Phantom study of SPECT/CT augmented reality for intraoperative localization of sentinel lymph nodes in head and neck melanoma

OBJECTIVE

To show that augmented reality (AR) visualization of single-photon emission computed tomography (SPECT)/computed tomography (CT) data in 3D can be used to accurately localize targets in the head and neck region.

MATERIALS AND METHODS

Eight head and neck styrofoam phantoms were painted with a mixture of radioactive solution (Tc-99m) detectable with a handheld gamma probe and fluorescent ink visible only under ultraviolet (UV) light to create 10-20 simulated lymph nodes on their surface. After obtaining SPECT/CT images of these phantoms, virtual renderings of the nodes were generated from the SPECT/CT data and displayed using a commercially available AR headset. For each of three physician evaluators, the time required to localize lymph node targets was recorded (1) using the gamma probe alone and (2) using the gamma probe while wearing the AR headset. In addition, the surface localization accuracy when using the AR headset was evaluated by measuring the misalignment between the locations visually marked by the evaluators and the ground truth locations identified using UV stimulation of the ink at the site of the nodes.

RESULTS

For all three evaluators, using the AR headset significantly reduced the time to detect targets (P = 0.012, respectively) compared to using the gamma probe alone. The average misalignment between the location marked by the evaluators and the ground truth location was 8.6 mm.

CONCLUSION

AR visualization of SPECT/CT data in 3D allows for accurate localization of targets in the head and neck region, and may reduce the localization time of targets.

Prognostic Value of Bone Marrow Metabolism on Pretreatment 18F-FDG PET/CT in Patients with Metastatic Melanoma Treated with Anti-PD-1 Therapy

Our purpose was to investigate the prognostic value of ¹⁸F-FDG PET/CT parameters in melanoma patients before beginning therapy with antibodies to the programmed cell death 1 receptor (anti-PD-1). Methods: Imaging parameters including SUV_max, metabolic tumor volume, and the ratio of bone marrow to liver SUV_mean (BLR) were measured from baseline PET/CT in 92 patients before the start of anti-PD-1 therapy. The association with survival and imaging parameters combined with clinical factors was evaluated. Clinical and laboratory data were compared between the high-BLR group (>median) and the low-BLR group (≤median). Results: Multivariate analyses demonstrated that BLR was an independent prognostic factor for progression-free and overall survival (P = 0.017 and P = 0.011, respectively). The high-BLR group had higher white blood cell counts and neutrophil counts and a higher level of C-reactive protein than the low-BLR group (P < 0.05). Conclusion: Patients with a high BLR were associated with poor progression-free and overall survival, potentially explained by evidence of systemic inflammation known to be associated with immunosuppression.

The Clinical Utility of 18F-Fluciclovine PET/CT in Biochemically Recurrent Prostate Cancer: an Academic Center Experience Post FDA Approval

PURPOSE

To evaluate the diagnostic performance and clinical utility of ¹⁸F-fluciclovine PET/CT in patients with biochemical recurrence (BCR) of prostate cancer (PC).

METHODS

¹⁸F-Fluciclovine scans of 165 consecutive men with BCR after primary definitive treatment with prostatectomy (n = 102) or radiotherapy (n = 63) were retrospectively evaluated. Seventy patients had concurrent imaging with at least one other conventional modality (CT (n = 31), MRI (n = 31), or bone scan (n = 26)). Findings from ¹⁸F-fluciclovine PET were compared with those from conventional imaging modalities. The positivity rate and impact of ¹⁸F-fluciclovine PET on patient management were recorded. In 33 patients who underwent at least one other PET imaging (¹⁸F-NaF PET/CT (n = 12), ⁶⁸Ga-PSMA11 PET/CT (n = 5), ¹⁸F-DCFPyL PET/CT (n = 20), and ⁶⁸Ga-RM2 PET/MRI (n = 5)), additional findings were evaluated.

RESULTS

The overall positivity rate of ¹⁸F-fluciclovine PET was 67 %, which, as expected, increased with higher prostate-specific antigen (PSA) levels (ng/ml): 15 % (PSA < 0.5), 50 % (0.5 ≤ PSA < 1), 56 % (1 ≤ PSA < 2), 68 % (2 ≤ PSA < 5), and 94 % (PSA ≥ 5), respectively. One hundred and two patients (62 %) had changes in clinical management based on ¹⁸F-fluciclovine PET findings. Twelve of these patients (12 %) had lesion localization on ¹⁸F-fluciclovine PET, despite negative conventional imaging. Treatment plans of 14 patients with negative ¹⁸F-fluciclovine PET were changed based on additional PET imaging with a different radiopharmaceutical.

