Glioblastoma Multiforme Recurrence: An Exploratory Study of (18)F FPPRGD2 PET/CT

PURPOSE

To prospectively evaluate fluorine 18 ((18)F) 2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) (FPPRGD2) positron emission tomography (PET) in patients with glioblastoma multiforme (GBM).

MATERIALS AND METHODS

The institutional review board approved this HIPAA-compliant protocol. Written informed consent was obtained from each patient. (18)F FPPRGD2 uptake was measured semiquantitatively in the form of maximum standardized uptake values (SUV(max)) and uptake volumes before and after treatment with bevacizumab. Vital signs and laboratory results were collected before, during, and after the examinations. A nonparametric version of multivariate analysis of variance was used to assess safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare SUV(max).

RESULTS

A total of 17 participants (eight men, nine women; age range, 25-65 years) were enrolled prospectively. (18)F FPPRGD2 PET/computed tomography (CT), (18)F fluorodeoxyglucose (FDG) PET/CT, and brain magnetic resonance (MR) imaging were performed within 3 weeks, prior to the start of bevacizumab therapy. In eight of the 17 patients (47%), (18)F FPPRGD2 PET/CT was repeated 1 week after the start of bevacizumab therapy; six patients (35%) underwent (18)F FPPRGD2 PET/CT a third time 6 weeks after starting bevacizumab therapy. There were no changes in vital signs, electrocardiographic findings, or laboratory values that qualified as adverse events. One patient (6%) had recurrent GBM identified only on (18)F FPPRGD2 PET images, and subsequent MR images enabled confirmation of recurrence. Of the 17 patients, 14 (82%) had recurrent GBM identified on (18)F FPPRGD2 PET and brain MR images, while (18)F FDG PET enabled identification of recurrence in 13 (76%) patients. Two patients (12%) had no recurrent GBM.

CONCLUSION

(18)F FPPRGD2 is a safe PET radiopharmaceutical that has increased uptake in GBM lesions. Larger cohorts are required to confirm these preliminary findings.

Combined 18F-fluoride and 18F-FDG PET/CT scanning for evaluation of malignancy: results of an international multicenter trial

(18)F-FDG PET/CT is used in a variety of cancers, but because of variable rates of glucose metabolism, not all cancers are reliably identified. (18)F(-) PET/CT allows for the acquisition of highly sensitive and specific images of the skeleton. We prospectively evaluated combined (18)F(-)/(18)F-FDG as a single PET/CT examination for evaluation of cancer patients and compared it with separate (18)F(-) PET/CT and (18)F-FDG PET/CT scans.

METHODS

One hundred fifteen participants with cancer were prospectively enrolled in an international multicenter trial evaluating (18)F(-) PET/CT, (18)F-FDG PET/CT, and combined (18)F(-)/(18)F-FDG PET/CT. The 3 PET/CT scans were performed sequentially within 4 wk of one another for each patient.

RESULTS

(18)F(-)/(18)F-FDG PET/CT allowed for accurate interpretation of radiotracer uptake outside the skeleton, with findings similar to those of (18)F-FDG PET/CT. In 19 participants, skeletal disease was more extensive on (18)F(-) PET/CT and (18)F(-)/(18)F-FDG PET/CT than on (18)F-FDG PET/CT. In another 29 participants, (18)F(-) PET/CT and (18)F(-)/(18)F-FDG PET/CT showed osseous metastases where (18)F-FDG PET/CT was negative. The extent of skeletal lesions was similar in 18 participants on all 3 scans.

CONCLUSION

This trial demonstrated that combined (18)F(-)/(18)F-FDG PET/CT shows promising results when compared with separate (18)F(-) PET/CT and (18)F-FDG PET/CT for evaluation of cancer patients. This result opens the possibility for improved patient care and reduction in health-care costs, as will be further evaluated in future trials.

