (RAIT) of differentiated thyroid cancer (DTC) formulated by the European Association of Nuclear Medicine (EANM) Therapy Committee is to provide advice to nuclear medicine clinicians and other members of the DTC-treating community on how to ablate thyroid remnant or treat inoperable advanced DTC or both employing large 131-iodine (¹³¹I) activities. Discussion  For this purpose, recommendations have been formulated based on recent literature and expert opinion regarding the rationale, indications and contraindications for these procedures, as well as the radioiodine activities and the administration and patient preparation techniques to be used. Recommendations also are provided on pre-RAIT history and examinations, patient counselling and precautions that should be associated with ¹³¹I iodine ablation and treatment. Furthermore, potential side effects of radioiodine therapy and alternate or additional treatments to this modality are reviewed. Appendices furnish information on dosimetry and post-therapy scintigraphy.     

Clinical correlation of the binding potential with <Superscript>123</Superscript>I-FP-CIT in de novo idiopathic Parkinson’s disease patients

Purpose  The aim of this study was to evaluate the accuracy of different single-photon emission computed tomography (SPECT) reconstruction techniques in measuring striatal N-ω-fluoropropyl-2β-carbomethoxy-3β-4-[¹²³I]iodophenyl-nortropane (¹²³I-FP-CIT) binding in de novo Parkinson’s disease (PD) patients, in order to find a correlation with clinical scales of disease severity in the initial phases of disease. Methods  Thirty-six de novo PD patients underwent ¹²³I-FP-CIT SPECT and MRI scan. SPECT data were reconstructed with filtered back projection (FBP), with an iterative algorithm (ordered subset expected maximization, OSEM) and with a method previously developed in our institution, called least-squares (LS) method. The ratio of specific to non-specific striatal ¹²³I-FP-CIT binding (binding potential, BP) was used as the outcome measure with all the reconstruction methods (BP_FBP, BP_OSEM, BP_LS). Results  The range of values of striatal BP_LS was significantly greater than BP_FBP and BP_OSEM. For all striatal regions, estimates of BP_FBP correlated well with BP_OSEM (r = 0.84) and with BP_LS (r = 0.64); BP_OSEM correlated significantly with BP_LS (r = 0.76). A good correlation was found between putaminal BP_LS and Hoen and Yahr, Unified PD Rating Scale (UPDRS) and lateralized UPDRS motor scores (r = −0.46, r = −0.42, r = −0.39, respectively). Neither putaminal BP_FBP nor putaminal BP_OSEM correlated with any of these motor scores. Conclusions  In de novo PD patients, ¹²³I-FP-CIT BP values derived from FBP and OSEM reconstruction techniques do not permit to differentiate PD severity. The LS method instead finds a correlation between striatal BP and disease severity scores. The results of this study support the use of ¹²³I-FP-CIT BP values estimated with the LS method as a biomarker of PD severity.     

分化型甲状腺癌术后首次131I清甲效果影响因素的分析

目的 探讨分化型甲状腺癌（DTC）患者术后首次行131I清甲治疗疗效的影响因素。 方法 回顾性分析2013年4月至2022年3月于河北医科大学第四医院行DTC全切或近全切术后首次行131I 治疗的159例患者的临床资料,其中男性51例、女性108例,年龄24~78（46.5±11.9）岁。将患者按首次行131I治疗的剂量（2.96 GBq、3.70 GBq和5.55~7.40 GBq）分为3组进行研究。按清甲成功的判断标准,即131I 治疗后（4±1）个月131I诊断性全身显像示甲状腺床无放射性浓聚,分析患者的性别、年龄、手术方式、131I治疗前血清甲状腺球蛋白（Tg）水平及促甲状腺激素（TSH）水平、131I治疗距离手术的时间、131I治疗剂量对清甲效果的影响。计数资料的组间比较采用χ2检验。 结果 159例DTC患者首次行131I清甲的成功率为70.4%（112/159）。2.96 GBq组的首次131I清甲成功率为58.3%（21/36）,3.70 GBq组为69.2%（63/91）,5.55~7.40 GBq组为87.5%（28/32）,3组间的差异有统计学意义(χ2=7.071,P<0.05) 。手术方式为全切的DTC患者的清甲成功率为74.2%（95/128）,高于近全切患者的54.8%（17/31）,且差异有统计学意义（χ2=4.502,P<0.05）。治疗前TSH水平≥30 mU/L患者清甲成功率为73.9%（99/134）,高于治疗前TSH水平<30 mU/L患者的52.0%（13/25）,且差异有统计学意义（χ2=4.844,P<0.05）。患者在性别、年龄、131I治疗前血清Tg水平以及131I治疗距离手术的时间之间的差异均无统计学意义（χ2=0.311~3.073,均P>0.05）。 结论 131I治疗剂量、手术方式、131I治疗前TSH水平是影响DTC全切或近全切患者清甲成功率的因素。     

