Metabolic characterization of structural lung changes in patients with findings suggestive of incidental COVID-19 pneumonia on 18F-FDG PET/CT. Pathophysiological insights from multimodal images obtained during the pandemic.

PURPOSE: To evaluate the metabolic uptake of different tomographic signs observed in patients with incidental structural findings suggestive of COVID-19 pneumonia through 18F-FDG PET/CT. MATERIALS AND METHODS: We retrospectively analyzed 596 PET/CT studies performed from February 21, 2020 to April 17, 2020. After excluding 37 scans (non-18F-FDG PET tracers and brain studies), we analyzed the metabolic activity of several structural changes integrated in the CO-RADS score using the SUVmax of multimodal studies with 18F-FDG. RESULTS: Forty-three patients with 18F-FDG PET/CT findings suggestive of COVID-19 pneumonia were included (mean age: 68±12.3 years, 22 male). SUVmax values were higher in patients with CO-RADS categories 5-6 than in those with lower CO-RADS categories (6.1±3.0 vs. 3.6±2.1, p=0.004). In patients with CO-RADS 5-6, ground-glass opacities, bilaterality and consolidations exhibited higher SUVmax values (p-values of 0.01, 0.02 and 0.01, respectively). Patchy distribution and crazy paving pattern were also associated with higher SUVmax (p-values of 0.002 and 0.01). After multivariate analysis, SUVmax was significantly associated with a positive structural diagnosis of COVID-19 pneumonia (odds ratio=0.63, 95% confidence interval=0.41-0.90; p=0.02). The ROC curve of the regression model intended to confirm or rule out the structural diagnosis of COVID-19 pneumonia showed an AUC of 0.77 (standard error=0.072, p=0.003). CONCLUSIONS: In those patients referred for standard oncologic and non-oncologic indications (43/559; 7.7%) during pandemic, imaging with 18F-FDG PET/CT is a useful tool during incidental detection of COVID-19 pneumonia. Several CT findings characteristic of COVID-19 pneumonia, specifically those included in diagnostic CO-RADS scores (5-6), were associated with higher SUVmax values.

Contralateral axillary sentinel lymph node drainage in breast cancer: Controversies and management according to the literature. A case report. / Drenaje del ganglio centinela a axila contralateral en cáncer de mama: controversias y manejo según la literatura. A propósito de un caso.

Lymphoscintigraphy in breast cancer usually shows lymphatic drainage to the ipsilateral axilla. Drainage to extraaxillary or contralateral axillary regions is rare and there is still controversy about its management. Due to the significant clinical impact of an accurate staging, a literature research is made based on a case of a patient with recurrence of left breast cancer with contralateral axillary sentinel lymph node detection, without evidence of lymphatic drainage to other locations.

18F-choline PET/MRI in suspected recurrence of prostate carcinoma. / PET/RM con 18F-colina en la sospecha de recurrencia del carcinoma de próstata.

OBJECTIVE: To evaluate the usefulness of simultaneous 18F-choline PET/MRI in the suspicion of prostate cancer recurrence and to relate 18F-choline PET/MRI detection rate with analytical and pathological variables. MATERIAL AND METHODS: 27 patients with prostate cancer who received local therapy as primary treatment underwent a 18F-choline PET/MRI due to suspicion of recurrence (persistently rising serum PSA level). 18F-choline PET/MRI findings were validated by anatomopathological analysis, other imaging tests or by biochemical response to oncological treatment. RESULTS: 18F-choline PET/MRI detected disease in 15 of 27 patients (detection rate 55.56%). 4 (15%) presented exclusively local recurrence, 5 (18%) lymph node metastases and 7 (26%) bone metastases. Mean PSA (PSAmed) at study time was 2.94ng/mL (range 0.18-10ng/mL). PSAmed in patients with positive PET/MRI was 3.70ng/mL (range 0.24-10ng/mL), higher than in patients with negative PET/MRI, PSAmed 1.97ng/mL (range 0.18-4.38ng/mL), although without statistically significant differences. Gleason score at diagnosis in patients with a positive study was 7.33 (range 6-9) and in patients with a negative study was 7 (range 6-9), without statistically significant differences. CONCLUSION: 18F-choline PET/MRI detection rate was considerable despite the relatively low PSA values in our sample. The influence of Gleason score and PSA level on 18F-choline PET/MRI detection rate was not statistically significant.

