Annals of Nuclear Medicine (v.23, #6)

How long the lymphoscintigraphy imaging should be continued for sentinel lymph node mapping? by Ramin Sadeghi; Mohammad Naser Forghani; Bahram Memar; Mohammad Taghi Rajabi Mashhadi; Vahid Reza Dabbagh Kakhki; Abbas Abdollahi; Seyed Rasoul Zakavi (507-510).
We assessed the need for delayed lymphoscintigraphy imaging for sentinel lymph node (SLN) biopsy in stage I and II breast cancer patients using intradermal injection of 99mTc-antimony sulfide colloid.Seventy-five patients with early-stage breast cancer were included in our study. Periareolar intradermal injections of 0.5 mCi/0.2 mL 99mTc-antimony sulfide colloid was used for the patients without previous excisional biopsy (45 patients). Two intradermal injection of 0.5 mCi/0.2 mL 99mTc-antimony sulfide colloid was used on each side of the dermal incision in patients with the history of excisional biopsy (30 patients). Anterior and lateral static images were taken at 2 min. If SLN was not visualized, delayed imaging at 5, 10, 30, 60, 90, 150, and 180 min was done (till the visualization of the SLN or 180 min). SLN was performed by the combination of gamma probe and blue dye during surgery.Sentinel lymph node detection rate was 96% (72/75). SLNs were detected on the immediate (2 min) images in 55 (73.33%) patients. In the remaining patients, the SLNs were detected first on the 5-, 10-, and 30-min images in 10 (13/33%), 5 (6.66%), and 2 (2.66%) patients, respectively. In three patients (4%), SLN was not detected by lymphoscintigraphy even on 180-min images. During surgery, SLN was not detected in these three patients either.Considering the rapid flow of 99mTc-antimony sulfide colloid in our study, lymphoscintigraphy imaging can be completed in the nuclear medicine department without any delay in sending the patient back to the surgery department. Thirty minutes after radiotracer injection seems to be the optimal time for lymphoscintigraphy and delayed imaging beyond 30 min would not be necessary.
Keywords: Delayed imaging; Breast cancer; Lymphoscintigraphy; Sentinel lymph node; 99mTc-antimony sulfide colloid

The information available on 18F-fluorodeoxyglucose (FDG) uptake on PET in radiation-induced pelvic insufficiency fracture (PIF) is limited. In this study, we reviewed the findings of FDG-PET in 10 cases with PIF.We diagnosed 83 cases of PIF in patients who received pelvic radiotherapy between Jan 1995 and Aug 2005. Among these patients, we selected 10 patients who performed FDG-PET and reviewed the FDG uptake.Mild FDG uptake was still present at 6-months after the diagnosis of PIF in two patients. Eight patients had mild and diffuse FDG uptake and two patients had intense and heterogeneous uptake. All patients had vertical uptake parallel to the sacroiliac joints and one patient had the typical ‘H’ sign associated with PIF. The maximum of standardized uptake values was variable and ranged from 2.4 to 7.2. In three patients, follow-up PET images were obtained. All patients had FDG uptake that decreased with time.The FDG-PET demonstrated a variable degree of uptake in patients with a PIF. The pattern of uptake was diffuse and vertical, parallel to the sacroiliac joints. Therefore, clinicians should be careful with the interpretation of FDG uptake around the sacroiliac joints, and keep in mind false-positive lesions such as PIFs.
Keywords: Pelvic insufficiency fracture; FDG-PET; PET/CT

Characterization of Japanese standards for myocardial sympathetic and metabolic imaging in comparison with perfusion imaging by Shinro Matsuo; Kenichi Nakajima; Shohei Yamashina; Kazuyuki Sakata; Mitsuru Momose; Jun Hashimoto; Shinichiro Kumita; Masaya Kawano; Koichi Okuda (517-522).
The standard patterns of myocardial radiotracer distribution of 123I-metaiodobenzylguanidine (MIBG) and 123I-β-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) should be defined in a Japanese population. The purpose of this study was to present and provide data on the characteristics of MIBG and BMIPP with respect to myocardial single photon emission computed tomography.The normal database included 123I-MIBG and 123I-BMIPP imaging and a 99mTc-sestamibi/tetrofosmin myocardial perfusion study. The projection images were transferred by digital imaging and communications in medicine (DICOM) format and reconstructed and analyzed with polar maps.The projection data from multiple centers were successfully transferred to a common format for SPECT reconstruction. When the average values were analyzed using a 17-segment model, MIBG uptake in the inferior and apical wall appeared to be slightly lower than anterior uptake (P < 0.05). The inferior and apical uptake of MIBG has a larger standard deviation (10.7 units in males, 12.6 units in females). BMIPP uptakes in the septal wall have higher than that of 99mTc-tracer uptake (P < 0.05).Myocardial sympathetic nerve and metabolic scintigraphy data that were specific for the Japanese population were generated and found to be different from that of perfusion tracers. The normal database can serve as a standard for nuclear cardiology work conducted in Japan.
Keywords: 123I-metaiodobenzylguanidine (MIBG); 123I-β-methyl-p-iodophenyl-pentadecanoic acid; Myocardial SPECT; Japanese Society of Nuclear Medicine (JSNM) working group