Proposal for a Quantitative 18F-FDG PET/CT Metabolic Parameter to Assess the Intensity of Bone Involvement in Multiple Myeloma

Many efforts have been made to standardize the interpretation of ¹⁸F-FDG PET/CT in multiple myeloma (MM) with qualitative visual analysis or with quantitative metabolic parameters using various methods for lesion segmentation of PET images. The aim of this study was to propose a quantitative method for bone and bone marrow evaluation of ¹⁸F-FDG PET/CT considering the extent and intensity of bone ¹⁸F-FDG uptake: Intensity of Bone Involvement (IBI). Whole body ¹⁸F-FDG PET/CT of 59 consecutive MM patients were evaluated. Compact bone tissue was segmented in PET images using a global threshold for HU of the registered CT image. A whole skeleton mask was created and the percentage of its volume with ¹⁸F-FDG uptake above hepatic uptake was calculated (Percentage of Bone Involvement - PBI). IBI was defined by multiplying PBI by mean SUV above hepatic uptake. IBI was compared with visual analysis performed by two experienced nuclear medicine physicians. IBI calculation was feasible in all images (range:0.00–1.35). Visual analysis categorized PET exams into three groups (negative/mild, moderate and marked bone involvement), that had different ranges of IBI (multi comparison analysis, p < 0.0001). There was an inverse correlation between the patients’ hemoglobin values and IBI (r = −0.248;p = 0.02). IBI score is an objective measure of bone and bone marrow involvement in MM, allowing the categorization of patients in different degrees of aggressiveness of the bone disease. The next step is to validate IBI in a larger group of patients, before and after treatment and in a multicentre setting.

Classification of proliferative diabetic retinopathy

Using panretinal fluorescein angiography, three patterns (A, B, C) of capillary nonperfusion were identified in 308 eyes with proliferative diabetic retinopathy. Statistical analysis showed that there was a significant association with different retinal complications and clinical parameters. Pattern A (83.7%: midperipheral location of capillary nonperfusion) occurs in type I and II diabetes and is associated with early retinal neovascularization and focal macular edema. Pattern B (8.1%: capillary exclusions disseminated on the whole retina) is typical of young type-I diabetics and is complicated by early disc new vessels and ischemic maculopathy. Pattern C (8.1%: capillary nonperfusion confined to the peripheral retina) is observed in type-I diabetic females and associated with multiple, retinal new vessels, without maculopathy. This study also demonstrated that eyes with pattern B retinal ischemia respond less well to laser treatment than eyes with other pattern types. Various pathogenetic factors could lead to these three distinct types of proliferative diabetic retinopathy.

Clinical Evaluation of (4S)-4-(3-[18F]Fluoropropyl)-L-glutamate (18F-FSPG) for PET/CT Imaging in Patients with Newly Diagnosed and Recurrent Prostate Cancer

PURPOSE

(4S)-4-(3-[¹⁸F]Fluoropropyl)-L-glutamic acid (¹⁸F-FSPG) is a radiopharmaceutical for PET imaging of system x_C ^- activity, which can be upregulated in prostate cancer. We present data on the first evaluation of patients with newly diagnosed or recurrent prostate cancer with this radiopharmaceutical.

EXPERIMENTAL DESIGN

Ten patients with primary and 10 patients with recurrent prostate cancer were enrolled in this prospective multicenter study. After injection of 300 MBq of ¹⁸F-FSPG, three whole-body PET/CT scans were obtained. Visual analysis was compared with step-section histopathology when available as well as other imaging studies and clinical outcomes. Metabolic parameters were measured semiquantitatively. Expression levels of xCT and CD44 were evaluated by IHC for patients with available tissue samples.

RESULTS

¹⁸F-FSPG PET showed high tumor-to-background ratios with a relatively high tumor detection rate on a per-patient (89%) and per-lobe (87%) basis. The sensitivity was slightly higher with imaging at 105 minutes in comparison with 60 minutes. The maximum standardized uptake values (SUV_max) for cancer was significantly higher than both normal (P < 0.005) and benign pathology (P = 0.011), while there was no significant difference between normal and benign pathology (P = 0.120). In the setting of recurrence, agreement with standard imaging was demonstrated in 7 of 9 patients (78%) and 13 of 18 lesions (72%), and revealed true local recurrence in a discordant case. ¹⁸F-FSPG accumulation showed moderate correlation with CD44 expression.