Pregnancy after high therapeutic doses of iodine-131 in differentiated thyroid cancer: potential risks and recommendations

Seventy female patients who had been treated with high doses of iodine-131 for differentiated thyroid cancer (DTC) and who had a subsequent pregnancy were evaluated. The total ¹³¹I dose ranged from 1.85 to 16.55 GBq (mean±SD=4.39±25.20 GBq). Age at first therapy ranged from 15 to 36 years (mean±SD = 24.3±5.0 years) and the interval from ¹³¹I therapy topregnancy varied from 2to 10 years (mean±SD = 5.3±2.8 years). The estimated radiation doseto the gonads ranged from 10 to 63 cGy (mean±SD = 24.0±13.5 eGy). All patients were treated with l-thyroxine at doses capable of suppressing thyroid-stimulating hormone. Seventy-three children were followed-up and seven pregnancies are still in progress. One child was affected by Fallot's trilogy and three had a low birth weight though with subsequent normal growth; the others were healthy with subsequent normal growth. No newborn with clinical or biochemical thyroid dysfunctions was found. Two spontaneous abortions during the second month of pregnancy were recorded. One of two patients in question subsequently had two healthy children. On the basis of these data, previous administration of high ¹³¹I doses does not appear to be a valid reason for dissuading young female DTC patients from considering pregnancy. However, patients should be advised to avoid pregnancy after ¹³¹I administration for a period sufficient to ensure complete elimination of the radionuclide and to permit confirmation of complete disease remission, i.e. at least 1 year in our opinion.     

Assessment of 18F-labeled mitochondrial complex I inhibitors as PET myocardial perfusion imaging agents in rats, rabbits, and primates

Purpose  Myocardial extractions of mitochondria complex I (MC-I) inhibitors were high and well correlated with flow. This study assessed the potential of MC-I inhibitors to be developed as myocardial perfusion imaging (MPI) agents. Methods  RP1003, RP1004, and RP1005 representing three classes of MC-I inhibitor were synthesized and radio-labeled with ¹⁸F. These agents were evaluated for IC₅₀ values, tissue biodistribution, and cardiac PET imaging. ¹⁸F-RP1004 was further examined for first-pass extraction and by imaging in non-human primates (NHP) and rats following coronary ligation. Results  RP1003, RP1004, and RP1005 exhibited high MC-I inhibitory activity with IC₅₀ of 3.7, 16.7, and 14.4 nM. Heart uptakes in rats (percent injected dose per gram tissue) at 15 and 60 min after injection were 3.52 ± 0.36 and 2.68 ± 0.20 for ¹⁸F-RP1003, 2.40 ± 0.21 and 2.67 ± 0.27 for ¹⁸F-RP1004, and 2.28 ± 0.12 and 1.81 ± 0.17 for ¹⁸F-RP1005. The heart to lung and liver uptake ratios were favorable for cardiac imaging with these agents. In isolated perfused rabbit hearts, the uptake of ¹⁸F-RP1004 increased from 0.74 ± 0.19 to 1.68 ± 0.39 mL/min/g at flow rates of 1.66 to 5.06 mL/min/g. These values were higher than or similar to that of ^99mTc-sestamibi. Cardiac imaging with these agents in rats and rabbits allowed visualization of the heart with minimal lung interference and rapid liver activity clearance. Imaging with ¹⁸F-RP1004 also showed clear myocardium and marked liver activity washout in the NHP and clear detection of the perfusion-deficit area associated with left coronary artery ligation in the rat. Conclusion  MC-I inhibitors have the potential to be a new class of MPI agent.     

Targeting murine heart and brain: visualisation conditions for multi-pinhole SPECT with <Superscript>99m</Superscript>Tc- and <Superscript>123</Superscript>I-labelled probes

