US-guided percutaneous ablation of thyroid nodules with 177LU-MAA (LUTMA) - Feasibility study.

PURPOSE: The main purpose is to evaluate the safety, and efficacy of 177Lutetium labeled macroaggregated albumin (LUTMA) ablation of thyroid nodules. MATERIALS AND METHODS: Patients with confirmed benign nodules who were not candidate or did not accept surgery were enrolled. Under ultrasonography (USG) guidance, LUTMA which was produced in our department, was administered into the nodules. Nodule volumes were assessed via USG before the injection and at 1-week, 1-month, and 3-months post-treatment. We calculated the volume reduction rates (VRRs) for these intervals. To detect extranodular activity leakage, patients underwent SPECT/CT imaging at one hour, 24 h, and one week post-injection. RESULTS: Fifteen patients (male: 12, female: 3) with benign thyroid nodules were eligible to join this study. These nodules were categorized as cystic (n = 9), solid (n = 3), or mixed (n = 3). Median nodules volume was 6.59 ml (range: 0.56-55 ml). Predicted absorbed dosee to the nodules varied between 10-1036 Gy. The VRRs at 3 months was 85% for all nodule types with gradual increases over time: 0%-92%, 20%-97%, and 28%-98% at 1 week, 1 month, and 3-months, respectively. The median VRR of cystic nodules was 89% (range: 81%-98%) at 3-months. It is significantly higher than solid ones (P = .009). None of the patients experienced adverse reactions or discomfort during the injection or follow-up. CONCLUSION: LUTMA treatment significantly reduces the volume of benign thyroid nodules, offering relief from disease-associated symptoms and cosmetic concerns. It emerges as a promising alternative to surgical and other local treatments for benign thyroid nodule ablation. CLINICAL SIGNIFICATION: LUTMA is a novel theranostic radiopharmaceutical which is promising in local ablative treatment of benign thyroid nodules.

89Zr-leukocyte labelling for cell trafficking: in vitro and preclinical investigations.

BACKGROUND: The non-invasive imaging of leukocyte trafficking to assess inflammatory areas and monitor immunotherapy is currently generating great interest. There is a need to develop more robust cell labelling and imaging approaches to track living cells. Positron emission tomography (PET), a highly sensitive molecular imaging technique, allows precise signals to be produced from radiolabelled moieties. Here, we developed a novel leukocyte labelling approach with the PET radioisotope zirconium-89 (89Zr, half-life of 78.4 h). Experiments were carried out using human leukocytes, freshly isolated from whole human blood. RESULTS: The 89Zr-leukocyte labelling efficiency ranged from 46 to 87% after 30-60 min. Radioactivity concentrations of labelled cells were up to 0.28 MBq/1 million cells. Systemically administered 89Zr-labelled leukocytes produced high-contrast murine PET images at 1 h-5 days post injection. Murine biodistribution data showed that cells primarily distributed to the lung, liver, and spleen at 1 h post injection, and are then gradually trafficked to liver and spleen over 5 days. Histological analysis demonstrated that exogenously 89Zr-labelled human leukocytes were present in the lung, liver, and spleen at 1 h post injection. However, intravenously injected free [89Zr]Zr4+ ion showed retention only in the bone with no radioactivity in the lung at 5 days post injection, which implied good stability of radiolabelled leukocytes in vivo. CONCLUSIONS: Our study presents a stable and generic radiolabelling technique to track leukocytes with PET imaging and shows great potential for further applications in inflammatory cell and other types of cell trafficking studies.

Is there any additional benefit of 68Ga-PSMA PET on radiotherapy target volume definition in patients with glioblastoma?

OBJECTIVE: To investigate the contribution of 68Gallium (68Ga)-PSMA (prostate-specific membrane antigen) positron emission tomography (PET) in defining radiotherapy (RT) target volume for glioblastoma and to compare the target volumes defined by Magnetic Resonance Imaging (MRI). METHODS: RT planning Computed Tomography (CT) images were fused separately with pre-operative MRI and PET/MRI images of 10 glioblastoma patients, retrospectively. The contrast-enhanced area in T1 weighted MRI was contoured as gross tumor volume (GTV) and clinical target volume (CTV1) was obtained by including the cavity and T2/FLAIR hyperintense areas after giving a margin of 2 cm to the GTV. 68Ga-PSMA uptake area was contoured as biological tumor volume (BTV) and CTV2 was obtained with a margin of 2 cm to BTV. Planning target volumes (PTVs) were created with the 3 mm added to the CTVs. Conformity index (CI), dice similarity coefficient (DSC) and overlap volume (OV) were calculated by obtaining the intersection and union volumes. Volumetric comparison, similarity and overlap analyzes were performed statistically by Wilcoxon signed rank and One sample t-test. RESULTS: The median GTV was 21,96 cc (1,04 - 82,04) and BTV was 25,58 cc (2,43 - 99,47). BTV was on average 47% larger than GTV which was statistically significant (p = 0.03). For GTV-BTV, CTV1-CTV2 and PTV1-PTV2; mean values of CI were 0,56, 0,76 and 0,76; DSC were 0,70, 0,86 and 0,86; OV were 0,88, 0,94 and 0,94, respectively. There was no significant difference on size and spatial similarity between CTV1 and CTV2, PTV1 and PTV2. CONCLUSION: Altough BTV was larger than GTV, this significance was lost while we gave the same CTV margin including the peripheral edema. It seems that it may help to improve defining non-enhancing tumor part and also recurrent tumor volume. ADVANCES IN KNOWLEDGE: Recent studies have focused on the role of 68Ga-PSMA PET in imaging of glial tumors. It has been observed that 68Ga-PSMA PET can clearly define the tumor borders and it can be beneficial in target volume delineation, especially in reirradiation of recurrent tumors.

