The hidden Australian skin cancer epidemic, high-risk cutaneous squamous cell carcinoma: a narrative review.

Deaths from non-melanoma skin cancers (NMSCs) have almost doubled in Australia in recent years. Cutaneous squamous cell carcinoma (cSCC) constitutes approximately 20% of NMSCs, but is responsible for most of the deaths. Most skin cancers are easy to diagnose and treat and therefore cSCC are often trivialised; however, there is a high-risk subgroup of cSCC (HRcSCC) that is associated with a high risk of metastasis and death. The definition of early HRcSCC and our ability to identify them is evolving. Many significant prognostic factors have been identified, but a universally accepted prognostic index does not exist. Guidelines for workup, treatment, and follow-up leave many important decisions open to broad interpretation by the treating physician or multidisciplinary team. Some of the treatments used for metastatic cSCC are not supported by robust evidence and the prognosis of metastatic cSCC is guarded. In this review, we highlight the rapid rise in NMSC deaths and discuss some of the deficiencies in our knowledge of how to define, diagnose, stage, and manage HRcSCC.

Sudden unilateral audiovestibular loss due to acute labyrinthine haemorrhage can be missed on early MRI brain sequences: case report.

Background: Labyrinthine haemorrhage is a rare vascular disorder often presenting with the triad of acute vertigo, sudden sensorineural hearing loss and tinnitus. There are minimal reports on imaging progression over the acute period. Index case: A woman in her mid-40s presented with acute vertigo, sudden left-sided hearing loss and tinnitus, consistent with acute unilateral audiovestibular loss. Left peripheral vestibular hypofunction was confirmed acutely on video head impulse testing, and pure tone audiometry showed a profound left sensorineural hearing loss. An MRI brain including diffusion-weighted imaging within 24 hours was normal. Delayed MRI brain and internal acoustic canal after 7 days demonstrated increased 3D fluid-attenuated inversion recovery and T1 signal throughout the left cochlea and semicircular canals, without contrast enhancement. This was consistent with labyrinthine haemorrhage. She received early oral prednisone followed by three doses of intratympanic dexamethasone. At 12 months follow-up the patient remained profoundly deaf, however, balance and vestibular symptoms improved with early vestibular physical rehabilitation. Conclusion: We report a case of acute labyrinthine haemorrhage missed on an early MRI brain sequence. This diagnosis should be considered in presentations of acute audiovestibular loss, and delayed MRI including internal auditory canal sequences may be important for diagnosis.

F18-FDG PET/CT accuracy in nodal staging of head and neck squamous cell carcinoma and correlation of SUVmax to the likelihood of a confirmed nodal metastasis.

INTRODUCTION: This study aimed to determine F18-Fluorodeoxyglucose Positron Emission Tomography/ Computerised Tomography (FDG-PET/CT) accuracy in nodal staging of head and neck squamous cell carcinoma (HNSCC) and investigate the relationship between increasing standard uptake value max (SUVmax) thresholds and the likelihood of a diagnosis of nodal malignancy on histopathological analysis. METHODS: Histopathological diagnosis was correlated retrospectively with the reported nodal involvement on PET/CT scans. Data was analysed to determine the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). SUVmax was measured for the most FDG-avid node in the nodal levels noted to be malignant on histopathological analysis and for those deemed malignant in the PET/CT report. A range of SUVmax thresholds was then applied retrospectively to calculate the corresponding likelihood of a node being truly malignant. RESULTS: The "per lymph node level" analysis (n=216) found accuracy of 81.5%, sensitivity of 68.8%, specificity of 85.1%, PPV of 59.9% and NPV of 90.5%. A strong positive correlation was found between the threshold SUVmax and the likelihood of a diagnosis of malignancy on histopathological analysis. A significant increase in likelihood from 72.2% to 83.3% was found when the SUVmax threshold was increased from 4.0 to 4.5. CONCLUSION: This study reinforces the utility of PET/CT as a diagnostic tool for ruling out malignant nodal dissemination due to its high NPV. Secondly, it shows a strong positive correlation between SUVmax of the lymph node and its likelihood of being malignant, which may assist in determining which lymph nodes should be biopsied.