Purpose  The study serves to optimise conditions for multi-pinhole SPECT small animal imaging of ¹²³I- and ^99mTc-labelled radiopharmaceuticals with different distributions in murine heart and brain and to investigate detection and dose range thresholds for verification of differences in tracer uptake. Methods  A Triad 88/Trionix system with three 6-pinhole collimators was used for investigation of dose requirements for imaging of the dopamine D₂ receptor ligand [¹²³I]IBZM and the cerebral perfusion tracer [^99mTc]HMPAO (1.2–0.4 MBq/g body weight) in healthy mice. The fatty acid [¹²³I]IPPA (0.94 ± 0.05 MBq/g body weight) and the perfusion tracer [^99mTc]sestamibi (3.8 ± 0.45 MBq/g body weight) were applied to cardiomyopathic mice overexpressing the prostaglandin EP₃ receptor. Results  In vivo imaging and in vitro data revealed 45 kBq total cerebral uptake and 201 kBq cardiac uptake as thresholds for visualisation of striatal [¹²³I]IBZM and of cardiac [^99mTc]sestamibi using 100 and 150 s acquisition time, respectively. Alterations of maximal cerebral uptake of [¹²³I]IBZM by >20% (116 kBq) were verified with the prerequisite of 50% striatal of total uptake. The labelling with [^99mTc]sestamibi revealed a 30% lower uptake in cardiomyopathic hearts compared to wild types. [¹²³I]IPPA uptake could be visualised at activity doses of 0.8 MBq/g body weight. Conclusion  Multi-pinhole SPECT enables detection of alterations of the cerebral uptake of ¹²³I- and ^99mTc-labelled tracers in an appropriate dose range in murine models targeting physiological processes in brain and heart. The thresholds of detection for differences in the tracer uptake determined under the conditions of our experiments well reflect distinctions in molar activity and uptake characteristics of the tracers. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Selective hepatic arterial infusion of In-111-DTPA-Phe<Superscript>1</Superscript>-octreotide in neuroendocrine liver metastases

Purpose  The aim of this study is to evaluate the effectiveness of ¹¹¹In-DTPA-Phe¹-octreotide infusions after selective catheterization of the hepatic artery in inoperable metastasised liver, sst₂ receptor-positive neuroendocrine tumours due to the effect of ¹¹¹In Auger electron emission, minimising in parallel the toxicity of non-target tissue. Methods  The average dose per session administered monthly to each patient (17 cases in total) was 6.3 ± 2.3 GBq. Repetitions did not exceed 12-fold, except in one case (15 sessions). Response assessment was classified according to the Response Evaluating Criteria in Solid Tumours. CT/MRI scans were performed as baseline before, during and after the end of treatment, and monthly ultrasound images for follow-up measurements. Toxicity (World Health Organization criteria) was measured using blood and urine tests of renal, hepatic and bone marrow function. Results  Complete response was achieved in one (5.9%) patient and partial in eight (47.0%), and disease stabilization in 3 (17.7%) patients; five (29.4%) did not respond. A 32-month median survival time was estimated in 12 (70.5%). Nine of these 12 surviving had a mean target diameter shrinkage from 144 ± 81 to 60 ± 59 mm. Grade 1 erythro-, leuko- and thrombo-cytopenia occurred in three (17.6%) cases. Conclusion  In unresectable metastatic liver lesions positive for somatostatin receptors repeated, transhepatic high doses of ¹¹¹In-DTPA-Phe¹-octreotide show an effective therapeutic outcome. Given the locoregional modality character of the administration technique plus the extremely short range of ¹¹¹In Auger and internal conversion electrons emission, no nephro-, liver- or myelo-toxicity has so far been observed.     

Iodine-123 as a diagnostic imaging agent in differentiated thyroid carcinoma: a comparison with iodine-131 post-treatment scanning and serum thyroglobulin measurement

Purpose Using ¹²³I for diagnostic purposes avoids the risk of stunning for subsequent radioiodine treatment and affords an excellent image quality. In this study we assessed the role of ¹²³I in comparison with ¹³¹I post-treatment imaging in patients with thyroid cancer. Methods We compared a total of 292 ¹²³I scans with their corresponding post-treatment ¹³¹I images. Patients received a therapeutic dose of ¹³¹I following diagnostic scanning with 50–111 MBq of ¹²³I. All patients were in a hypothyroid state (>30 μIU/l) before radioiodine administration for either diagnostic or therapeutic purposes. Results In 228 out of 263 patients with a positive diagnostic scan, ¹²³I whole-body scan findings were concordant with those of corresponding post-treatment ¹³¹I images (concordance rate 87%). However, there were 44 additional foci of abnormal uptake on post-treatment ¹³¹I scans in 22 discordant cases with no impact on therapeutic management of the patients. In 13 patients, there was at least one new site on post-treatment images that had been missed on pretreatment ¹²³I images. Twenty-nine patients with a negative diagnostic scan were treated with ¹³¹I owing to a high serum thyroglobulin level (range 11.3–480 ng/ml). Radioiodine uptake sites were seen in eight post-treatment scans. In 21 pairs of whole-body scans, both the pre- and the post-treatment scan were negative (concordance rate 72.4%). Conclusion ¹²³I scanning is comparable to high-dose ¹³¹I post-treatment imaging in thyroid carcinoma patients, and ¹²³I offers excellent image quality as a diagnostic agent. It avoids disadvantages such as stunning before treatment and delivery of a high radiation dose to patients.     

