Diagnostic value of [ 68 Ga]Ga-Pentixafor PET/CT in malignant melanoma: a pilot study.

OBJECTIVE: To evaluate the diagnostic value of [ 68 Ga] Ga-Pentixafor in malignant melanoma patients. METHODS: In this prospective study, patients with histology-proven melanoma were included and underwent [ 18 F]fluoro-D-glucose ([ 18 F]FDG) and [ 68 Ga] Ga-Pentixafor PET/computed tomography (CT) within a week. Suspicious lesions were interpreted as benign vs. malignant, and the corresponding semi-quantitative PET/CT parameters were recorded and compared. RESULTS: Twelve consecutive melanoma patients (mean age: 60 ±â€…6) were included. Two patients were referred for initial staging, two for detecting recurrence and eight for evaluating the extent of metastases. Overall, [ 18 F]FDG PET/CT showed 236 tumoral lesions, including two primary tumors, two recurrent lesions, 29 locoregional metastases and 203 distant metastases. In [ 68 Ga]Ga-Pentixafor PET/CT, 101 tumoral lesions were detected, including two primary tumors, one recurrence, 16 locoregional metastases and 82 distant metastases. Notably, a documented brain metastasis was only visualized on [ 68 Ga]Ga-Pentixafor PET/CT images. Compared with [ 18 F]FDG, [ 68 Ga]Ga-Pentixafor PET/CT provided a 42% detection rate. Regarding semi-quantitative measures, the intensity of uptake and tumor-to-background ratios were significantly lower on [ 68 Ga]Ga-Pentixafor PET/CT [average maximum standard uptake value (SUV max ) of 2.72 ±â€…1.33 vs. 11.41 ±â€…14.79; P value <0.001 and 1.17 ±â€…0.53 vs. 5.32 ±â€…7.34; P value <0.001, respectively]. CONCLUSION: When comparing [ 68 Ga]Ga-Pentixafor PET/CT with [ 18 F]FDG PET/CT, not only did [ 68 Ga]Ga-Pentixafor PET/CT detect fewer lesions, but the intensity of uptake and the TBRs were also lower on [ 68 Ga]Ga-Pentixafor PET/CT. Thus, our results may indicate a limited potential of this novel tracer in cutaneous melanoma patients compared to [ 18 F]FDG PET/CT. Given the lower TBRs, applying this radiotracer in radioligand therapies is also questionable.

Whole-body low-dose CT can be of value in prostate cancer decision-making: a retrospective study on 601 patients.

OBJECTIVES: To evaluate the diagnostic value of whole-body low-dose computed tomography (CT) to detect bone metastasis in prostate cancer (PCa) patients and its possible utility in therapeutic decision-making. Also, to determine the valuable CT features for lesion characterisation. METHODS: This IRB-approved retrospective study reviewed PCa patients who underwent 68Ga-PSMA PET/CT in our centre from March 2017 to August 2022. Two board-certified radiologists and one nuclear medicine specialist reported all whole-body low-dose CT scans separately, unaware of the 68Ga-PSMA-PET results. The per-lesion and per-patient diagnostic performances were calculated. Also, the significance of CT features was evaluated. Moreover, the inter-observer agreement was analysed. A two-tailed p value < 0.05 was considered significant. RESULTS: From 727 reviewed PCa patients, 601 (mean age = 68.7 ± 8.1) were found to be eligible, including 211 (35.1%) referrals for initial staging and 390 (64.9%) for evaluating the extent of the disease after biochemical recurrence. Per-patient diagnostic analysis for three reviewers showed 81.0-89.4% sensitivity and 96.6-98.5% specificity in detecting osteo-metastasis. It was able to correctly detect high-burden disease based on both CHAARTED and LATITUDE criteria. Regarding the value of underlying CT features, size > 1 cm, ill-defined borders, presence of soft-tissue component, and cortical destruction were statistically in favour of metastasis. Also, Hu > 900 was in favour of benign entities with 93% specificity. CONCLUSIONS: Although not as accurate as 68Ga-PSMA PET/CT, whole-body low-dose CT might precisely classify PCa patients considering therapeutic decision-making. Additionally, we proposed diagnostic CT features that could help radiologists with better characterisation of the detected lesions. CRITICAL RELEVANCE STATEMENT: The whole-body low-dose CT can be considered valuable in the clinical decision-making of prostate cancer patients. This modality may obviate performing multiple imaging sessions and high-cost scans in patients diagnosed with the high-burden disease.