Differential diagnosis between 18F-FDG-avid metastatic lymph nodes in non-small cell lung cancer and benign nodes on dual-time point PET/CT scan by Kazuyoshi Suga; Yasuhiko Kawakami; Atsuto Hiyama; Kazurou Sugi; Kazutomo Okabe; Tsuneo Matsumoto; Kazuhiro Ueda; Nobuyuki Tanaka; Naofumi Matsunaga (523-531).
To clarify the difference of 18F-FDG uptake kinetics between FDG-avid metastatic lymph nodes (LNs) in patients with non-small-cell lung cancer (NSCLC) and FDG-avid benign LNs associated with various etiologies on dual-time point PET/CT scan, and to determine the optimal parameter for differentiation.The subjects were 134 FDG-avid metastatic LNs in 67 patients with NSCLC and 62 FDG-avid benign LNs in 61 patients with various lung disorders including NSCLC. PET/CT scan was performed at 2 time points (at 60 min and at 120 min) after intravenous injection of 4.4 MBq/kg 18F-FDG. The maximum standardized uptake value (SUVmax) on early and delayed scans and the percent change of SUVmax (%ΔSUVmax) were measured at each FDG-avid LN. The optimal parameter for differentiation was determined by the receiver-operating characteristic analysis.Delayed SUVmax was increased compared with early SUVmax in 114 (85.0%) FDG-avid metastatic LNs and 42 (67.7%) FDG-avid benign LNs, with significant higher delayed SUVmax than early values (7.0 ± 5.0 vs. 5.9 ± 3.4; P < 0.0001, and 3.0 ± 1.3 vs. 2.8 ± 1.0; P < 0.05, respectively). Early and delayed SUVmax and %ΔSUVmax in metastatic LNs were significantly higher than those in benign LNs (P < 0.0001). The optimal parameter for the differentiation was the combined use of early SUVmax > 3.0 or delayed SUVmax > 4.0, yielding sensitivity of 88.8%, specificity of 80.6%, accuracy of 86.2%, negative predictive value of 76.9%, and positive predictive value of 90.6%. It provided better results than the use of early SUVmax > 3.0 alone (P = 0.019) or the optimal parameter for %ΔSUVmax (>5%) (P = 0.012). However, 12 (19.3%) benign LNs were indistinguishable from metastatic LNs.Although dual-time point PET/CT scan enhances the difference of FDG uptake between FDG-avid metastatic and benign LNs and improves the differentiation when compared with a single scan, biopsy procedure may be still required for accurate assessment of LN status in patients with NSCLC and possible etiologies showing intensive FDG uptake in benign LNs.
Keywords: 18F-FDG; Non-small cell lung cancer (NSCLC); Lymph node; Metastasis; Dual-time point PET scan