CONCLUSIONS

¹⁸F-FSPG is a promising tumor imaging agent for PET that seems to have favorable biodistribution and high cancer detection rate in patients with prostate cancer. Further studies are warranted to determine the diagnostic value for both initial staging and recurrence, and how it compares with other investigational radiotracers and conventional imaging modalities.

Characterization of Physiologic (18)F FSPG Uptake in Healthy Volunteers

Purpose To evaluate the normal biodistribution and kinetics of (S)-4-(3-[18F]fluoropropyl)-l-glutamic acid ((18)F FSPG) in healthy volunteers and to compare (18)F FSPG mean and maximum standardized uptake values (SUVmean and SUVmax, respectively) with those of (18)F fluorodeoxyglucose (FDG) across a variety of organs. Materials and Methods This protocol was reviewed and approved by all appropriate regulatory authorities. An 8-mCi (±10%) dose of (18)F FSPG was given to five subjects (three women, two men), and seven whole-body positron emission tomography (PET) scans were performed 5, 10, 20, 30, 45, 150, and 240 minutes after injection. Regions of interest were analyzed on the resultant (18)F FSPG images to evaluate the kinetics of this radiotracer. The images obtained 45 minutes after injection were used to measure SUVmean and SUVmax in additional regions of the body. These values were compared with similar values obtained with (18)F FDG PET published previously. Descriptive statistics, including average and standard deviation across the five subjects, were used. (18)F FSPG SUVmean and SUVmax were compared. Results On the (18)F FSPG images obtained 45 minutes after injection, there was only low-grade background activity in the majority of analyzed regions. Prominent activity was seen throughout the pancreas. Clearance of the radiotracer through the kidneys and collection in the bladder also were seen. SUV quantification shows notable differences between (18)F FSPG and (18)F FDG in the pancreas ((18)F FSPG SUVmean, 8.2; (18)F FDG SUVmean, 1.3), stomach ((18)F FSPG SUVmax, 3.6; (18)F FDG SUVmax, 1.6), and brain ((18)F FSPG SUVmean, 0.08; (18)F FDG SUVmean, 7.8). The kinetic data showed rapid clearance of the radiotracer from the blood pool and most organs, except the pancreas. Conclusion (18)F FSPG is a PET radiopharmaceutical characterized by rapid clearance from most healthy tissues, except the pancreas and kidneys. A consistent biodistribution pattern was observed with low background uptake. The physiologic uptake of this new radiotracer throughout the body is described in more detail, which is important for improved interpretative accuracy and understanding potential clinical applications. (©) RSNA, 2016.

Initial evaluation of (4S)-4-(3-[18F]fluoropropyl)-L-glutamate (FSPG) PET/CT imaging in patients with head and neck cancer, colorectal cancer, or non-Hodgkin lymphoma

Purpose

(4S)-4-(3-[¹⁸F]Fluoropropyl)-l-glutamic acid ([¹⁸F]FSPG) measures system x_C⁻ transporter activity and shows promise for oncologic imaging. We present data on tumor uptake of this radiopharmaceutical in human subjects with head and neck cancer (HNC), colorectal cancer (CRC), and non-Hodgkin lymphoma (NHL).

Methods

A total of 15 subjects with HNC (n = 5), CRC (n = 5), or NHL (n = 5) were recruited (mean age 66.2 years, range 44–87 years). 301.4 ± 28.1 MBq (8.1 ± 0.8 mCi) of [¹⁸F]FSPG was given intravenously to each subject, and 3 PET/CT scans were obtained 0–2 h post-injection. All subjects also had a positive [¹⁸F]FDG PET/CT scan within 1 month prior to the [¹⁸F]FSPG PET scan. Semi-quantitative and visual comparisons of the [¹⁸F]FSPG and [¹⁸F]FDG scans were performed.