PET-CT in presurgical lymph node staging in non-small cell lung cancer: the importance of false-negative and false-positive findings. / La PET-TC en la estadificación ganglionar prequirúrgica del carcinoma de pulmón de células no pequeñas: implicación de los falsos negativos y falsos positivos.

OBJECTIVE: To assess the importance of false-negative and false-positive findings in computed tomography (CT) and 18F-FDG positron emission tomography (PET) in mediastinal lymph node staging in patients undergoing surgery for non-small cell lung cancer (NSCLC). MATERIAL AND METHODS: This retrospective study included 113 consecutive patients and 120 resected NSCLCs; 22 patients received neoadjuvant treatment. We compared the findings on preoperative 18F-FDG PET-CT studies with the postoperative pathology findings. Lymph node size and primary tumor size were measured with CT, and lymph nodes and primary tumors were evaluated qualitatively and semiquantitatively (using standardized uptake values (SUVmax)) with PET. RESULTS: Metastatic lymph nodes were found in 26 (21.7%) of the 120 tumors and in 41 (7.7%) of the 528 lymph node stations analyzed. 18F-FDG PET-CT yielded 53.8% sensitivity, 76.6% specificity, 38.9% positive predictive value, 85.7% negative predictive value, and 71.7% diagnostic accuracy. The false-negative rate was 14.2%. Multivariable analysis found that the factors associated with false-negative findings were a moderate degree of differentiation in the primary tumor (p = 0.005) and an SUVmax of the primary tumor >4 (p = 0.027). The false-positive rate was 61.1%, and the multivariable analysis found that lymph node size >1cm was associated with false-positive findings (p < 0.001). CONCLUSIONS: In mediastinal lymph node staging in patients with NSCLC, 18F-FDG PET-CT improves the specificity and negative predictive value and helps clinicians to select the patients that will benefit from surgery. Given the high rate of false positives, histological confirmation of positive cases is recommendable.

Simultaneous PET/MRI vs PET/CT in oncology. A systematic review. / PET/RM simultánea vs. PET/TC en oncología. Una revisión sistemática.

OBJECTIVE: The aim of this review was to evaluate the diagnostic performance of simultaneous PET/MRI in oncology compared with that of PET/CT, based upon the available evidence. MATERIAL AND METHODS: A systematic search was performed in the Medline and Embase databases to identify original clinical articles published up to 21 January 2016, in order to compare simultaneous PET/MRI and PET/CT in oncology patients. RESULTS: A total of 57 articles were obtained that included various diseases: head and neck cancer (5), lung cancer and lung nodules (13), colorectal cancer (1), liver lesions (2), abdominal incidentalomas (1), neuroendocrine tumours (2), thyroid carcinoma (2), breast cancer (3), gynaecological cancer (2), prostate cancer (4), lymphoma (2), multiple myeloma (1), bone metastases (3), intracranial tumours (2), paediatric oncology (1) and various tumours (13). Diagnostic performance of simultaneous PET/MRI was similar or even better to that of PET/CT in most oncological diseases. However, PET/CT was superior for small lung nodule detection. CONCLUSION: Simultaneous PET/MRI in oncology is feasible, performing at least equally as well as PET/CT, with lower radiation exposure. However, available evidence is still limited. Studies including more patients and tumours are needed to establish PET/MRI indications and to identify appropriate protocols for each disease.

18F-FDG PET/CT and functional MRI in a case of crossed logopenic primary progressive aphasia. / 18F-FDG PET/TC y RM funcional en un caso de afasia progresiva primaria logopénica cruzada.

Primary progressive aphasia is a clinical syndrome caused by a neurodegeneration of areas and neural networks involved in language, usually in the left hemisphere. The term "crossed aphasia" denotes an acquired language dysfunction caused by a lesion in the hemisphere ipsilateral to the dominant hand. A case is presented on a 75-year-old right-handed woman with a logopenic variant of primary progressive aphasia with word-finding difficulties of 2 years onset. The 18F-FDG PET/CT showed right temporoparietal hypometabolism. A functional MRI scan was performed during a verb naming task in order to characterise language lateralisation patterns. A similar activation pattern was observed in both hemispheres, with less activation than expected in bilateral inferior frontal gyrus. These findings support that logopenic variant of primary progressive aphasia should not be considered as a neurodegeneration starting in the left brain hemisphere, but as a syndrome characterised by asymmetric neurodegeneration of brain regions and neural networks involved in language.

