Quarter Century PET/Computed Tomography Transformation of Oncology: Neuroendocrine Tumors.

Significant improvement in molecular imaging and theranostics in the management of neuroendocrine tumors (NETs) has been made in the last few decades. Somatostatin receptor-targeted PET imaging outperforms conventional, planar, and single-photon emission computed tomography imaging and is indicated in the evaluation of these patients when available, resulting in a significant impact on staging, treatment response assessment, and restaging of these patients. Radionuclide therapy can have an impact on patient outcome in metastatic disease when not many treatment options are available.

Evaluation of Treatment Response in Patients with Breast Cancer.

Breast cancer (BC) remains one of the leading causes of death among women. The management and outcome in BC are strongly influenced by a multidisciplinary approach, which includes available treatment options and different imaging modalities for accurate response assessment. Among breast imaging modalities, MR imaging is the modality of choice in evaluating response to neoadjuvant therapy, whereas F-18 Fluorodeoxyglucose positron emission tomography, conventional computed tomography (CT), and bone scan play a vital role in assessing response to therapy in metastatic BC. There is an unmet need for a standardized patient-centric approach to use different imaging methods for response assessment.

A Discordant Pattern of Uptake on 68 Ga-PSMA PET/CT Versus 18 F-Fluciclovine PET/CT in Radiation-Induced Hepatitis : Implications for Early Postradiotherapy Imaging-Based Response Assessment.

ABSTRACT: A 62-year-old woman with right-sided invasive lobular breast carcinoma completed external beam radiotherapy 6 weeks before undergoing a 68 Ga-PSMA PET/CT and 18 F-fluciclovine PET/CT scan as part of an ongoing clinical trial (NCT04750473) assessing the performance of these molecular imaging modalities in invasive lobular breast carcinoma. The 68 Ga-PSMA PET/CT demonstrated a band-like area of increased radiotracer uptake in the dome of the right lobe of the liver anteriorly, whereas 18 F-fluciclovine PET/CT done a day later revealed photopenia in the corresponding area of the liver. The external beam radiotherapy plan confirmed that the radiotherapy field overlaid the region of the hepatic discordant radiotracer uptake on the PET/CT scans.

A Tale of 3 Tracers: Contrasting Uptake Patterns of 18F-Fluciclovine, 68Ga-PSMA, and 18F-FDG in the Uterus and Adnexa.

ABSTRACT: A 41-year-old woman with invasive lobular carcinoma of the breast underwent sequential 68Ga-PSMA-11 PET/CT and 18F-fluciclovine PET/CT as part of an ongoing clinical trial (NCT04750473). 68Ga-PSMA PET/CT showed increased radiotracer uptake in the uterine endometrium and left adnexa. 18F-fluciclovine PET/CT showed increased radiotracer uptake in a leiomyomatous uterus. A clinical 18F-FDG PET/CT demonstrated radiotracer uptake in the endometrium and a circumferential area of uptake in the left adnexa, a pattern more similar to the 68Ga-PSMA uptake pattern. This case highlights the discordance in the uptake pattern of 2 radiotracers approved for prostate cancer imaging but increasingly used in non-prostate malignancies imaging.

The Role of SPECT/CT in Peritoneal Scintigraphy in the Era of Low-Dose Imaging: A Case Report.

Peritoneal scintigraphy, although rarely used, plays a vital role in the diagnosis of peritoneal dialysis catheter complications. Reported complications include spontaneous hydrothorax secondary to a pleuroperitoneal fistula, which requires the abandonment of peritoneal dialysis, given that a delay in diagnosis can lead to worsening clinical status. Previously reported peritoneal scintigraphy protocols recommended intraperitoneal instillation of radiotracer and moderate-to-large volumes of dialysate or sterile saline ranging from 350 to 2,000 mL. However, smaller volumes, in conjunction with the use of single-photon emission computed tomography/computed tomography, are not verified in patients receiving peritoneal scintigraphy imaging.

Rare presentation of inflammatory pseudotumour involving subcutaneous tissues with superficial fat sparing.

We present a unique case of inflammatory pseudotumour involving gluteal subcutaneous tissue with the sparing of superficial fat and report its contrast-enhanced CT, F-18 fluorodeoxyglucose positron emission tomography/CT and pathological findings. Although rare, inflammatory pseudotumours have been reported with a diverse spectrum of locations; however, the involvement of the subcutaneous tissue overlying the gluteal muscles with sparing of the most superficial fat has not been reported.

Molecular Breast Cancer Imaging in the Era of Precision Medicine.

OBJECTIVE. Precision medicine in oncology aims to individualize the patient's treatment and management regimen according to the accurate assessment of diagnosis, risk of recurrence, or progression. In this review, we will discuss the evolving role of molecular imaging (breast-specific gamma imaging and positron emission mammography) toward precision medicine in patients with breast cancer. CONCLUSION. Incorporating molecular imaging for breast cancer will lead to precision medicine, which holds promise to facilitate appropriate personalized treatment in patients with breast cancer.

(18)F-FDG PET/CT and pain in metastatic bone cancer.

This study aims to determine if the pain intensity of patients with oncologic bone metastases (BM) correlates with metabolic activity measured by (18)F-FDG PET/CT. Twenty-eight patients, ages: 21-89 years (mean: 58.8) with BM were included in the study between September 2011 to September 2013. All patients completed a detailed questionnaire regarding pain symptoms on the visual analog scale (VAS), analgesic use, and areas of chronic pain, prior to obtaining an (18)F-FDG PET/CT. Pain symptoms were queried for 11 body regions including limbs, head, torso, etc. and the corresponding SUVmax of BMs within that region were modeled with the corresponding clinical data using a linear mixed effects model and a linear regression model. Overall 64 areas in the 28 subjects were found to have BM. SUVmax was found to be a significant predictor of pain intensity as measured by the VAS, with a P-value of 0.045, with a modest effect-size on linear regression of R(2) of 0.11.