A case of hepatic focal nodular hyperplasia mimicking hepatocellular carcinoma identified on gallium-68-prostate-specific membrane antigen positron emission tomography/computed tomography.

Prostate-specific membrane antigen (PSMA) is a glycosylated type-II transmembrane protein highly expressed in individual tumor cells. Lesions with PSMA expression in the liver are commonly reported as prostate cancer metastasis or hepatocellular cancer previously. This is the first case reported as hepatic focal nodular hyperplasia, mimicking hepatocellular carcinoma with imaging features. This patient, having a lesion that has been enlarged from 2.0 cm to 2.5 cm in 3 months, was referred to our department for restaging by gallium-68 PSMA (68Ga-PSMA) positron emission tomography/computed tomography (PET/CT). The CT scan showed a focal segment VI hypodensity, which was significantly PSMA-avid. Consequently, its biopsy resulted as focal nodular hyperplasia in liver. His follow-up 68Ga-PSMA PET/CT ultimately revealed a mass lesion of 8 cm of axial diameter.

Transient minimal hydronephrosis on contralateral kidney in infants with unilateral hydronephrosis: Is it an early sign of worsening of the affected kidney?

Background/aim: The criteria for surgical management of ureteropelvic junction obstruction are not well-defined, and there is a risk for loss of renal function before the operation. In this context, certain changes in contralateral kidney had been investigated in order to increase the sensitivity of diagnosis. In this study, we aimed to investigate whether contralateral transient minimal hydronephrosis (CTMH) can be considered as an "early alarm" sign for worsening of the affected kidney in infants with hydronephrosis. Materials and methods: A total of 182 infants (92 surgically treated and 90 conservatively followed-up) with unilateral hydronephrosis were retrospectively analyzed. Ultrasonography and renal scan findings were evaluated. Correlation between the appearance of CTMH, contralateral compensatory hypertrophy (CCH) on ultrasonography, and prognosis of the affected kidney were evaluated. Results: Among the surgically treated patients, 18 (19.6%) patients developed CTMH on average 7 months (0­13 months) before surgery. Among these 18 patients with CTMH, 12 patients (66.6%) had loss of renal function preoperatively, while this ratio was 29.7% on their counterparts (p = 0049). CCH was observed in 31 (33.7%) individuals in surgically treated patient group including all 18 patients with CTMH, while none of the conservatively followed-up patients developed CCH and/or CTMH. In the multiple logistic regression analysis, among the variables investigated, CTMH was found as an independent predictor of the deterioration in the affected kidney and of the poor prognosis (p = 0.011 and p = 0.0004, respectively). Conclusion: In our study, among the variables investigated, CTMH was found as an independent predictor of the deterioration in the affected kidney and poor prognosis in infants followed-up with isolated unilateral hydronephrosis. Additionally, CTMH can be considered as an "early alarm" sign for worsening of the affected kidney and the need for surgical intervention.

68Ga PSMA PET/MR in the differentiation of low and high grade gliomas: Is 68Ga PSMA PET/MRI useful to detect brain gliomas?

BACKGROUND: Magnetic resonance imaging (MRI) is the most important imaging modality in the diagnosis and follow-up of glial brain tumors. OBJECTIVE: The aim of our study is to determine the correlation between tumor grade, determined with postoperative pathological examination, and standard uptake value (SUV), a semi-quantitative parameter, in patients who underwent imaging 68Ga-PSMA with using PET/MR. MATERIAL-METHOD: Thirty-five out of 38 patients' images whose pathology was consistent with glial tumor, 42 lesions from separate anatomic localizations or with higher activity uptake than the rest of the tumor were evaluated. SUV values measured on PET images and grade relationship were evaluated based on each lesion while mitosis, Ki-67 were evaluated for each patient. RESULTS: Grade, Ki-67, mitosis, necrosis and SUVmax/mean/peak were found statistically significant with moderate/high correlation. The parameter with the highest correlation coefficient was mitosis. (For SUVmax r = 0.64, p = 0). When Grade II and III were considered as the first group and IV as the second group, the cutoff values were found to be 2.3 for SUVmax, 0.21 for SUVmean and 0.63 for SUVpeak. In the diagnosis of HGG, PET's sensitivity is higher than MRI but no statistically difference was found between specificities. CONCLUSION: 68Ga PSMA PET imaging is found to be particularly useful in differentiating Grade IV glial tumors from other grades. This finding is thought to be important in the differentiation the relapse with postoperative tissue changes, which is an important problem in the follow-up.