CONCLUSION

¹⁸F-Fluciclovine PET/CT remains a useful diagnostic tool in the workup of patients with BCR PC, changing clinical management in 62 % of participants in our cohort.

Imaging Characteristics and Diagnostic Performance of 2-deoxy-2-[18F]fluoro-D-Glucose PET/CT for Melanoma Patients Who Demonstrate Hyperprogressive Disease When Treated with Immunotherapy

PURPOSE

We investigated the ability of baseline 2-deoxy-2-[¹⁸F]fluoro-D-glucose PET/CT parameters, acquired before the start of immunotherapy, to predict development of hyperprogressive disease (HPD) in melanoma patients. We also evaluated the diagnostic performances of ratios of baseline and first restaging PET/CT parameters to diagnose HPD without information of the tumor growth kinetic ratio (TGKR) that requires pre-baseline imaging before baseline imaging (3 timepoint imaging).

PROCEDURES

Seventy-six patients who underwent PET/CT before and approximately 3 months following initiation of immunotherapy were included. PET/CT parameters, including metabolic tumor volume (MTV) for all melanoma lesions and total measured tumor burden (TMTB) based on irRECIST, were measured from baseline PET/CT (MTV_base and TMTB_base) and first restaging PET/CT (MTV_post and TMTB_post). The ratios of MTV (MTV_post/MTV_base, MTVr) and TMTB (TMTB_post/TMTB_base, TMTBr) were calculated.

RESULTS

MTV_base of HPD patients (n = 9, TGKR ≥ 2) was larger than that of non-HPD (n = 67, TGKR < 2) patients (P < 0.05), and HPD patients demonstrated shorter median overall survival (7 vs. more than 60 months, P < 0.05). The area under the curve (AUC) of MTV_base (≥ 155.5 ml) to predict the risk of HPD was 0.703, with a sensitivity of 66.7 % and specificity of 81.2 %. The AUCs of MTVr (≥ 1.25) and TMTBr (≥ 1.27) to diagnose HPD without information of TGKR were 0.875 and 0.977 with both sensitivities of 100 %, and specificities of 79 % and 83.9 %, respectively.

CONCLUSIONS

Patients at high risk of developing HPD could not be accurately identified based on baseline PET/CT parameters. The ratios of baseline and first restaging PET/CT parameters may be helpful to diagnose HPD, when patients do not undergo pre-baseline imaging.

Prospective evaluation of 18F-DCFPyL PET/CT in biochemically recurrent prostate cancer: Analysis of lesion localization and distribution

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Background: 18F-DCFPyL, a promising PET agent targeting prostate specific membrane antigen (PSMA), is prospectively evaluated in a single academic center for detecting recurrent lesions in prostate cancer patients with biochemical recurrence (BCR). Methods: We prospectively enrolled 150 men (51-91 years old, mean ± SD: 70.3±7.5) with biochemical recurrence (PSA median 2.38 ng/mL, range 0.12 to 698.4) after primary definitive treatment with prostatectomy (65%), radiotherapy (35%) or both (19%). The 18F-DCFPyL positive lesions compatible with prostate cancer were evaluated by two independent readers. Impact of 18F-DCFPyL PET/CT on patient management was recorded from clinical chart review. Results: 18F-DCFPyL PET/CT had an overall positivity rate of 83% (125 scans), which increased with higher prostate specific antigen (PSA) levels (ng/mL): 63% (PSA < 0.5), 75% (0.5≤PSA < 1), 91% (1≤PSA < 2), 95% (2≤PSA < 5) and 98% (PSA≥5), respectively. In the cohort who underwent prostatectomy, 18F-DCFPyL PET/CT had higher positivity rate in patients with shorter PSA doubling time (PSAdt) (94% in PSAdt 0-3 months vs. 53% in PSAdt > 12 months, P< 0.01). No difference of 18F-DCFPyL positivity rate was observed in post-radiation patients with different PSAdt, nor were there differences between patients with low grade (Gleason 6) or higher-grade prostate cancer (Gleason 7-10). 20 patients (13%) had lesions in the prostate bed only and 41 patients (27%) had oligometastatic disease (1-3 lesions), making them candidates for locally targeted therapy. We identified a total of 1455 18F-DCFPyL positive lesions, including 51 lesions in the prostate bed, 271 pelvic and 463 extra-pelvic lymph nodes, approximately 585 osseous lesions, including 5 patients with diffuse osseous metastases, and 85 lesions in other organs (most commonly in the lungs). 91 out of 150 patients (61%) had change in treatment after 18F-DCFPyL PET and, most noticeably, 48 of these patients (32% total) had lesions only localized on 18F-DCFPyL PET/CT despite negative conventional imaging. Conclusions: 18F-DCFPyL PET/CT holds great potential to be a “one-stop shop” diagnostic tool in the work-up of BCR prostate cancer, with high (61%) impact on the management of these patients. Clinical trial information: NCT03501940 .

