False positive FDG uptake in melanoma patients treated with talimogene laherparepvec (T-VEC).

Talimogene laherparepvec (T-VEC) is a genetically modified herpes simplex virus-1-based oncolytic immunotherapy and has been approved for the local treatment of unresectable (stage IIIB/C and IVM1a) cutaneous melanoma. During T-VEC treatment, tumor response is often evaluated using [18F]2-fluoro-2-deoxy- d-glucose(FDG) positron emission tomography/computed tomography (PET/CT). In a Dutch cohort (n = 173), almost one-third of patients developed new-onset FDG uptake in uninjected locoregional lymph nodes during T-VEC. In 36 out of 53 (68%) patients with new nodal FDG uptake, nuclear medicine physicians classified this FDG uptake as "suspected metastases" without clinical or pathological confirmation in the majority of patients. These false positive results indicate that new-onset FDG uptake in locoregional lymph nodes during T-VEC treatment does not necessarily reflect progressive disease, but may be associated with immune infiltration. In current clinical practice, physicians should be aware of the high false positive rate of FDG uptake during treatment with T-VEC in patients with melanoma. Therefore, pathological examination of lymph node lesions with new FDG uptake is recommended to differentiate between progressive disease and immune infiltration after treatment with T-VEC.

Localization of parathyroid adenomas using 11C-methionine pet after prior inconclusive imaging.

PURPOSE: Minimally invasive parathyroidectomy (MIP) is the recommended treatment in primary hyperparathyroidism (pHPT) for which accurate preoperative localization is essential. The current imaging standard consists of cervical ultrasonography (cUS) and MIBI-SPECT/CT. 11C-MET PET/CT has a higher resolution than MIBI-SPECT/CT. The aim of this study was to determine the diagnostic performance of 11C-MET PET/CT after initial inconclusive or negative localization. METHODS: We performed a retrospective single center cohort study of patients with pHPT undergoing parathyroid surgery after prior negative imaging and later localization by means of 11C-MET PET/CT between 2006 and 2014. Preoperative localization by 11C-MET PET/CT was compared with later surgical localization, intraoperative quick PTH (IOPTH), duration of surgery, histopathology, and follow-up data. Also, differences in duration of surgery between the groups with and without correct preoperative localization were analyzed. RESULTS: In 18/28 included patients a positive 11C-MET-PET/CT result corresponded to the surgical localized adenoma (64%). In 3/28 patients imaging was false positive and no adenoma was found. In 7/28 patients imaging was false negative at the side of the surgically identified adenoma. Sensitivity of 11C-MET PET/CT was 72% (18/25). Duration of surgery of correctly localized patients was significantly shorter compared to falsely negative localized patients (p = 0.045). CONCLUSION: In an intention to treat 11C-MET-PET/CT correctly localized the parathyroid adenoma in 18/28 (64%) patients, after previous negative imaging. A preoperatively correct localized adenoma leads to a more focused surgical approach (MIP) potentially reducing duration of surgery and potentially healthcare costs.

Limited value of staging squamous cell carcinoma of the anal margin and canal using the sentinel lymph node procedure: a prospective study with long-term follow-up.

BACKGROUND: Selection of patients with anal cancer for groin irradiation is based on tumor size, palpation, ultrasound, and fine needle cytology. Current staging of anal cancer may result in undertreatment in small tumors and overtreatment of large tumors. This study reports the feasibility of the sentinel lymph node biopsy (SLNB) in patients with anal cancer and whether this improves the selection for inguinal radiotherapy. METHODS: A total of 50 patients with squamous anal cancer were evaluated prospectively. Patients without a SLNB (n = 29) received irradiation of the inguinal lymph nodes based on lymph node status, tumor size, and location of the primary tumor. Inguinal irradiation treatment in patients with a SLNB was based on the presence of metastases in the SLN. RESULTS: SLNs were found in all 21 patients who underwent a SLNB. There were 5 patients (24%) who had complications after SLNB and 7 patients (33%) who had a positive SLN and received inguinal irradiation. However, 2 patients with a tumor-free SLN and no inguinal irradiation developed lymph node metastases after 12 and 24 months, respectively. CONCLUSIONS: We conclude that SLNB in anal cancer is technically feasible. SLNB can identify those patients who would benefit from refrain of inguinal irradiation treatment and thereby reducing the incidence of unnecessary inguinal radiotherapy. However, because of the occurrence of inguinal lymph node metastases after a tumor-negative SLNB, introduction of this procedure as standard of care in all patients with anal carcinoma should be done with caution to avoid undertreatment of patient who otherwise would benefit from inguinal radiotherapy.