Evaluation of utility of asymmetric index for count-based oxygen extraction fraction on dual-tracer autoradiographic method for chronic unilateral brain infarction by Katsuhiro Iwanishi; Hiroshi Watabe; Hiroshi Fujisaki; Takuya Hayashi; Yoshinori Miyake; Kotaro Minato; Masaki Naganuma; Toshiyuki Uehara; Chiaki Yokota; Hiroshi Moriwaki; Katsufumi Kajimoto; Kazuhito Fukushima; Kazuo Minematsu; Hidehiro Iida (533-539).
For diagnosing patients with ischemic cerebrovascular disease, non-invasive count-based method with 15O2 and H 2 15 O positron-emission tomography (PET) data is widely used to measure asymmetric increases in oxygen extraction fraction (OEF). For shortening study time, we have proposed dual-tracer autoradiographic (DARG) protocol in which 15O2 gas and C15O2 gas are sequentially administrated within short period. In this paper, we evaluated feasibility of the non-invasive count-based method with the DARG protocol.Twenty-three patients [67.8 ± 9.9 (mean ± SD) years] with chronic unilateral brain infarction were examined by the use of measurements of asymmetric OEF elevation. As DARG protocol, 15O2 and C15O2 gases were inhaled with 5-min interval and dynamic PET data were acquired for 8 min. Quantitative OEF (qOEF) image was computed with PET data and arterial input function. Ratio image of 15O2 and C15O2 phases of PET data was computed as count-based OEF (cbOEF) image. The asymmetric indices (AI) of qOEF (qOEF-AI) and cbOEF (cbOEF-AI) were obtained from regions of interest symmetric placed on left and right sides of cerebral hemisphere. To optimize the summation time of PET data for the cbOEF image, qOEF and cbOEF images with various summation times were compared.Image quality of cbOEF image was better than that of qOEF image. The best correlation coefficient of 0.94 was obtained when the cbOEF image was calculated from 0 to 180 s of 15O2 summed image and 340 to 440 s of C15O2 summed image.Using the appropriate summation time, we obtained the cbOEF image with good correlation with qOEF image, which suggests non-invasive cbOEF image can be used for evaluating the degree of misery perfusion in patients with chronic unilateral brain infarction. The count-based method with DARG protocol has a potential to dramatically reduce the examination time of 15O PET study.
Keywords: Dual-tracer autoradiographic method; Count-based method; Oxygen extraction fraction; Asymmetric index

18F-choline PET/CT imaging of RECIST measurable lesions in hormone refractory prostate cancer by Sandi A. Kwee; Marc N. Coel; Bevan H. Ly; John Lim (541-548).
Apply measurability criteria based on the response evaluation criteria in solid tumors (RECIST) to lesions found on 18F-choline positron emission tomography (PET)/computerized tomography (CT) in patients with hormone refractory prostate cancer.Whole-body PET followed by CT or in-line PET/CT using 3.3–4 MBq/kg of 18F-choline was performed prospectively on 30 patients with prostate cancer, castrate testosterone levels, and rising post-treatment prostate specific antigen (PSA) levels. Lesions demonstrating increased 18F-choline uptake were classified as measurable or non-measureable based on RECIST.Three patients were known previously to have RECIST measurable lesions, 10 patients had metastatic findings on radionuclide bone scan, and 17 patients had elevated serum PSA level as the only evidence of disease. Lesions demonstrating increased 18F-choline uptake were found in 28 (93%) patients. Thirty-eight PET/CT lesions from 14 patients were measurable by RECIST. Lymph node maximum standardized uptake value (SUVmax) correlated with lymph node diameter (Pearson r = 0.44, p < 0. 001). RECIST measurable lymph node SUVmax was significantly higher than that of non-measurable nodes (8.1 vs. 3.7, p < 0.0001). Detection of skeletal, prostatic, or RECIST-compatible lesions was more likely with a PSA level greater than 4.0 ng/ml (Fisher exact p = 0.0005).Lesions detected with 18F-choline PET/CT are frequently measurable by RECIST at baseline. Therefore, it may be feasible to include comparisons to RECIST in evaluations of 18F-choline as a therapeutic response marker for hormone refractory prostate cancer.
Keywords: Positron emission tomography; Fluorocholine; Prostate carcinoma