Prognostic value of volumetric PET parameters at early response evaluation in melanoma patients treated with immunotherapy

PURPOSE

The purpose of this study was to investigate the prognostic value of whole-body metabolic tumor volume (MTV) and other metabolic tumor parameters, obtained from baseline and first restaging ¹⁸F-FDG PET/CT scans in melanoma patients treated with immune checkpoint inhibitors (ICIs).

METHODS

Eighty-five consecutive melanoma patients (M, 57; F, 28) treated with ICIs who underwent PET/CT scans before and approximately 3 months after the start of immunotherapy were retrospectively enrolled. Metabolic tumor parameters including MTV for all melanoma lesions were measured on each scan. A Cox proportional hazards model was used for univariate and multivariate analyses of metabolic parameters combined with known clinical prognostic factors associated with overall survival (OS). Kaplan-Meier curves for patients dichotomized based on median values of imaging parameters were generated.

RESULTS

The median OS time in all patients was 45 months (95% CI 24-45 months). Univariate analysis demonstrated that MTV obtained from first restaging PET/CT scans (MTVpost) was the strongest prognostic factor for OS among PET/CT parameters (P < 0.0001). The median OS in patients with high MTVpost (≥ 23.44) was 16 months (95% CI 12-32 months) as compared with more than 60 months in patients with low MTVpost (< 23.44) (P = 0.0003). A multivariate model including PET/CT parameters and known clinical prognostic factors revealed that MTVpost and the presence of central nervous system lesions were independent prognostic factors for OS (P = 0.0004, 0.0167, respectively). One pseudoprogression case (1.2%) was seen in this population and classified into the high MTVpost group.

CONCLUSION

Whole-body metabolic tumor volume from PET scan acquired approximately 3 months following initiation of immunotherapy (MTVpost) is a strong prognostic indicator of OS in melanoma patients. Although the possibility of pseudoprogression must be considered whenever evaluating first restaging PET imaging, it only occurred in 1 patient in our cohort.

Single institution experience with peptide receptor radionuclide therapy (PRRT) in neuroendocrine tumors (NET)

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Background: Neuroendocrine tumors (NETs) are rare but increasing in incidence. The only curative treatment is surgery, which in many cases is not an option due to metastatic disease at diagnosis. The NETTER-1 study showed high efficacy and low toxicity of peptide receptor radionuclide therapy (PRRT) for midgut NETs. Here, we present our initial experience with PRRT in the treatment of patients with NET. Methods: Fifty-two patients (27 males and 25 females; 37 - 81 yo, mean ± SD: 61.8 ± 10.6 years) with documented progressive NET (25 pancreas, 17 small intestine, 1 coecum, 4 unknown primary, 3 paragangliomas, and 2 pheochromocytomas) were referred to undergo PRRT at our institution from July 2018 to September 2019. Laboratory tests were obtained at baseline, 1 week before each cycle and every 3 months following treatment. Progression-free survival (PFS), objective response rate (ORR) and toxicity were assessed. An interim overall survival (OS) analysis was performed. Results, when possible, were compared with the NETTER-1 trial. Lines of therapy were documented. Results: 22/52 (42%) patients completed all 4 cycles of PRRT. 18/52 (34%) patients are currently being treated. 12/52 (23%) patients had to discontinue treatment. Hematotoxicity was the only side effect which can be related to PRRT. The 6-month and 9-month PFS rate was 82.4% and 66.8% respectively vs. 89% and 84% in the NETTER-1 trial. The ORR was 36% vs. 18% in the NETTER-1 trial. In the interim OS analysis, 6 deaths occurred. In contrast to the NETTER-1 study, PRRT in our patient cohort was performed later in the course of treatment (median lines of therapy before PRRT = 4 ±1.3 (range 1-6)). Conclusions: Our preliminary data show overall good results of PRRT in patients with NETs. However, compared to the NETTER-1 trial, PFS is shorter which is most likely due to the extensive pretreatment, but ORR was higher. [Table: see text]

Abstract P6-01-04: Initial experience of dedicated breast PET imaging of ER+ breast cancers using [F-18]fluoroestradiol

Introduction: Breast cancer is a heterogeneous disease encompassing distinct subtypes with variable treatment response, relapse risk and overall prognosis. The majority of breast cancers are estrogen receptor-positive (ER+). While neoadjuvant endocrine therapy trials have been proposed to better identify therapeutic approaches for ER+ breast cancer, accurate quantification of the ER biomarker is necessary to assess the primary tumor and its likelihood of response to treatment.