Diagnostic value of [ 68 Ga]Ga-Pentixafor versus [ 18 F]FDG PET/CTs in non-small cell lung cancer: a head-to-head comparative study.

OBJECTIVE: In this study, we aimed to compare the diagnostic value of [ 68 Ga]Ga-Pentixafor and [ 18 F]FDG PET/CT in the evaluation of non-small cell lung cancer (NSCLC) patients. METHODS: Patients with pathology-proven NSCLC were prospectively included. Patients underwent [ 18 F]FDG and [ 68 Ga]Ga-Pentixafor PET/CT within 1 week. All suspicious lesions were interpreted as benign or malignant, and the corresponding PET/CT semi-quantitative parameters were recorded. A two-sided P -value <0.05 was considered significant. RESULTS: Twelve consecutive NSCLC patients (mean age: 60 ±â€…7) were included. All patients underwent both [ 18 F]FDG and [ 68 Ga]Ga-Pentixafor PET/CT scans with a median interval of 2 days. Overall, 73 abnormal lesions were detected, from which 58 (79%) were concordant between [ 18 F]FDG and [ 68 Ga]Ga-Pentixafor PET/CT. All primary tumors were clearly detectable in both scans visually. Also, [ 68 Ga]Ga-Pentixafor PET/CT demonstrated rather comparable results with [ 18 F]FDG PET/CT scan in detecting metastatic lesions. However, malignant lesions demonstrated significantly higher SUVmax and SUVmean in [ 18 F]FDG PET/CT ( P -values <0.05). Regarding the advantages, [ 68 Ga]Ga-Pentixafor depicted two brain metastases that were missed by [ 18 F]FDG PET/CT. Also, a highly suspicious lesion for recurrence on [ 18 F]FDG PET/CT scan was correctly classified as benign by subsequent [ 68 Ga]Ga-Pentixafor PET/CT. CONCLUSION: [ 68 Ga]Ga-Pentixafor PET/CT was concordant with [ 18 F]FDG PET/CT in detecting primary NSCLC tumors and could visualize the majority of metastatic lesions. Moreover, this modality was found to be potentially helpful in excluding tumoural lesions when the [ 18 F]FDG PET/CT was equivocal, as well as in detecting brain metastasis where [ 18 F]FDG PET/CT suffers from poor sensitivity. However, the count statistics were significantly lower.

Non-Cutaneous Melanoma, Findings and Prognostic Value of FDG PET/CT: A Case Series of 23 patients and review of the literature.

Objectives: Non-cutaneous malignant melanomas (NCM) are rare malignancies. Due to their nonspecific symptoms, they present later in life. The value of FDG PET/CT in this group of patients is not clear. The aim of this study is to assess the role of FDG PET/CT in the management of NCM and its prognostic implication. Methods: We retrospectively selected twenty-three patients with a diagnosis of NCM evaluated with FDG PET/CT in Shariati hospital between 2019 and 2021. The PET/CT data were reviewed and compared with available conventional imaging findings. Five patients died within five months. The surviving patients were followed within a time interval of 7 to 27.5 months after their PET/CT study, regarding their disease status. Results: Among 23 patients (8 ocular, 5 sinonasal, 3 pharyngeal, 2 anorectal, 2 vulvovaginal, and 3 unknown primaries), PET/CT was able to detect residual primary disease, assess treatment response, and reveal or exclude metastases. Additional lesions compared to conventional imaging were found in five, while in one with brain metastases PET/CT was unable to detect lesions on MRI. Thirteen patients had negative PET/CT finding of which 11 (85%) did not have remarkable finding on follow-up. Metastatic disease was recognized in eight. Patients with extensive metastases on FDG PET/CT had a poorer outcome. Conclusion: Similar to cutaneous melanoma, PET/CT is valuable in the management of NCM patients and is superior to conventional imaging modalities, with the exception of brain metastases. Patients with negative PET/CT findings have a better outcome as opposed to patients with significant positive PET/CT findings.