Lung epithelial permeability and inhaled furosemide: added dimensions in asthmatics by Ujwal N. Bhure; Shraddha U. Bhure; Bhairavi M. Bhatt; Sonal Mistry; S. J. Pednekar; V. V. Chari; S. A. Desai; J. M. Joshi; A. J. Paidhungat (549-557).
Lung clearance rates of inhaled 99mTc-DTPA aerosols constitute a sensitive index to evaluate the permeability changes characteristic of airway epithelial damage. It was thought that edema of the airway wall which is reported in asthma could be relieved with a diuretic like furosemide, helping to relieve the symptoms. We intended to study the effect of inhaled furosemide on lung epithelial permeability in asthmatics and smokers with the help of 99mTc-DTPA lung clearance test (LCT).The study included three groups (n = 15), viz. normal healthy controls, asymptomatic chronic smokers, and chronic persistent asthmatics. Each subject underwent the LCT twice, baseline and post-furosemide (Lasix) study, within a week’s interval. The post-furosemide study was carried out 15 min after inhalation of 10 mg of lasix. Lung epithelial permeability was determined in terms of clearance half-life (T 1/2).The baseline mean T 1/2 values for controls, smokers, and asthmatics were 50.95 ± 16.58, 20.81 ± 5.47, 24.06 ± 6.19 min, respectively. Post-lasix T 1/2 values were 50.83 ± 15.84, 20.70 ± 5.65, 41.27 ± 15.07 min, respectively. There was a significant difference (P < 0.001) in baseline and post-lasix clearance values in asthmatics only.Baseline lung epithelial permeability was altered in smokers and asthmatics compared to the controls. Furosemide was effective only in asthmatics in reverting the permeability almost back to the normal range. Inhaled furosemide was effective even in moderate and severe asthmatics. Furosemide has multiple mechanisms of action. It possibly acts at bronchial level in view of the pathology in asthmatics lying in the airways.
Keywords: Lung epithelial permeability; DTPA; Lung clearance; Asthma; Furosemide

Evaluation of 64Cu-labeled DOTA-d-Phe1-Tyr3-octreotide (64Cu-DOTA-TOC) for imaging somatostatin receptor-expressing tumors by Hirofumi Hanaoka; Hideyuki Tominaga; Keiich Yamada; Pramila Paudyal; Yasuhiko Iida; Shigeki Watanabe; Bishnuhari Paudyal; Tetsuya Higuchi; Noboru Oriuchi; Keigo Endo (559-567).
In-111 (111In)-labeled octreotide has been clinically used for imaging somatostatin receptor-positive tumors, and radiolabeled octreotide analogs for positron emission tomography (PET) have been developed. Cu-64 (64Cu; half-life, 12.7 h) is an attractive radionuclide for PET imaging and is produced with high specific activity using a small biomedical cyclotron. The aim of this study is to produce and fundamentally examine a 64Cu-labeled octreotide analog, 64Cu-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-d-Phe1-Tyr3-octreotide (64Cu-DOTA-TOC). 64Cu produced using a biomedical cyclotron was reacted with DOTA-TOC for 30 min at 45°C. The stability of 64Cu-DOTA-TOC was evaluated in vitro (incubated with serum) and in vivo (blood collected after administration) by HPLC analysis. Biodistribution studies were performed in normal mice by administration of mixed solution of 64Cu-DOTA-TOC and 111In-DOTA-TOC and somatostatin receptor-positive U87MG tumor-bearing mice by administration of 64Cu-DOTA-TOC or 64Cu-1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid-octreotide (64Cu-TETA-OC). The tumor was imaged using 64Cu-DOTA-TOC, 64Cu-TETA-OC, and FDG with an animal PET scanner. 64Cu-DOTA-TOC can be produced in amounts sufficient for clinical study with high radiochemical yield. 64Cu-DOTA-TOC was stable in vitro, but time-dependent transchelation to protein was observed after injection into mice. In biodistribution studies, the radioactivity of 64Cu was higher than that of 111In in all organs except kidney. In tumor-bearing mice, 64Cu-DOTA-TOC showed a high accumulation in the tumor, and the tumor-to-blood ratio reached as high as 8.81 ± 1.17 at 6 h after administration. 64Cu-DOTA-TOC showed significantly higher accumulation in the tumor than 64Cu-TETA-OC. 64Cu-DOTA-TOC PET showed a very clear image of the tumor, which was comparable to that of 18F-FDG PET and very similar to that of 64Cu-TETA-OC. 64Cu-DOTA-TOC clearly imaged a somatostatin receptor-positive tumor and seemed to be a potential PET tracer in the clinical phase.
Keywords: 64Cu; DOTA-d-Phe1-Tyr3-octreotide (DOTA-TOC); Somatostatin receptor

