Introduction: Early localisation of disease recurrence after definitive treatment of prostate cancer is vital to determine suitability for salvage treatment. Our aim was to further investigate the relationship between prostate specific antigen (PSA) level and detection of suspected cancer recurrence using ⁶⁸  Ga‐ PSMA PET / CT in patients with biochemical recurrence after radical prostatectomy ( RP ) or radiotherapy, particularly at low PSA levels. Methods: This retrospective single tertiary referral institution cohort study of men reviewed the results of ⁶⁸  Ga‐ PSMA PET / CT scans for investigation of post RP and post radiotherapy PSA recurrence following primary treatment of prostate cancer. We included men with suspected recurrent prostate cancer based on an elevated post treatment PSA level. The data collected analyzed the relationship of the pre‐scan PSA level to the probability of a positive scan finding for recurrent prostate cancer. Results: Of the cohort of 532 men, 425 had a previous RP and 107 had prior radiotherapy. The median PSA of the RP group was 0.59 ng/mL and 5.8 ng/mL in the radiotherapy group. In the post RP cohort, the detection rate of ⁶⁸  Ga‐ PSMA PET / CT was 11.3% for PSA 0.01 to <0.2 ng/mL, 26.6% for PSA 0.2 to <0.5 ng/mL, 53.3% for PSA 0.5 to <1 ng/mL, 79.1% for PSA 1 to <2 ng/mL and 95.5% for PSA ≥2. Lymph node metastasis post RP was identified in 68% of men with suspected disease recurrence. In the post radiotherapy cohort the detection rate was 33.3% for PSA 0.01 to <0.5 ng/mL, 71.4% for PSA 0.5 to <1 ng/mL, 93.3% for PSA 1 to <2 ng/mL and 100% for PSA ≥2. Local recurrence after radiotherapy was suspected in 71% of the cohort and 40% had suspected lymph node metastasis. Conclusions: To our knowledge, this is largest cohort study of detection rates of ⁶⁸  Ga‐ PSMA PET / CT in patients with biochemical recurrence after definitive treatment of prostate cancer, including patients with PSA <0.5 and in a post radiotherapy cohort. Detection of suspected recurrent disease outside the pelvis at low PSA levels will influence the decision for salvage treatment options.

Objective To assess the efficacy of bilateral pedunculopontine nucleus (PPN) deep brain stimulation (DBS) as a treatment for primary progressive freezing of gait (PPFG). Methods A patient with PPFG underwent bilateral PPN-DBS and was followed clinically for over 14 months. Results The PPFG patient exhibited a robust improvement in gait and posture following PPN-DBS. When PPN stimulation was deactivated, postural stability and gait skills declined to pre-DBS levels, and fluoro-2-deoxy-d-glucose positron emission tomography revealed hypoactive cerebellar and brainstem regions, which significantly normalised when PPN stimulation was reactivated. Conclusions This case demonstrates that the advantages of PPN-DBS may not be limited to addressing freezing of gait (FOG) in idiopathic Parkinson's disease. The PPN may also be an effective DBS target to address other forms of central gait failure.

Objectives: To evaluate the safety and short‐term oncological outcomes of ⁶⁸ gallium‐labelled prostate‐specific membrane antigen ( ⁶⁸ Ga‐ PSMA ) positron‐emission tomography ( PET )/computed tomography ( CT )‐directed robot‐assisted salvage node dissection ( RASND ) for prostate cancer oligometastatic nodal recurrence. Materials and Methods: Between February 2014 and April 2016, 35 patients across two centres underwent RASND for ⁶⁸ Ga‐ PSMA PET / CT ‐detected oligometastatic nodal recurrence. RASND was performed using targeted pelvic dissection, unilateral extended pelvic template or bilateral extended pelvic template dissection, depending on previous pelvic treatment and extent/location of nodal disease. Complications were reported using the Clavien–Dindo classification system. Definitions of prostate‐specific antigen ( PSA ) treatment response to RASND were defined as 6‐week PSA <0.2 ng/ mL (broad definition) or PSA <0.05 ng/ mL (strict definition) in those who had undergone primary prostatectomy, and 6‐week PSA level < post‐radiotherapy nadir in those who had undergone primary radiotherapy. Biochemical recurrence ( BCR ) after RASND was defined as a PSA >0.2 ng/ mL or PSA > nadir, for those who had undergone primary prostatectomy and primary radiotherapy, respectively. Predictors of treatment response were analysed using univariate binary logistic regression. Results: A total of 58 lesions suspicious for lymph node metastases ( LNM ) in 35 patients were detected on ⁶⁸ Ga‐ PSMA imaging. A total of 32 patients (91%) had histopathologically proven LNM at RASND , with a total of 87 LNM and a median (interquartile range) of 2 (1–3) LNM per patient. In all, eight patients (23%) experienced complications, all Clavien–Dindo grade ≤2. Treatment response was seen in 15 (43%) and 11 patients (31%), using the broad and strict definitions, respectively. BCR ‐free survival and clinical recurrence‐free survival at a median follow‐up of 12 months were 23% and 66%, respectively, for the entire cohort. Bilateral template dissection was the only significant univariate predictor of treatment response in our cohort. Conclusions: Although RASND appears safe and feasible, less than half of our cohort had a treatment response, and less than a quarter experienced BCR ‐free survival at 12‐month median follow‐up. ⁶⁸ Ga‐ PSMA imaging underestimates micro‐metastatic disease, therefore RASND will rarely be curative. Strict patient selection and restricting RASND to clinical trials is recommended. Long‐term follow‐up from such trials is required to further assess potential quality of life and mortality benefits.