Diagnostic value of lacrimal scintigraphy in the evaluation of lacrimal drainage system obstruction: a systematic review and meta-analysis.

PURPOSE: A systematic review and meta-analysis to evaluate the diagnostic performance of lacrimal scintigraphy (LS) versus anatomical methods in the evaluation of the nasolacrimal duct obstruction (NLDO). MATERIALS AND METHODS: A systematic search was performed using electronic bibliographic databases until the end of May 2021. Inclusion criteria: (a) used LS as a diagnostic method to evaluate NLDO; (b) used anatomical studies [including syringing, irrigation, probing, and dacryocystography (DCG)] as reference tests; and (c) provided adequate crude data. A hierarchical method was used to pool the sensitivity and specificity. The hierarchical summary receiver-operating characteristic model was performed. Additionally, the studies' heterogeneity and publication bias were analyzed. All analyses were conducted by the 'Midas' module of STATA 16. RESULTS: Twelve articles (with 14 separate populations) were considered eligible to enter the meta-analysis. They were divided into two groups based on the reference standard method, called irrigation and DCG groups. In the irrigation group, the pooled sensitivity and specificity were 89% [95% confidence interval (CI), 72-96%] and 25% (95% CI, 8-56%), respectively. In DCG group, the pooled sensitivity and specificity were 97% (95% CI, 85-100%) and 27% (95% CI, 0.12-0.49), in turn. CONCLUSION: LS is a sensitive modality to evaluate the anatomical obstruction of NLD. In contrast, it shows low pooled specificity compared with anatomical methods. Thus, LS can be used as the first noninvasive modality for the evaluation of epiphora. However, in case of any abnormality, confirmatory procedures are required.

68Ga-DOTATATE Uptake in an Intraosseous Hemangioma, as a Potential Cause of False-Positive PET/CT Finding, Simulating Tumoral Involvement.

ABSTRACT: We present the case of a 32-year-old man with a history of hypophosphatemia and multiple bone fractures, being evaluated at our center for a potential mesenchymal tumor. 68Ga-DOTATATE PET/CT revealed a highly 68Ga-DOTATATE-avid lesion in the ethmoidal sinus extending to the nasal cavity. Following resection, histologic examination of the specimen confirmed the diagnosis of "intraosseous hemangioma," a potential cause of false-positive finding of 68Ga-DOTATATE PET/CT imaging in patients being evaluated for occult malignancies, especially at the traumatic/fractured sites.

Effect of Diet on Physiologic Bowel 18F-FDG Uptake.

Intestinal 18F-FDG uptake is variable in whole-body PET/CT. In cancer patients, particularly those suspected of relapse or metastasis, 18F-FDG absorption might interfere with scan interpretation. This study evaluated the effect of diet on intestinal 18F-FDG absorption. Methods: In total, 214 patients referring for oncologic 18F-FDG PET/CT participated. They were randomly divided into 2 groups and asked to follow either a routine diet (RD) or a low-carbohydrate, high-fat diet (LCHFD) for 24 h before the study. The small bowel and different parts of the colon (the cecum; the ascending, transverse, and descending segments; and the hepatic and splenic flexures) were evaluated and visually interpreted by nuclear medicine experts. Bowel uptake was graded through comparison with that in the liver as absent, mild, moderate, or severe. Results: Significantly higher 18F-FDG uptake in the descending colon (P = 0.001) and small intestine (P = 0.01) was observed in the RD group than in the LCHFD group. After patients with bowel cancer were omitted from the statistical analysis, no significant differences in the final results were seen. Conclusion: An LCHFD for 24 h before 18F-FDG PET imaging resulted in lower 18F-FDG uptake in the descending colon and small bowel than did an RD, assisting the interpreting physician by reducing the intestinal activity interference for more accurate diagnostic interpretation.

A Prospective Study on [68Ga]-PSMA PET/CT Imaging in Newly Diagnosed Intermediate- and High-Risk Prostate Cancer.