Utility of an intraoperative gamma probe in the surgical management of secondary or tertiary hyperparathyroidism.

BACKGROUND: In primary hyperparathyroidism the gamma probe is effective, but its role in secondary hyperparathyroidism is unclear. We investigated the utility of the probe in the surgical management of secondary and tertiary hyperparathyroidism. METHODS: The value of the probe in guiding resection of parathyroids was determined prospectively in 29 patients with secondary or tertiary hyperparathyroidism. Resected tissues with radioactivity of greater than 20% as compared with the wound bed was considered hyperfunctional parathyroid and was confirmed histologically. RESULTS: The probe was helpful in guiding resection in 13% of the hyperplastic glands, including ectopic glands and those not detected preoperatively. The gamma probe confirmed the presence of hyperfunctional parathyroid after resection with a sensitivity and specificity of 97% and 92%, respectively. CONCLUSIONS: The probe is particularly useful in confirming the presence of hyperfunctional parathyroids after resection. It also is useful in identifying ectopic localizations, but its value is limited in guiding surgery for secondary or tertiary disease.

Value of 123I-subtraction and single-photon emission computed tomography in addition to planar 99mTc-MIBI scintigraphy before parathyroid surgery.

PURPOSE: To find out if single-photon emission computed tomography (SPECT) and (123)I-subtraction can enhance the findings of (99m)Tc-methoxyisobutylisonitrile (MIBI) scintigraphy for the preoperative localization of parathyroid (PT) tumors. METHODS: Among the 111 consecutive patients who underwent preoperative planar (99m)Tc-MIBI scintigraphy for hyperparathyroidism (HPT), 64 underwent delayed SPECT, and 17 underwent (123)I-subtraction. Two independent blinded experts scored the topographical localization, diagnostic confidence, and impact of each diagnostic modality on the surgical strategy. RESULTS: For adenomas, (99m)Tc-MIBI scintigraphy had a sensitivity of 77% with a positive predictive value (PPV) of 83%. SPECT did not affect the sensitivity or PPV, but it increased the diagnostic confidence and changed the surgical strategy in 21% of the patients. (123)I-subtraction increased the sensitivity from 64% to 82%, but decreased the PPV from 88% to 82%. In hyperplastic glands, (99m)Tc-MIBI scintigraphy had a sensitivity of 47% and a PPV of 95%. When (99m)Tc-MIBI scintigraphy was combined with SPECT and (123)I-subtraction, the results were 44%/10% and 52%/92%, respectively. Both SPECT and (123)I-subtraction decreased the diagnostic confidence. CONCLUSIONS: Adding SPECT to (99m)Tc-MIBI scintigraphy improved the surgical decision for parathyroid adenomas. The addition of (123)I-subtraction was of limited value. For hyperplastic glands, (99m)Tc-MIBI scintigraphy was relatively ineffective, even with the addition of SPECT or (123)I-subtraction.

Immediate dynamic lymphoscintigraphy delivers no additional value to lymphoscintigraphy 3 hr after tracer injection in sentinel lymph node biopsy in breast cancer patients.

OBJECTIVE: Immediate dynamic imaging enables accurate definition of sentinel lymph nodes, whereas imaging 3 hr after tracer injection may lead to overestimation of the number of sentinel lymph nodes. A study was performed to define the value of lymphoscintigraphy immediately versus 3 hr after tracer injection in sentinel lymph node biopsy for breast cancer management. METHODS: In 165 sentinel lymph node biopsy procedures preoperative immediate and 3 hr post-injection lymphoscintigraphy was performed after intraparenchymal tracer administration. RESULTS: Lymph node visualization occurred in 63 immediate procedures (38%) versus in 163 procedures 3 hr post-injection (99%). In 17 procedures (10%) in which immediate lymphoscintigraphy had visualized sentinel lymph nodes, additional nodes had been seen on 3 hr post-injection lymphoscintigraphy. In eight of these procedures (5%) all nodes were detected in the same draining lymph node basin. Non-axillary sentinel lymph nodes were identified by preoperative lymphoscintigraphy in 28 procedures (17%) and improved staging in three patients (5%). CONCLUSION: The only impact of immediate lymphoscintigraphy was the possible omission of removal of 1-2 sec-echelon nodes per patient in 5% of patients. We consider this yield too low to continue immediate lymphoscintigraphy in breast cancer patients.