Comparison of whole-body <Superscript>18</Superscript>F-FDG PET, <Superscript>99m</Superscript>Tc-MIBI SPET,and post-therapeutic <Superscript>131</Superscript>I-Na scintigraphy in the detection of metastatic thyroid cancer

The usefulness of fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in differentiated thyroid cancer (DTC) has been demonstrated by many investigators, but in only a small number of studies have FDG-PET images been compared with those obtained using other non-iodine tumour-seeking radiopharmaceuticals. In most of the studies, planar imaging was performed for comparison using thallium-201 chloride or technetium-99m 2-methoxyisobutylisonitrile (^99mTc-MIBI). Furthermore, FDG-PET studies were not always performed in the hypothyroid state with increased levels of thyroid stimulating hormone (TSH), which are known to increase FDG uptake by DTC. The aim of this study was to compare the ability of FDG-PET to detect metastatic DTC with that of ^99mTc-MIBI whole-body single-photon emission tomography (SPET) and post-therapeutic iodine-131 scintigraphy, evaluated under TSH stimulation. Nineteen patients (8 men, 11 women; age range, 38–72 years, mean 60 years; 17 thyroidectomised and 2 inoperable patients following ¹³¹I ablation of the remaining thyroid tissue; 16 papillary and 3 follicular carcinomas) with metastatic DTC underwent FDG-PET whole-body scan (WBS) and ^99mTc-MIBI SPET WBS at an interval of less than 1 week, followed by ¹³¹I therapy. The SPET images were reconstructed using the maximum likelihood expectation maximisation (ML-EM) method. All patients were hypothyroid at the time of each scan. ¹³¹I WBS was performed 3–5 days after oral administration of the therapeutic dose. A total of 32 lesions [10 lymph node (LN), 15 lung, 6 bone, 1 muscle] were diagnosed as metastases, as confirmed by histopathology and/or other imaging modalities (X-ray, US, CT, MRI, bone, ²⁰¹Tl and ¹³¹I scans). FDG-PET, ^99mTc-MIBI SPET and post-therapeutic ¹³¹I scintigraphy respectively revealed a total of 26 (81.3%), 20 (62.5%) and 22 (68.8%) lesions. These techniques respectively demonstrated nine (90.0%), eight (80.0%) and six (60.0%) LN metastases, and eleven (73.3%), seven (46.7%) and ten (66.7%) lung metastases. They each demonstrated five of the six bone metastases (83.3%). FDG-PET and ^99mTc-MIBI SPET were positive in 17 (78.3%) and 14 (63.6%) of the 22 ¹³¹I-positive lesions, respectively, and also in nine (90.0%) and six (60.0%) of the ten ¹³¹I-negative lesions, respectively. Three of the five ¹³¹I-positive and FDG-PET-negative lesions were miliary type lung metastases with a maximal nodular diameter of less than 10 mm. Comparison of FDG-PET with ^99mTc-MIBI SPET revealed concordant results in 24 lesions, and discordant results in eight lesions (seven with positive FDG-PET alone and one with positive ^99mTc-MIBI SPET alone). In conclusion: (a) even using whole-body SPET, FDG PET is superior to ^99mTc-MIBI in terms of ability to detect metastases of DTC; (b) the higher sensitivity of FDG-PET compared with the previous studies could partly be due to increased serum TSH.     

Correlation of apparent diffusion coefficients measured by 3T diffusion-weighted MRI and SUV from FDG PET/CT in primary cervical cancer

Purpose  Diffusion-weighted magnetic resonance imaging (DWI) and fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) are oncological feasible techniques. Currently, apparent diffusion coefficient (ADC) measured by DWI and standard uptake value (SUV) from FDG PET/CT have similar applications in clinical oncology. The aim of this study was to assess the correlation between ADC and SUV in primary cervical cancer. Materials and methods  Patients with documented primary cervical cancer were recruited. All participants underwent abdominopelvic DWI at 3T and FDG PET/CT within 2 weeks. For the primary tumor, ADC was measured as minimum ADC (ADC_min) and mean ADC (ADC_mean) within the whole tumor by DWI. Maximum SUV (SUV_max) and mean SUV (SUV_mean) were measured by FDG PET/CT. Results  A total of 33 patients were included. There was no significant correlation either between ADC_min and SUV_max or between ADC_mean and SUV_mean. The relative ADC_min (rADC_min) defined as ADC_min/ADC_mean ratio was significantly inversely correlated with the relative SUV_max (rSUV_max) defined as SUV_max/SUV_mean ratio (r = –0.526, P = 0.0017) in all study patients. A significantly inverse correlation between rADC_min and rSUV_max was observed in patients with adenocarcinoma/adenosquamous carcinoma (r = –0.685, P = 0.0012) and those with well-to-moderate differentiated tumor (r = –0.631, P = 0.0050). No significant correlation was demonstrated in patients with squamous cell carcinoma or poorly differentiated tumor. Conclusions  The significantly inverse correlation between rADC_min and rSUV_max in primary cervical tumor suggests that DWI and FDG PET/CT might play a complementary role for the clinical assessment of this cancer type.