Differentiation of metastatic vs degenerative joint disease using semi-quantitative analysis with (18)F-NaF PET/CT in castrate resistant prostate cancer patients.

Fluorine 18 Sodium Fluoride ((18)F-NaF) (sodium fluoride) PET/CT is a highly sensitive but is a non-specific method for identifying bone metastases. Qualitative scan interpretation using low dose CT for lesion localization is often complicated by the presence of co-existing degenerative joint disease (DJD). A semi-quantitative analysis might help in accurately differentiating benign from metastatic osseous lesions. The aim of the study was to evaluate the clinical utility of (18)F-NaF PET/CT in differentiating DJD from metastatic disease in the skeleton using a qualitative analysis as well as a semi-quantitative approach using the SUVmax and to determine if there is an upper limit of SUVmax value that can reliably differentiate metastases from DJD. Baseline (18)F-NaF PET/CT scans were performed for 17 castrate resistant prostate cancer patients (CRPC). A qualitative as well as semi-quantitative analysis using maximum standardized uptake value (SUVmax) based on body weight was performed for 65 metastatic and 56 DJD sites identified on the low dose CT scan acquired as a part of whole body PET/CT scan. The SUVmax range in DJD was 2.6-49.9 (mean: 6.2). The SUVmax range for metastatic lesions was 11.2-188 (mean: 160). The SUVmax value for metastatic as well as areas of DJD showed significant variation during treatment. Bone metastases showed statistically significantly higher SUVmax than DJD using a mixed effect regression model. ROC/AUC analysis was performed based on averaging the SUVs over all lesions in each subject. The AUC was found to be fairly high at 0.964 (95% CI: 0.75-0.996). The SUVmax over 50 always represented a bone metastasis and below 12 always represented a site of DJD. The results of our preliminary data show that semi-quantitative analysis is complementary to the qualitative analysis in accurately identifying DJD from metastatic disease. The cut-off SUVmax of 50 can help in differentiating DJD from bone metastases.

Feasibility and advantage of adding (131)I-MIBG to (90)Y-DOTATOC for treatment of patients with advanced stage neuroendocrine tumors.

BACKGROUND: Peptide receptor radionuclide therapy (PRRT) is an effective form of treatment for patients with metastatic neuroendocrine tumors (NETs). However, delivering sufficient radiation dose to the tumor to result in a high percentage of long-term tumor remissions remains challenging because of the limits imposed on administered activity levels by radiation damage to normal tissues. The goal of this study was to evaluate the dosimetric advantages of adding (131)I meta-iodobenzylguanidine ((131)I-MIBG) to (90)Y DOTA Phe1-Tyr3-octreotide ((90)Y-DOTATOC) in patients with advanced stage midgut NETs. METHODS: Ten patients were imaged simultaneously with (131)I-MIBG and (111)In-pentetreotide (as a surrogate for (90)Y-DOTATOC) on days 1, 2, and 3 post-administration. Blood samples were obtained at the same time points. Using dosimetry measures from this data and our previously published methodology for calculating optimal combined administered activity levels for therapy, we determined the amount of (131)I-MIBG that could be added to (90)Y-DOTATOC without exceeding normal organ dose limits (marrow and kidneys) along with the expected increase in associated tumor dose, if any. RESULTS: We found that a median value of 34.6 GBq of (131)I-MIBG could be safely added to (90)Y-DOTATOC (delivered over multiple cycles) by reducing the maximum total deliverable (90)Y-DOTATOC by a median value of 24.5%. Taking this treatment approach, we found that there would be a median increase in deliverable tumor dose of 4,046 cGy in six of the ten subjects. Of note, there were a small number of metastases that were positive for only one or the other of these radiopharmaceuticals within the same subject. CONCLUSIONS: We conclude that approximately half of the patients with midgut NETs that are eligible for PRRT could reasonably be expected to benefit from the addition of (131)I-MIBG to (90)Y-DOTATOC.

Management of contralateral axillary sentinel lymph nodes detected on lymphoscintigraphy for breast cancer.

BACKGROUND: Detection of a contralateral axillary sentinel lymph node (SLN) during lymphoscintigraphy for breast cancer is rare, and its significance and management are unclear. The purpose of this study was to review our experience and analyze our results together with similar patients in the literature to identify common characteristics and propose a management strategy. METHODS: A PubMed search was performed for articles describing patients in whom contralateral axillary drainage was identified on lymphoscintigraphy. Additionally, a chart review was performed of all patients who had lymphoscintigraphy for breast cancer at our institution. RESULTS: At our institution, two of 988 (0.3 %) consecutive patients were identified with contralateral axillary drainage on lymphoscintigraphy. Twenty-seven publications describing 105 patients with contralateral axillary drainage were found. This comprised our study group of 107 patients. Lymphoscintigraphy patterns varied depending on the history and type of prior surgery. A history of chest/axillary surgery was significantly associated with absence of an ipsilateral SLN (p < 0.05). This was observed in 84.2 % of patients with prior axillary lymph node dissection versus 33.3 % with prior SLN. Contralateral SLN biopsy was attempted in 85 patients (79.4 %); 22 (20.6 %) were positive for tumor. In 17 patients (15.9 %), the contralateral node was the only positive SLN. CONCLUSIONS: These findings suggest that contralateral uptake on lymphoscintigraphy, though rare (0.2 %), is clinically significant and such nodes should undergo excision. Because contralateral uptake is significantly associated with prior chest/axillary surgery, routine lymphoscintigraphy should be considered in this group, as it has potential to change disease stage and management.