OBJECTIVES: Prostate-specific membrane antigen (PSMA) ligand positron emission tomography/computed tomography (PET/CT) is an emerging modality to detect metastatic disease in patients with prostate cancer (PCa). This prospective study aimed to evaluate the role of [68Ga]-PSMA PET/CT in the initial workup of intermediate and high-risk PCa. METHODS: Twenty-five patients with newly transrectal ultrasound biopsy-proven, untreated intermediate- and high-risk PCa (mean age, 68.5±6.2 years; range 55-83 years) were enrolled in this prospective study between September 2018 and June 2020 and underwent a [68Ga]-PSMA PET/CT examination. All images were analyzed both visually and semiquantitatively by measuring the maximum standardized uptake value (SUVmax) of the primary prostatic tumor and metastatic lesions. The diagnostic sensitivity of [68Ga]-PSMA PET/CT for the diagnosis of PCa was established by histopathology as the reference standard. The associations between SUVmax of the primary tumors and prostate-specific antigen (PSA) levels, Gleason scores (GSs), and metastatic extent of the disease were studied. RESULTS: All patients had a positive [68Ga]-PSMA PET/CT exam. Seventeen patients (58%) showed [68Ga]-PSMA avidity in both prostate lobes and 8 (32%) had unilateral uptake. SUVmax in the primary tumor significantly correlated with serum PSA values (r=0.57, P=0.003). PSMA PET/CT depicted regional lymph node metastases in 32% of patients, distant lymph node metastases in 20%, osseous metastases in 16% and pulmonary metastases in 8% of patients. Sixty percent of PSMA-positive bone metastases and 21.4% of intraprostatic tumoral lesions were missed on the contemporaneous bone scintigraphy and magnetic resonance imaging, respectively. CONCLUSION: [68Ga]-PSMA PET/CT shows promise as a valuable imaging modality with high diagnostic sensitivity in the setting of intermediate and high-risk PCa. Moreover, the SUVmax of the primary tumor has a positive correlation with PSA levels at the time of the scan.

FDG PET/CT of an Advanced Case of Malignant Nerve Sheath Tumor of Pleura.

ABSTRACT: We present a rare case of malignant nerve sheath tumor of pleura referred for the evaluation of metastases and local invasion. FDG PET/CT demonstrated a hypermetabolic tumoral lesion extensively involving the right pleura with no involvement of mediastinal structures or pulmonary parenchyma and no clear evidence of distant metastasis. Malignant nerve sheath tumor of pleura is an extremely rare entity, and FDG PET/CT is valuable in demonstrating the extent of disease and can have potential role for postsurgical as well as postchemotherapy assessment of possible residual disease.

99mTc-PSMA SPECT/CT Versus 68Ga-PSMA PET/CT in the Evaluation of Metastatic Prostate Cancer.

BACKGROUND: 99mTc-prostate-specific membrane antigen (PSMA) SPECT/CT is less expensive and readily available modality compared with 68Ga-PSMA PET/CT for imaging prostate cancer (PC). The aim of this study is to compare the value of these 2 modalities in patients confirmed or suspicious to have metastatic prostate cancer. PATIENTS AND METHODS: Twenty-two patients with the mean age of 66.6 ± 10.1 years were studied using 99mTc-PSMA SPECT/CT and 68Ga-PSMA PET/CT, with less than 7 days interval between the 2 imaging procedures. Whole-body PET/CT was done 60 minutes after IV injection of 185 MBq (5 mCi) of 68Ga-PSMA. 99mTc-PSMA SPECT/CT was performed 3 hours after IV injection of 555 to 740 MBq (15-20 mCi) of 99mTc-PSMA. The images of each modality were interpreted independently, and the results were compared according to patient-based as well as region-based analyses. RESULTS: In patient-based evaluation, both 99mTc-PSMA SPECT/CT and 68Ga-PSMA PET/CT scans were positive in 95.45% (21/22). In region-based evaluation, 68Ga-PSMA PET/CT detected 53 regions (median of 2 regions per patient; range, 0-5), whereas 43 (median of 2 regions per patient; range, 0-5) were detected by 99mTc-PSMA SPECT/CT. Most of these differences could be explained by lower detection rate of 99mTc-PSMA SPECT/CT in prostate bed (n = 6). PET/CT detected more involved regions than SPECT/CT (P = 0.007), whereas similar frequency of extraprostatic lesions were diagnosed in both modalities (P = 0.102). Significant correlation was also demonstrated between serum prostate-specific antigen level and imaging parameters of disease extension detected by 2 modalities. CONCLUSIONS: 99mTc-PSMA SPECT/CT could be a potential substitute for 68Ga-PSMA PET/CT in high-risk patients, except when evaluation of prostate bed is of major concern.