Results

[¹⁸F]FSPG showed strong uptake in all but one HNC subject. The lack of surrounding brain uptake facilitated tumor delineation in the HNC patients. [¹⁸F]FSPG also showed tumor uptake in all CRC subjects, but variable uptake in the NHL subjects. While the absolute [¹⁸F]FDG SUV values were comparable or higher than [¹⁸F]FSPG, the tumor-to-background SUV ratios were greater with [¹⁸F]FSPG than [¹⁸F]FDG.

Conclusions

[¹⁸F]FSPG PET/CT showed promising results across 15 subjects with 3 different cancer types. Concordant visualization was mostly observed between [¹⁸F]FSPG and [¹⁸F]FDG PET/CT images, with some inter- and intra-individual uptake variability potentially reflecting differences in tumor biology. The tumor-to-background ratios were greater with [¹⁸F]FSPG than [¹⁸F]FDG in the cancer types evaluated. Future studies based on larger numbers of subjects and those with a wider array of primary and recurrent or metastatic tumors are planned to further evaluate the utility of this novel tracer.

Adipose tissue radiodensity: A new prognostic biomarker in people with multiple myeloma

OBJECTIVES

Standard prognostic markers based on individual characteristics of individuals with multiple myeloma (MM) remain scarce. Body-composition features have often been associated with survival outcomes in different cancers. However, the association of adipose tissue radiodensity with MM prognosis has not yet, to our knowledge, been explored.

METHODS

Computed tomography at the third lumbar vertebra was used for body-composition analysis, including adipose tissue radiodensity, in 91 people with MM. Additionally, fludeoxyglucose F 18 (18F-FDG) positron emission tomography was used to assess adipose tissue 18F-FDG uptake. Proinflammatory cytokine and adipokine levels were measured.

RESULTS

Event-free survival and overall survival were both shorter in participants with high subcutaneous adipose tissue (SAT) radiodensity. Those in the highest SAT radiodensity tertile had an independently higher risk for both overall survival (hazard ratio, 4.55; 95% confidence interval, 1.26-16.44; Ptrend = 0.036) and event-free survival (hazard ratio, 3.08; 95% confidence interval, 1.02-9.27; Ptrend = 0.035). Importantly, higher SAT radiodensity was significantly correlated with increased 18F-FDG adipose tissue uptake and proinflammatory cytokine (tumor necrosis factor and interleukin-6) levels, and with decreased leptin levels.

CONCLUSIONS

SAT radiodensity may serve as a biomarker to predict host-related metabolic and proinflammatory milieu, which ultimately correlates with MM prognosis.

Treatment of uncomplicated cases of rhegmatogenous retinal detachment with an expanding gas bubble

We reviewed 55 consecutive cases of rhegmatogenous retinal detachment treated with pneumatic retinopexy as a primary procedure and followed up for a minimum of 1 year. 40 eyes were phakic, 11 aphakic and 4 pseudophakic. 0.6 ml of sulfur hexafluoride were injected into 42 eyes, while 0.3 ml of perfluoropropane were introduced into 13. Transconjunctival cryotherapy was performed in 51 eyes, while light coagulation was used as retinopexy after the retina was reattached in the remaining 4 cases. Of the 55 eyes undergoing treatment, 46 (83.6%) retinas were reattached with one operation. The benefits, complications and disadvantages of the procedure are reported.

Validation of the Semiautomatic Quantification of 18F-Fluoride PET/CT Whole-Body Skeletal Tumor Burden

Our purpose was to validate a semiautomatic quantification of the skeletal tumor burden on ¹⁸F-fluoride PET/CT using manual quantification as a reference. Methods: We quantified 51 ¹⁸F-fluoride PET/CT examinations performed on female breast cancer patients. Clinical information (age; time of disease presentation; presence of visceral metastases; and time to death, progression, or a bone event) was recorded. The total volume of ¹⁸F-fluoride-avid skeletal metastases and the total activity of ¹⁸F-fluoride-avid metastases were calculated manually and semiautomatically. Results: Manual and semiautomatic metrics correlated strongly (P < 0.0001; 95% confidence interval, 0.9300-0.9769). On multivariable analysis, the semiautomatic measures of total activity for ¹⁸F-fluoride-avid metastasis correlated significantly with overall survival (P = 0.0001) and progression-free survival (P = 0.0006). Approximate times for calculating skeletal tumor burden (semiautomatic vs. manual) were, respectively, 30 s versus 321 s in patients with fewer than 5 metastases, 120 s versus 640 s in patients with 5-10 metastases, and 240 s versus 1207s in patients with more than 10 metastases. Conclusion: Semiautomatic quantification of whole-body ¹⁸F-fluoride PET/CT skeletal tumor burden can replace manual quantification in breast cancer patients and is a strong independent biomarker of prognosis.