Utility of positron emission tomography imaging in the diagnosis of chronic Q fever: A Systematic Review.

Chronic Q fever is a diagnostic challenge. Diagnosis relies on serology and/or the detection of DNA from blood or tissue samples. PET-CT identifies tissues with increased glucose metabolism, thus identifying foci of inflammation. Our aim was to review the existing literature on the use of PET-CT to help diagnose chronic Q fever. A literature search was conducted in PubMed and Google Scholar to ascertain publications that included the terms 'Positron Emission Tomography' and 'PET CT' in combination with subheadings 'chronic Q fever' and 'Coxiella burnetii' within the search. To broaden our search retrieval, we used the terms 'chronic Q fever' and 'PET-CT'. Published literature up to 16th April 2020 was included. 274 articles were initially identified. Post-exclusion criteria, 46 articles were included. Amongst case reports and series, the most frequent focus of infection was vascular, followed by musculoskeletal then cardiac. 79.5% of patients had a focus detected with 55.3% of these having proven infected prosthetic devices. Amongst the retrospective and prospective studies, a total of 394 positive sites of foci were identified with 186 negative cases. Some had follow-up scans (53), with 75.5% showing improvement or resolution. Average timeframe for documented radiological resolution post-initiating treatment was 8.86 months. PET-CT is a useful tool in the management of chronic Q fever. Knowledge of a precise focus enables for directed surgical management helping reduce microbial burden, preventing future complications. Radiological resolution of infection can give clinicians reassurance on whether antimicrobial therapy can be ceased earlier, potentially limiting side effects.

Prostate cancer GTV delineation with biparametric MRI and 68Ga-PSMA-PET: comparison of expert contours and semi-automated methods.

OBJECTIVE: The optimal method for delineation of dominant intraprostatic lesions (DIL) for targeted radiotherapy dose escalation is unclear. This study evaluated interobserver and intermodality variability of delineations on biparametric MRI (bpMRI), consisting of T2 weighted (T2W) and diffusion-weighted (DWI) sequences, and 68Ga-PSMA-PET/CT; and compared manually delineated GTV contours with semi-automated segmentations based on quantitative thresholding of intraprostatic apparent diffusion coefficient (ADC) and standardised uptake values (SUV). METHODS: 16 patients who had bpMRI and PSMA-PET scanning performed prior to any treatment were eligible for inclusion. Four observers (two radiation oncologists, two radiologists) manually delineated the DIL on: (1) bpMRI (GTVMRI), (2) PSMA-PET (GTVPSMA) and (3) co-registered bpMRI/PSMA-PET (GTVFused) in separate sittings. Interobserver, intermodality and semi-automated comparisons were evaluated against consensus Simultaneous Truth and Performance Level Estimation (STAPLE) volumes, created from the relevant manual delineations of all observers with equal weighting. Comparisons included the Dice Similarity Coefficient (DSC), mean distance to agreement (MDA) and other metrics. RESULTS: Interobserver agreement was significantly higher (p < 0.05) for GTVPSMA (DSC: 0.822, MDA: 1.12 mm) and GTVFused (DSC: 0.787, MDA: 1.34 mm) than for GTVMRI (DSC: 0.705, MDA 2.44 mm). Intermodality agreement between GTVMRI and GTVPSMA was low (DSC: 0.440, MDA: 4.64 mm). Agreement between semi-automated volumes and consensus GTV was low for MRI (DSC: 0.370, MDA: 8.16 mm) and significantly higher for PSMA-PET (0.571, MDA: 4.45 mm, p < 0.05). CONCLUSION: 68Ga-PSMA-PET appears to improve interobserver consistency of DIL localisation vs bpMRI and may be more viable for simple quantitative delineation approaches; however, more sophisticated approaches to semi-automatic delineation factoring for patient- and disease-related heterogeneity are likely required. ADVANCES IN KNOWLEDGE: This is the first study to evaluate the interobserver variability of prostate GTV delineations with co-registered bpMRI and 68Ga-PSMA-PET.