The role of FDG PET/CT in the evaluation of treatment response in a case of calcified ovarian metastases.

Evaluation of calcified metastatic lesions by conventional imaging can be challenging. Ovarian cancer metastases can present with calcification which might increase in size and number following therapy. It is not entirely clear whether these calcifications are associated with tumor response or disease progression. Calcified lesions which do not change in size or configuration are particularly problematic when assessed by RECIST criteria. Positron emission tomography (PET)/computed tomography (CT) is of particular value as it demonstrates the metabolic activity of the calcified lesions, in addition, it might reveal metastases in unexpected sites. We report a case of serous papillary ovarian cancer with extensive abdomino-pelvic calcified metastases referred for evaluation of therapy response. Despite being reported as stable disease on CT evaluation, we observed increased metabolic activity in the calcified lesions both on CT-attenuation corrected and non-attenuation corrected images, which was indicative of inadequate response to therapy. PET/CT is an ideal modality in follow-up of patients with ovarian cancer presenting with calcified metastatic tumoral deposits.

68Ga-DOTATATE PET/CT Compared with 131I-MIBG SPECT/CT in the Evaluation of Neural Crest Tumors.

OBJECTIVES: 68Ga-DOTATATE positron emission tomography (PET)/computed tomography (CT) has shown promising results in imaging of neural crest tumors (NCT). Herein, we compared the performance of 68Ga-DOTATATE PET/CT and 131I-MIBG single photon emission computed tomography (SPECT)/CT in the initial diagnosis, staging and follow-up of patients with NCTs. METHODS: Twenty-five patients (males:females=8:17; age range=2-71 years) with clinically proven or suspicious neuroblastoma, pheochromocytoma (PCC) or paraganglioma (PGL) were enrolled in this prospective study and underwent both 68Ga-DOTATATE PET/CT and 131I-MIBG SPECT/CT. A composite reference standard derived from histopathological information, together with anatomical and functional imaging findings, was used to validate the results. Imaging findings were assessed on a per-patient and on a per-lesion basis. Sensitivity and accuracy were assessed using McNemar's test. RESULTS: Referring to radiological imaging and histopathological findings as reference standard, 68Ga-DOTATATE and 131I-MIBG scans showed a sensitivity and accuracy of (100%, 96%) and (86.7%, 88%), respectively, on a per-patient basis. In PCC/PGL patients, on a per-patient basis, the sensitivity of 68Ga-DOTATATE was 100% and that of 131I-MIBG was 77.8%. In neuroblastoma patients, on a per-patient basis, the sensitivities of both 68Ga-DOTATATE and 131I-MIBG were 100%. Overall, in this patient cohort, 68Ga-DOTATATE PET/CT identified 52 lesions and 131I-MIBG SPECT/CT identified only 30 lesions. On a per-lesion analysis, 68Ga-DOTATATE was found to be superior to 131I-MIBG in detecting lesions in all anatomical locations, particularly osseous lesions. According to the McNemar test results, differences were not statistically significant. CONCLUSION: This relatively small patient cohort suggests 68Ga-DOTATATE PET/CT be superior to 131I-MIBG SPECT/CT in providing particularly valuable information for both primary staging and follow-up in patients with NCT.

Effects of mobilized peripheral blood stem cells on treatment of primary lower extremity lymphedema.