Characterization of thymic masses using 18F-FDG PET-CT by Arvind Kumar; Subodh Kumar Regmi; Roman Dutta; Rakesh Kumar; Siddhartha Datta Gupta; Prasenjit Das; Dhanapathi Halanaik; Tarun Jindal (569-577).
The resectability and survival may be improved in thymoma and thymic carcinoma with multimodality therapy. Various diagnostic imaging modalities are required for accurate diagnosis and preoperative staging of thymic masses. The present prospective study was planned to evaluate if Fluorodeoxyglucose (FDG) PET-CT can help differentiate various thymic lesions noted on conventional imaging modalities.A prospective study was undertaken in 23 patients who had shown either an anterior mediastinal mass consistent with thymic origin or suspicious for a thymic mass on contrast-enhanced computed tomography scan. All patients underwent whole body FDG PET-CT after intravenous injection of 370 MBq of FDG. The interpretation of PET-CT images was based on the following criteria: FDG uptake (present or absent), SUVmax, pattern of uptake, invasion to surrounding structures, presence of metastasis and necrosis. The results of PET-CT were correlated with the final histopathology following surgery. Statistical analysis was performed with SPSS 11.5 for Windows software. The mean SUVmax of the 3 groups of pathology was compared using the Kruskal–Wallis Test.Thymic hyperplasia had an enlarged thymus with mean SUVmax of 1.1. Low risk thymoma had large tumors and their mean SUVmax was 3. High risk thymoma had small tumors with mean SUVmax of 2.1. As a group, thymoma had mean SUVmax value of 2.3. All thymic carcinomas were large, and their mean SUVmax was 7. The difference between the mean SUVmax for thymic hyperplasia, thymoma and thymic carcinoma was statistically significant. The difference between the SUVmax of high risk and low risk thymoma was not significant. 18F-FDG PET-CT can help characterize various thymic lesions noted on conventional imaging modalities. However, larger prospective studies are further required to substantiate these findings.
Keywords: FDG PET-CT; Thymic carcinoma; Thymoma; Thymic hyperplasia

Clinical usefulness of novel cardiac MDCT/SPECT fusion image by Shinro Matsuo; Kenichi Nakajima; Nasima Akhter; Hiroshi Wakabayashi; Junichi Taki; Koichi Okuda; Seigo Kinuya (579-586).
We evaluated the relationship between computed tomography angiography (CTA) and SPECT, and assessed to determine the clinical usefulness of the fusion image using CTA and myocardial perfusion imaging (MPI).Forty-one consecutive patients [after coronary artery bypass operation (n = 13) and suspected stenosis (n = 28)] underwent MPI and CTA. SPECT/CTA fused images were generated.In total, 687 segments including bypass graft in 164 coronary arteries were analyzed. Myocardial ischemia on MPI was observed in 11 patients among 28 with CTA abnormalities, one had both ischemia and infarction, and 7 had only infarction. Segment-based analysis showed that ischemia was found in 14 segments (24%) among 59 stenoses on CTA. Forty stenotic segments (69%) were not associated with perfusion abnormality. The rest 5 stenotic segments were considered equivocal (8%). A fusion image made it possible to associate perfusion defects with its corresponding coronary artery in 4 out of 5 equivocal lesions on side-by-side analysis. Patients with incremental diagnostic information on SPECT/CTA fusion (n = 4) had significant smaller coronary diameter than that of not-improved coronary vessels (2.0 ± 0.4 vs. 3.9 ± 0.4 mm, p = 0.001).Cardiac fusion imaging accurately diagnosed functionally relevant coronary stenosis. SPECT/CTA fusion images in coronary artery disease may provide added diagnostic information on functional relevance of coronary artery disease.
Keywords: Fusion image; CT angiography; Culprit lesion; SPECT

Effect of respiratory motion on quantitative myocardial gated SPECT: a simulation study by Ahmad Bitarafan-Rajabi; Hossein Rajabi; Feridoon Rastgou; Ali Akbar Sharafi (587-593).
Respiratory motion is a potential cause of artefact and downgrading the quality of ECG-gated single photon emission computed tomography (SPECT) images that may result in clinical misinterpretation. We studied qualitatively the effects of respiratory motion on gated SPECT myocardial perfusion and function using Monte Carlo simulated data.NCAT phantom was used to model a human torso. The cardiac and respiratory cycles of torso were 1 and 5 s, respectively. Eight realizations of the phantom, having diaphragmatic motion amplitudes of 0–7 cm were generated. SimSET Monte Carol simulator was used to image the phantom and generate gated studies of 16 frames per cardiac cycle.Our results demonstrated the underestimation of left ventricle end-diastolic, end-systolic, stroke volumes and ejection fraction and overestimation of wall motion and wall thickening (p < 0.01). In addition, the mean percentage of count in the basal-inferior, mid-inferior, apical-inferior, basal-septal and mid-septal segments were significantly lower due to respiratory motion when compared with control (p < 0.01). The changes in uptake were not significant in the apex, antroapical, apicoseptal, apicolateral, mid-anterior, basal-anterior, mid-lateral and basal-lateral segments.Respiratory motion has significant effect on the calculation of the left ventricular functional and regional myocardial perfusion in the GSPECT. The amount of deterioration and quality distortion of the images depends on the amplitude of the diaphragmatic motion.
Keywords: Respiratory motion; ECG-gated SPECT; Ejection fraction; Myocardial perfusion