Focal 18F-DOPA Uptake in Brain Parenchyma Surrounding Developmental Venous Anomalies.

We report the finding of increased F-DOPA uptake within parenchyma surrounding a developmental venous anomaly, found incidentally in a 64-year-old woman undergoing PET scan to assess for Parkinson's disease. Not identified on previous T1/T2 MRI, susceptibility-weighted imaging MRI performed post-PET scan demonstrated the presence of developmental venous anomaly within the left cerebellar hemisphere. Focal uptake of F-DOPA may suggest the presence of a brain tumor and prompt invasive diagnostic investigations. Nuclear medicine physicians should be aware of this finding when interpreting F-DOPA PET and consider appropriate imaging to identify venous anomalies prior to more invasive investigations for possible brain tumors.

Pilot study: use of gallium-68 PSMA PET for detection of metastatic lesions in patients with renal tumour.

BACKGROUND: In this study, we prospectively evaluate the diagnostic potential of a gallium-68 (68Ga) prostate-specific membrane antigen (PSMA)-binding ligand and positron emission tomography (PET) in detecting metastatic lesions in patients with renal tumour. The secondary aim was to determine whether the findings would result in the alteration of patient management. RESULTS: Ten patients with renal lesion and potential metastatic disease on conventional imaging were recruited. Patients underwent PSMA PET in addition to standard imaging. Nine patients underwent nephrectomy and 4 patients underwent additional targeted biopsy to provide specimens for histopathological validation. There were 89 pathological lesions on CT, of which 32 were removed or biopsied for histopathological correlation. With PSMA PET, 86 PET avid lesions were identified with 36 samples being available for analysis. Thirty-five of 36 samples were positive for renal cell carcinoma deposits, whilst 1 sample was inconclusive for diagnosis on biopsy. For the histologically confirmed lesions, there were no false-negative PSMA PET lesions; however, CT was false negative in 11. In two patients, surgical strategies were changed based on PSMA PET findings. CONCLUSIONS: PSMA PET may potentially have a role in the preoperative staging of advanced renal cell carcinoma as PET detected multiple histologically proven metastatic lesions which were false negative on CT scanning, resulting in change in surgical strategies in some patients. We cautiously support a larger study to confirm these results and to assess the longitudinal impact on patient outcomes. TRIAL REGISTRATION: Australia and New Zealand Clinical Trial Registry (ANZCTR), ACTRN12615000854538 .

Paget Disease: A Potential Pitfall in PSMA PET for Prostate Cancer.

We present a case of an 81-year-old man with multifocal Paget disease found on bone scan that was performed for incidentally diagnosed prostate cancer. The subsequent Ga-PSMA (HBED-CC) PET scan also displayed increased uptake in the same distribution. Multiple known tumors display increased Ga-PSMA uptake due to neovasculature. We postulate that increased Ga-PSMA uptake within the pagetoid bone relates to neovascularity known to occur in Paget disease. Such pagetic uptake could result in false-positive studies for bone metastases, particularly in the setting of less typical Paget disease.

Palpation thyroiditis seen on F-18 FDG PET/CT.

A 29-year-old woman presented with a new right supraclavicular mass on a background of resection of a malignant melanoma from her right shoulder before 4 years. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging revealed uptake in a right supraclavicular node and the inferior pole of the left lobe of the thyroid gland. Subsequent resection and histology of the right supraclavicular node and the left lobe of the thyroid gland demonstrated metastatic melanoma and palpation thyroiditis, respectively. A number of malignant and benign pathologies of the thyroid demonstrate FDG uptake, with 75% being benign. To our knowledge, the findings of palpation thyroiditis on FDG PET/CT have never been previously described.