OBJECTIVE: Lymphedema is a chronic debilitating disease characterized by the accumulation of fluid in the extremities as a result of lymphatic system impairment. Current treatments fail to restore the functionality and structural integrity of the lymphatic vessels lost in this condition. In this study, autologous mobilized peripheral blood stem cell transplantation was used and its potential efficacy and safety were evaluated in treating this condition. METHODS: Ten patients with primary lymphedema in the lower extremity received granulocyte-colony stimulating factor subcutaneously for 4 days, to stimulate stem cell mobilization, after which 200 to 250 mL of blood was drawn from each patient and used to collect stem cells. Mobilized stem cells were counted by flow cytometry with International Society of Hematotherapy and Graft Engineering method. In two sessions, 3 weeks apart, these stem cells were injected subcutaneously in the affected limb at approximately 80 points, along the lymphatic vessels. Each patient was followed for 6 months, during which changes in the limb volume and circumference were measured. Lymphangiogenesis was evaluated by biopsy, the lymphoscintigraphic transport index was calculated using Lymphoscintigraphy, and quality of life was surveyed. RESULTS: In this study, patients received on average 9.5 ± 6.8 × 108 mononuclear cells (which divided into 2 × 106 CD34+ cells for each session) in two sessions. The volume of the lower limbs decreased in 60% of patients. One patient showed a slight increase in the volume of lower limbs and three showed no change. The average limb volume was 4469.41 ± 1760.71 cm3, which on average differed from the average initial limb volume by 232.88 ± 392.53 cm3. Quality of life was reported as slightly increased in 60% of patients. The lymphoscintigraphic transport index suggested improvement in 60% of the patients. Likewise, tissue samples showed a 60% increase in lymphatic vessels. CONCLUSIONS: Subcutaneous injection of autologous hematopoietic stem cells harvested from peripheral blood into patients with primary lower limb lymphedema is feasible, potentially effective, and without serious adverse effects. However, a larger scale study with more patients is needed to validate our results. Last, to increase the effectiveness of this treatment, the optimal dose of cells injected and the requirement for additional growth factors need further study.

Diagnostic fficiency of 68Ga-DOTATATE PET/CT as ompared to 99mTc-Octreotide SPECT/CT andonventional orphologic odalities in euroendocrine umors.

OBJECTIVES: In view of somatostatin receptor (SSR) expression on cell membranes of the majority of neuroendocrine tumors (NETs), functional imaging exploiting analogs of SSR alongside the anatomical imaging is the mainstay of this diagnostic modality. In this prospective study, we assessed and directly compared the diagnostic parameters of 68Ga-DOTATATE PET/CT and 99mTc-Octreotide SPECT/CT, as well as CT/MRI. METHODS: Twenty-five NET patients, either histologically proven or highly suspicious for NET, who were referred for Octreotide Scan were enrolled in this prospective study. They all underwent 99mTc-Octreotide SPECT/CT and then 68Ga-DOTATATE PET/CT. A blind interpretation was conducted for each imaging as well as for the previously obtained conventional imaging (CT or MRI). The patient-based and lesion-based analysis were conducted and the results of the three modalities were compared. The histopathologic confirmation or follow-up data were considered as the gold standard. Also, the impact of 68Ga-DOTATATE PET/CT on the patient's management was assessed. RESULTS: Overall, 77 lesions in 14 patients, 135 in 19 and 86 in 16 were detected on 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively. On patient-based analysis, the sensitivity was 65%, 90% and 71% for 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively. Also, the specificity was 80%, 80% and 75% for 99mTc-Octreotide SPECT/CT, 68Ga-DOTATATE PET/CT and CT/MRI, respectively. The correlation between 68Ga-DOTATATE PET/CT and 99mTc-Octreotide SPECT/CT results was significant (=0.02; kappa value=0.57), no correlation, however, was depicted with CI (=0.07; kappa value=0.35). On lesion-based analysis, 68Ga-DOTATATE PET/CT found more organs (=0.02) and lesions (=0.001) in comparison with 99mTc-Octreotide SPECT/CT and also more lesions in comparison with CT/MRI (=0.003). In addition, comparing with 99mTc-Octreotide SPECT/CT and CT/MRI, 68Ga-DOTATATE PET/CT revealed more data in 44% and 36% of the patients, resulting in management modification in 24% and 20%, respectively. CONCLUSION: Comparing with 99mTc-Octreotide SPECT/CT and CT/MRI, 68Ga-DOTATATE PET/CT provided more sensitivity and specificity in patients with NETs showing more involved organs as well as tumoral lesions. Also, 68Ga-DOTATATE PET/CT led to change of management in up to one-fourth of the patients, especially in a sub-group re-evaluated for recurrence.

A Rare Presentation of Colorectal Cancer with Unusual Progressive Intramuscular and Subcutaneous Metastatic Spread.