Visceral adipose tissue glucose uptake is linked to prognosis in multiple myeloma patients: An exploratory study

BACKGROUND & AIMS

The use of computerized tomography to opportunistically assess body composition has highlighted abnormalities such as low muscle mass and high adiposity may be hidden conditions in cancer patients. However, the role of skeletal muscle (SM), subcutaneous (SAT) and visceral (VAT) adipose tissue glucose uptake measured by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)-CT on patient prognostication is unclear.

METHODS

Patients with multiple myeloma (MM) with satisfactory image frame for assessing body composition and for semi-quantification of SM, SAT and VAT glucose uptakes were included. Plasmatic pro-inflammatory cytokine and adipokine levels were measured.

RESULTS

High VAT mean standardized uptake value (SUV) at baseline was associated with shorter event-free survival (EFS) (hazard ratio [HR]: 7.89; 95% confidence interval [CI], 1.58-39.30; P = 0.012) and overall survival (OS) (HR, 15.24; 95% CI, 2.69-86.30; P = 0.002) among patients with newly diagnosed MM, even after adjustment for covariates. The highest tertile of VAT SUV was significantly correlated with worse MM-EFS (HR for the highest vs the lowest tertile 3.71; 95% CI, 1.22-10.56; Ptrend = 0.035) and mortality (HR, 4.41; 95% CI, 1.28-12.77; Ptrend = 0.019). Notably, patients with higher VAT SUV presented with lower VAT area, VAT index, higher SAT SUV, and higher number of individuals with visceral obesity (all P < 0.01). Additionally, we found a negative correlation between VAT mean SUV with leptin (R2 = 0.20, P = 0.003); no correlations were detected between VAT mean SUV and resistin, tumor necrosis factor (TNF) or interleukin (IL)-6.

CONCLUSIONS

Functional VAT activity estimated by 18F-FDG PET-CT is a relevant prognostic factor in MM patients, specifically, a higher VAT SUV might be an early biomarker of cancer cachexia in these patients.

99mTc-sestamibi SPECT/CT and 18F-FDG-PET/CT have similar performance but different imaging patterns in newly diagnosed multiple myeloma

PURPOSE

F-fluorodeoxiglucose (F-FDG)-PET/CT has been widely used to evaluate multiple myeloma. Tc-sestamibi (MIBI) scintigraphy has also been proposed for assessing multiple myeloma, but its use with state-of-the-art single-photon emission computed tomography/computed tomography (SPECT/CT) technology has not been fully evaluated.This study aimed to compare these two imaging modalities in multiple myeloma staging.

MATERIALS AND METHODS

Sixty-two patients with recently diagnosed multiple myeloma were submitted to whole-body F-FDG-PET/CT and whole-body MIBI scans plus SPECT/CT of the chest and abdomen/pelvis. Number of focal lesions, contiguous soft tissue involvement (CSTI), extramedullary lesions (EMLs) and diffuse bone marrow (BM) involvement were recorded.

RESULTS

PET/CT was positive in 59 patients (95%) and MIBI SPECT/CT in 58 (93%) (P = 0.69). MIBI detected more diffuse bone marrow involvement than PET/CT (respectively 78 vs. 58% of the patients), while PET/CT demonstrated more focal lesions than MIBI SPECT/CT (81 vs. 54% of the patients) (P = 0.002). PET/CT detected EMLs in four subjects and MIBI in one subject. CSTI was found in 28 (45%) and 23 (37%) patients on PET/CT and MIBI images, respectively (P = 0.36). Three patients with lytic lesions and no FDG uptake were MIBI positive, and two subjects with lytic lesions without MIBI uptake were FDG positive.