Correlation of SUVmax and Apparent Diffusion Coefficient Values Detected by Ga-68 PSMA PET/MRI in Primary Prostate Lesions and Their Significance in Lymph Node Metastasis: Preliminary Results of an On-going Study

Objectives: Gallium-68 (Ga-68) prostate specific membrane antigen (PSMA) positron emission tomography (PET) has been shown to be more accurate than multiparametric prostate magnetic resonance imaging (MRI) in detection of primary prostate lesions. Using hybrid PET/MRI we aim to detect the correlation between SUVmax and apparent diffusion coefficient (ADC) in primary prostate lesions and to assess their prognostic value in detection of lymph node (LN) metastasis. Methods: Twenty-six patients, who were diagnosed as having prostate cancer with biopsy and underwent Ga-68 PSMA PET/MRI together with biparametric prostate MRI (bpMRI) were included. SUVmax, SUVmean and ADC were recorded for index lesions drawing a region of interest (ROI) of 1 cm2 around the pixel with the highest SUVmax (ROI-1) and another ROI following borders of prostate tumor detected by bpMRI (ROI-2). Presence of LN metastasis was recorded according to PSMA PET/MRI Results: SUVmax was inversely correlated with ADC (ROI-1: p=0.010; ROI-2: p=0.017 for b=800). SUVmax and SUVmeans were both higher in patients with LN metastasis and ADC was lower in patients with LN metastasis for ROI-1. SUVmax cut-off value of 19.8 for ROI-1 and 20.9 for ROI-2 had sensitivity and specificity of 77.8% and 76.5%, respectively for detection of LN metastasis, whereas ADC (b=800) cut-off value of 0.92x10-3 mm2/s had sensitivity and specificity of 87.5% and 76.5%, respectively. SUVmax/ADC (b=800) ratio increased the sensitivity and specificity to 100% and 82.4%, respectively. Conclusion: SUV and ADC values are inversely correlated in primary prostate lesions and the combined use of both values increases the diagnostic accuracy of hybrid PET/MRI in the detection of primary prostate lesions.

Usefulness of 18F-FDG PET/CT in Cutaneous Melanoma Patients with Negative Sentinel Lymph Nodes and High Clark Levels.

OBJECTIVE: We investigated the utility of PET/CT in cutaneous melanoma (CM) patients with pathological negative sentinel lymph nodes (SLN), within the first year. METHODS: The results of PET/CTs and SLN biopsy (SLNB) in 65 patients (39 male and 26 female, mean age 53.8) with a PET/CT in the first postoperative year were evaluated. Within this cohort, the utility of early PET/CT imaging was assessed in patients with negative SLNB. McNemar test was used to compare PET/CT findings with SLNB results. RESULTS: Out of 43 patients with pathologically positive SLNs, 23 patients (53.5%) had positive and 20 patients (46.5%) had negative findings on PET/CT within the first postoperative year. On the other hand, PET/CT results of 22 patients with negative SLNBs were found to be negative in 19 patients (86.4%) and positive in 3 patients (13.6%). For the patients with negative SLNB results, the detection rate of distant metastasis with PET/CT was significantly lower (p<0.001) than that in patients with positive SLNBs. CONCLUSION: Our results showed that 18F-FDG PET/CT will most likely (86.4%) be negative during the first postoperative year in patients with a negative SLNB. Therefore, it is concluded that this modality would not provide any significant clinical contribution within this time frame.

Thoracic splenosis after a gunshot: diffusion-weighted MRI findings.

BACKGROUND: Intrathoracic splenosis is a rare condition resulting from concomitant rupture of the spleen and left hemidiaphragm after a traumatic event involving the spleen and the diaphragma and is defined as autotransplantation of splenic tissue in thorax. CASE REPORT: The aim of this study was to present a case report of a combined intrathoracic and subcutaneous splenosis in a patient 19 years after penetrating trauma. She has left dorsal side pain and routine chest roentgenogram shows pleural nodular masses. The patient was referred to us for radiologic work up. CONCLUSIONS: The MRI scans revealed the intrathoracic and subcutan masses as mainly hypointense on T1-weighted images and hyperintense on T2-weighted images and significant restriction in diffusion-weighted images. Scintigraphy revealed abnormal hot spots in subcutaneous tissue and diaphragmatic pleura of the left hemithorax.