Colorectal carcinoma is one of the most common causes of cancer-related death, worldwide. Recently, due to the introduction of novel imaging and therapeutic techniques, five-year survival of patients has increased. However, distant metastasis is still expected in half of the patients. Colorectal cancer tends to target the abdominal cavity, liver, lungs, and bones as the common sites of metastasis. Nevertheless, rare cases of muscle metastasis have been reported. This report presents a 23-year-old male, who despite chemotherapy, demonstrated gradual progressive disease and metastases to the submandibular region, lungs, adrenal gland as well as muscles and subcutaneous tissues. He had developed multiple asymptomatic muscular metastases metachronously over two-year time period discovered on an 18FDG-PET/CT, namely in the deltoid, external oblique abdominis, rectus abdominis, and quadriceps muscles, as well as one of the extrinsic muscles of the tongue. The presence of distant, especially extrahepatic metastasis, adversely affects the prognosis of colon carcinoma. Since limited cases of muscle metastasis have been reported in carcinoma of colon, the underlying pathophysiology, optimum treatment, and prognostic issues are yet to be substantiated.

The Value of Technetium-99m Labeled Alpha-Melanocyte-Stimulating Hormone (99mTc-α-MSH) in Diagnosis of Primary and Metastatic Lesions of Malignant Melanoma.

OBJECTIVES: Malignant melanoma is the most lethal type of skin cancers with unfavorable prognosis. Alpha-MSH peptide analogues have a high affinity for melanocortine-1 (MC1) receptors on melanocytes over expressing in malignant melanoma cells. Pre-clinical studies have shown promising results for radiolabeled MSH imaging in this malignancy. The purpose of this study is to assess the diagnostic value of 99mTc-α-MSH imaging in malignant melanoma. METHODS: Twenty-one patients (13 men) with pathologically confirmed malignant melanoma with or without metastatic distribution were included in this study. 740-1110 MBq 99mTc-α-MSH was injected and whole body scans were performed 20, 120 and 240 minutes post injection and were assessed both qualitatively and semi-quantitatively using target (T) to background (BG) ratio. RESULTS: The T/BG ratio for the primary tumor bed was 2.51±2.26, 2.56±2.48 and 1.92±1.79 minutes in the whole body scans 20, 120 and 240 minutes post injection, respectively. The sensitivity, specificity, negative and positive predictive values were 75%, 80%, 50% and 92% for primary lesion and 25%, 100%, 68% and 100% for distant metastasis, respectively. CONCLUSION: 99mTc-α-MSH is a newly introduced agent for diagnosis of tumoral lesions in malignant melanoma. Our study showed a high sensitivity with this modality in primary lesions as well as lymph node involvements. However the detection rate was not high in distant metastasis. The preliminary results are promising especially as a new complementary imaging method in management of malignant melanoma.

Reverse perfusion pattern in myocardial perfusion imaging using technetium-99m-sestamibi in patients with intermediate risk for coronary artery disease in relation to the time of acquisition and intensity of visceral uptake as artifactual causes.

OBJECTIVE: With respect to the equivocal value of the reverse perfusion pattern (RPP) in technetium-99m (Tc)-sestamibi myocardial perfusion imaging, a study was carried out to evaluate this pattern in association with the presence or absence of coronary artery disease (CAD) and other underlying factors, mainly the time of acquisition and the presence of intense visceral uptake. PATIENTS AND METHODS: We prospectively studied 102 patients with a moderate risk of CAD (41 men and 61 women, mean age: 56.5±9.2 years) without a previous history of documented CAD, myocardial infarction, or revascularization. Myocardial perfusion imaging was performed using a 2-day dual-phase protocol with the stress and rest images, each obtained 15, 120, and 180 min after an injection of 666-814 MBq Tc-MIBI. According to the time of image acquisition, the following five protocols were defined, A: 15/15 min, B: 15/180 min, C: 180/180 min, D: 180/15 min, and E: 120/120 min for stress/rest images, respectively. RESULTS: The odds of RPP were higher in the cases with more intense infradiaphragmatic visceral uptake on rest-phase images of the protocols A and D (odds ratios=1.2-7.8 and 1.2-7.5, respectively). Our results showed that RPP is related to incorrect normalization. Also, diabetes, sex, and CAD did not correlate with RPP. CONCLUSION: This study found no relationship between RPP and CAD, diabetes mellitus, and sex; however, an association was found between RPP and incorrect normalization because of the variation of visceral uptake intensity in relation to the time of acquisition at stress and rest phases favoring the artifactual base of this pattern.