Dedicated breast positron emission tomography (dbPET) is an emerging technology with a high spatial resolution that enables detection of sub-centimeter lesions and depiction of intratumoral heterogeneity. In this study, we report our initial experience with [F-18]fluoroestradiol (FES) dbPET in assessing ER+ primary breast cancers.

Materials and Methods: In an IRB-approved protocol, patients with biopsy-confirmed ER+ breast cancers were imaged with dbPET (MAMMI, OncoVision, Valencia, Spain) as a companion diagnostic tool to standard breast MRI. A dose of 5 mCi of FES was administered and patients were imaged in the prone position at 45 min post-injection. As part of routine clinical care, MR images were reviewed by a certified breast radiologist experienced in breast MRI. DbPET was reviewed by a radiologist specialized in nuclear imaging.

Results: Five patients with ER+ breast cancers were imaged. Patient ages ranged from 33 to 64. Two patients with infiltrating lobular carcinomas measuring up to 6.7 cm and 5.3 cm at MRI demonstrated corresponding FES tumor-to-normal maximum standard uptake value (SUVmax) ratio at 4.81 and 2.49 respectively. A third patient demonstrated multifocal FES uptake corresponding to multifocal invasive ductal carcinoma and ductal carcinoma in situ with disease foci ranging from 9-13 mm. In this patient, the more posterior disease foci seen on MRI were excluded from the field of view of dbPET. One patient demonstrated an absence of FES uptake in her 3.4 cm infiltrating ductal carcinoma, which was due to estrogen receptor blockade from the recent administration of tamoxifen for a fertility preservation procedure. The final patient had metastatic cervical and axillary lymphadenopathy secondary to a breast primary that was occult on mammography and MRI. FES-dbPET also showed no corresponding uptake in the ipsilateral breast, possibly due to the small size of the primary lesion and/or low tumor to background uptake ratio.

Conclusions: FES-dbPET imaging has potential as a diagnostic tool that is complementary to MRI in characterizing ER+ primary breast cancers. Limitations include variations of FES uptake in different ER+ breast cancer diseases and exclusion of posterior breast tissue near the chest wall and the axillary regions. However, FES-dbPET has a high potential for clinical utility, especially in measuring response to neoadjuvant endocrine treatment. Further development to improve the dbPET field of view and studies with a larger cohort of ER+ breast cancer patients are therefore warranted.

Citation Format: Jones EF, Ray KM, Mukhtar R, Li W, Franc BL, Esserman LJ, Joe BN, Pampaloni MH, Hylton NM. Initial experience of dedicated breast PET imaging of ER+ breast cancers using [F-18]fluoroestradiol [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-01-04.

Contextualizing the use of oncologic imaging within treatment phases: imaging trends and modality preferences, 2000-2014

BACKGROUND

In the present study, we retrospectively evaluated the use of tomographic imaging in adult cancer patients to clarify how recent growth plateaus in the use of tomographic imaging in the United States might have affected oncologic imaging during the same period.

METHODS

At a U.S. academic cancer centre, 12,059 patients with dates of death from January 2000 through December 2014 were identified. Imaging was restricted to brain and body computed tomography (ct), brain and body magnetic resonance (mr), and body positron-emission tomography (pet) with and without superimposed ct. Trends during the staging (1 year after diagnosis), monitoring (18-6 months before death), and end-of-life (final 6 months before death) phases were analyzed.

RESULTS

Comparing the 2005-2009 with the 2010-2014 period, mean intensity of pet imaging increased 21% during staging (p = 0.0000) and 27% during end of life (p = 0.0019). In the monitoring phase, mean intensity for ct brain, ct body, and mr body imaging decreased by 26% (p = 0.0133), 11% (p = 0.0118), and 26% (p = 0.0008), respectively. Aggregate mean intensity of imaging increased in the 13%-27% range every 3 months from 18 months before death to death, reaching 1.43 images in the final 3 months of life. Patients diagnosed in the final 18 months of life had an average of 1 additional image during both the 3 months after diagnosis (p = 0.0000) and the final 3 months before death (p = 0.0000).

CONCLUSIONS

Imaging increased as temporal proximity to death decreased, and patients diagnosed near death received more staging imaging, suggesting that imaging guidelines should consider imaging intensity within the context of treatment phase. Despite the development, by multiple organizations, of appropriateness criteria to reduce imaging utilization, aggregate per-patient imaging showed insignificant changes. Simultaneous fluctuations in the intensity of imaging by modality suggest recent changes in the modalities preferred by providers.