CONCLUSION

MIBI SPECT/CT performs similarly to F-FDG-PET/CT in identifying sites of active disease in multiple myeloma staging. MIBI is more efficient than FDG for detecting the diffuse involvement of bone marrow but less efficient for detecting focal lesions. Some patients presented a 'mismatch' pattern of FDG/MIBI uptake.

Influence of bladder fullness on the detection of urinary tract obstruction by dynamic renal scintigraphy

Objective

To investigate the influence of bladder fullness on the diagnosis of urinary tract obstruction during dynamic renal scintigraphy with a diuretic stimulator.

Materials and methods

We studied 82 kidneys in 82 patients submitted to dynamic renal scintigraphy with a diuretic stimulator. We compared the proportional elimination of the radiopharmaceutical ^99mTc-DTPA from the kidneys before and after bladder emptying in post-diuretic images, classifying each image as representing an obstructed, indeterminate, or unobstructed kidney.

Results

The overall elimination of ^99mTc-DTPA from the kidneys was 10.4% greater after bladder emptying than before. When the analysis was performed with a full bladder, we classified 40 kidneys as obstructed, 16 as indeterminate, and 26 as unobstructed. When the 40 kidneys classified as obstructed were analyzed after voiding, 11 were reclassified as indeterminate and 3 were reclassified as unobstructed. Of the 16 kidneys classified as indeterminate on the full-bladder images, 13 were reclassified as unobstructed after voiding.

Conclusion

In dynamic renal scintigraphy with a diuretic stimulator, it is important to obtain images after voiding, in order to perform a reliable analysis of the proportional excretion of ^99mTc-DTPA from the kidneys, avoiding possible false-positive results for urinary tract obstruction.

Intensity of bone involvement: a quantitative 18F-FDG PET/CT evaluation for monitoring outcome of multiple myeloma

PURPOSE

The parameter intensity of bone involvement (IBI) was recently proposed to quantitatively assess patients with multiple myeloma using 18F-fluorodeoxyglucose-PET combined with computed tomography (18F-FDG PET/CT) images. Here, we aimed to calculate IBI variation (ΔIBI) between two consecutive PET/CT of the same patient and verified its relationship with a subjective visual analysis of the images and with clinical outcome.

METHODS

Consecutive whole-body 18F-FDG PET/CT performed to assess the outcomes of 29 patients diagnosed with multiple myeloma were retrospectively evaluated. ΔIBI was calculated after bone segmentation, using liver standardized uptake value as a threshold to determine metabolically active volumes in the skeleton. For each pair of consecutive PET/CTs, two nuclear medicine physicians classified visually the most recent image as PET-remission, PET-progression or PET-stable when compared to the previous examination.

RESULTS

The lowest ΔIBI was -1.27 and the highest was 0.29. PET-remission was related to ΔIBI <0 (median = -0.10; -1.27 to +0.03), while PET-progression was related to ΔIBI >0 (median = 0.02; -0.07 to +0.29). ΔIBI around zero was found in images classified as PET-stable (median = 0.00; -0.08 to +0.06). Significant difference in ΔIBI was found between the three groups. Multivariate stepwise analysis showed that IBI value at diagnostic PET/CT, serum calcium and percentage of plasma cells in the bone marrow are independent prognostic factors.

CONCLUSION

Delta IBI provides quantitative data for variations of 18F-FDG uptake in the bone marrow during the follow-up of the patients. In addition, higher IBI values at diagnosis are associated with a higher risk of patient's death.

Ultrasonographic follow-up of patients with choroidal melanoma following conservative treatment

The authors assessed the regression of choroidal tumors, following irradiation treatment, by means of B scan sonography (Sonomed B 3000). Thirty-two patients were studied, 12 of whom underwent brachytherapy with 106Ru plaques and 20 of whom were treated with accelerated protons. After a follow-up period of 12 months, the following was observed: reduction of the thickness of the tumor (significantly greater in the tumors which underwent brachytherapy) and morphological and structural changes which consisted in a thinning of the tumor and an increased reflectivity.