A 99mTc-tricine-HYNIC-labeled Peptide Targeting the Melanocortin-1 Receptor for Melanoma Imaging.

Melanocortin-1 (MC1) receptor is an attractive melanoma-specific target for the development of α-MSH peptide based imaging and therapeutic agents. In this work a new lactam bridge α-MSH analogue was synthesized and radiolabeled with 99mTc via HYNIC chelator and tricine as co-ligand. Also, stability in human serum, receptor bound internalization and tissue biodistribution in tumor bearing nude mice were thoroughly investigated. Radiolabeling with 99mTc was performed at high specific activities (163MBq/nmol) with an acceptable labeling yield (>98%). The radioligand showed specific internalization into B16/F10 cells (13.35 ± 0.9% at 4 h). In biodistribution studies, a receptor-specific uptake was observed in MC1 receptor positive organ so that after 4 h the tumor uptake was 4.51 ± 0.11 % ID/g. Predominant renal excretion pathway with a highest accumulation of activity in tumor was observed for this radiopeptide. Obtained results show that the new designed labeled peptide conjugate can be a suitable candidate for diagnosis of metastatic melanomas.

Evaluation of (99m)Tc-TRODAT-1 SPECT in the diagnosis of Parkinson's disease versus other progressive movement disorders.

OBJECTIVE: Parkinson disease (PD), parkinsonian syndromes (PS) and essential tremor (ET) are different types of movement disorders which share some symptoms resulting in a difficulty of certain diagnosis. This study was conducted to determine the value of (99m)Tc-TRODAT-1 scan to differentiate PD from ET and other PS cases. METHODS: Totally, 75 patients were studied including 29 PD, 6 possible PD, 22 ET and 18 PS cases. A dual-head SPECT-CT was used to perform basal ganglia (BG) imaging following administration of (99m)Tc-TRODAT-1. The BG uptake values were normalized to whole brain and occipital activity. All patients were followed for 2-22 months to reach a certain diagnosis. RESULTS: Patients with ET and drug-induced parkinsonism show significantly higher normalized BG uptake as compared to the other subgroups; however, no significant difference was noted between PD and PS patients. The sensitivity and specificity of the findings for the differentiation between patients with the disease associated versus not associated with BG dysfunction were 80 and 83.3%, respectively. A predictive positive value of 82.6% was obtained using an additive scaling index defined as asymmetry and unevenness of uptake in putamen and/or caudate contralateral to the dominant side of current symptoms. CONCLUSIONS: (99m)Tc-TRODAT-1 scan is an appropriate method to differentiate PD or PS versus ET. A combination of scan pattern including asymmetry of BG uptake and unevenness of activity in caudate and putamen along with the side of dominant symptoms may be valuable for the differentiation of Parkinson's disease from the other parkinsonian syndromes.

Microleakage Evaluation at Implant-Abutment Interface Using Radiotracer Technique.

OBJECTIVES: Microbial leakage through the implant-abutment (I-A) interface results in bacterial colonization in two-piece implants. The aim of this study was to compare microleakage rates in three types of Replace abutments namely Snappy, GoldAdapt, and customized ceramic using radiotracing. MATERIALS AND METHODS: Three groups, one for each abutment type, of five implants and one positive and one negative control were considered (a total of 17 regular body implants). A torque of 35 N/cm was applied to the abutments. The samples were immersed in thallium 201 radioisotope solution for 24 hours to let the radiotracers leak through the I-A interface. Then, gamma photons received from the radiotracers were counted using a gamma counter device. In the next phase, cyclic fatigue loading process was applied followed by the same steps of immersion in the radioactive solution and photon counting. RESULTS: Rate of microleakage significantly increased (P≤0.05) in all three types of abutments (i.e. Snappy, GoldAdapt, and ceramic) after cyclic loading. No statistically significant differences were observed between abutment types after cyclic loading. CONCLUSIONS: Microleakage significantly increases after cyclic loading in all three Replace abutments (GoldAdapt, Snappy, ceramic). Lowest microleakage before and after cyclic loading was observed in GoldAdapt followed by Snappy and ceramic.