Simultaneous FDG PET+/Glut1+ lung and FDG PET−/Glut1− subcarinal lymph node metastases from prostate cancer by Amir H. Khandani; William K. Funkhouser; Richard Feins; Mark A. Socinski (595-597).
A 78-year-old man with a history of prostate cancer and a rise in PSA presented with a new left lung mass, detected on computed tomography (CT). Positron emission tomography (PET)–CT (PET–CT) scan with 18-F fluorodeoxyglucose glucose revealed intense uptake in the lung mass without any other areas of abnormal uptake. Surgical resection of the mass and mediastinal lymph node dissection revealed metastatic adenocarcinoma from prostate cancer in the left lung mass (tumor size 5 cm) as well as in a subcarinal lymph node (tumor size 1.9 cm), which were identical on hematoxylin and eosin stains with a Gleason score of 8. The size of the subcarinal lymph node metastasis could not explain its non-visualization on PET. Glut1 stains of the lung mass were positive with moderate (2+ out of maximum 3+) reactivity in 95% of the carcinoma cells, whereas Glut1 stains of the subcarinal lymph node were negative with faint (1+ out of maximum 3+) reactivity in ca. 30% of the carcinoma cells. The low Glut1 expression in the subcarinal lymph node is the most likely explanation for its non-visualization on PET.
Keywords: FDG PET; Metastases; Glut; Prostate cancer

Incidental focal F-18 FDG accumulation in lung parenchyma without abnormal CT findings by Jung-Min Ha; Shin-Young Jeong; Young-Soon Seo; Seong-Young Kwon; Ari Chong; Jong-Ryool Oh; Ho-Chun Song; Hee-Seung Bom; Jung-Joon Min (599-603).
F-18 fluorodeoxyglucose (FDG) PET/CT that simultaneously offers anatomic and metabolic information is widely used and has become an effective modality in many clinical fields, especially oncology. For accurate interpretation, it is necessary to understand false-positive findings in the F-18 FDG PET image, such as physiologic conditions, findings related to patients’ medical and surgical histories, normal variants, and artificial conditions. We report three cases of incidental focal F-18 FDG accumulation in lung parenchyma without abnormal CT findings in the PET/CT images. In the primary PET/CT studies, two cases showed single and one case showed multiple FDG foci in the lung without any CT abnormalities. All FDG accumulations disappeared in PET/CT studies repeated 1–3 days after the primary scannings. These artifacts are probably related to microembolisms attributable to the intravenous injection of F-18 FDG. Therefore, a cautious interpretation of the correspondence between anatomic and metabolic images is required and repeated PET/CT is helpful.
Keywords: FDG accumulation; PET/CT; Microembolism

99mTc-TRODAT-1 SPECT study in evaluation of Holmes tremor after thalamic hemorrhage by Yueh-Feng Sung; Yaw-Don Hsu; Wen-Sheng Huang (605-608).
Holmes tremor is also known as rubral or midbrain tremor. The tremor usually involves lesions near the red nucleus and the nerve fiber tracts originating in the cerebellum and the substantia nigra. We report a case of a 62-year-old woman who presented with Holmes tremor 5 months after a left thalamic hemorrhage, with a partial recovery 3 years later. Sequential technetium-99mTRODAT-1 single-photon emission computed tomography (SPECT) of the patient’s brain revealed partially improved tracer uptake reduction in the striatums, particularly on the left side. We propose that involvement of both the nigrostriatal and the dentate-rubro-thalamic pathways are essential in the pathogenesis of Holmes tremor after a thalamic lesion, and regeneration of the nigrostriatal system is possible in this type of tremor after the initial degeneration. The 99mTc-TRODAT-1 SPECT study is a useful and convenient tool for evaluating the nigrostriatal dopamine function in patients with Holmes tremor.
Keywords: Holmes tremor; Thalamic hemorrhage; Dopamine transporter; 99mTc-TRODAT-1; SPECT