PET/MRI: A luxury or a necessity? / PET/RM: ¿un lujo o una necesidad?

PET/MRI is a new multimodality technique with a promising future in diagnostic imaging. Technical limitations are being overcome. Interference between the two systems (PET and MRI) seems to have been resolved. MRI-based PET attenuation correction can be performed safely. Scan time is acceptable and the study is tolerable, with claustrophobia prevalence similar to that of MRI. Quantification with common parameters, such as Standardized Uptake Value (SUV), shows a fairly good correlation between both systems. However, PET/CT currently provides better results in scan time, scan costs, and patient comfort. Less patient radiation exposure is a big advantage of PET/MRI over PET/CT, which makes it particularly recommended in paediatric and adolescent patients requiring one or more studies. PET/MRI indications are the same as those of PET/CT, given that in cases where MRI is superior to CT, PET/MRI is superior to PET/CT. This superiority is clear in many soft tissue tumours. Moreover, it is common to perform both PET/CT and MRI in neurological diseases, as well as in some tumours, such as breast cancer. A single PET/MRI study replaces both with obvious benefit. MRI also allows other MRI-based PET corrections, such as motion or partial volume effect corrections. The better spatial resolution of MRI allows the transfer of well-defined MRI areas or small volumes of interest to PET image, in order to measure PET biomarkers in these areas. The richness of information of both techniques opens up immense possibilities of synergistic correlation between them.

Prognostic value of metabolic tumour volume and total lesion glycolysis in 18F-FDG PET/CT scans in locally advanced breast cancer staging. / Papel pronóstico del volumen metabólico tumoral y de la glucólisis tumoral total en los estudios 18F-FDG PET/TC de estadificación del cáncer localmente avanzado de mama.

OBJECTIVE: To determine whether metabolic tumour volume (MTV) and total lesion glycolysis (TLG) are able to predict recurrence risk in locally advanced breast cancer (LABC) patients. MATERIAL AND METHODS: Retrospective study of LABC patients who undertook neoadjuvant, local and adjuvant treatment and follow up. A 18F-FDG PET/CT study for initial staging was performed analysing in this study different metabolic parameters (MTV, TLG, SUVmax and SUVmed) both in the primary tumour (T) as well as in axillary nodes (N) and whole-body (WB). RESULTS: Forty females were included between January 2010-2011; follow up until January 2015 was completed. The average follow-up was 46 months. Twenty percent presented recurrence: local disease (n=2) and distant metastasis (n=6); 3 patients died (38% of the patients which recurred and 7.5% from the total). SUVmax, MTV and TLG, in T, N and WB, were higher in those patients with recurrence. The MTV and TLG parameters in the tumour (T) were related to the recurrence rate (P=.020 and P=.028, respectively); whereas SUVmax in the lymph nodes (N) was significantly related (P=.008) to the recurrence rate. The best cut-off points to predict recurrence where: MTV T ≥19.3cm3, TLG T≥74.4g and SUVmax N≥13.8, being 10-12 times more likely to recidivate when these thresholds where exceeded. Tumour grade was the only clinical-pathological variable which was related to recurrence probability (p=.035). CONCLUSIONS: In this study of LABC patients the metabolic parameters which have a better relationship with recurrence rate are: MTV and TLG in the primary tumour, SUVmax in the regional lymph node disease and whole-body PET data.

Breslow thickness and (18)F-FDG PET-CT result in initial staging of cutaneous melanoma: Can a cut-off point be established?

AIM: To establish a Breslow Thickness (BT) cut-off point for indication of PET-CT of cutaneous melanoma in early stages and evaluate its prognostic value. MATERIAL AND METHODS: Retrospective analysis of 347 PET-CT studies with diagnosis of melanoma, of which 108 were performed for initial staging. Thirty-one patients were excluded, and a final sample of 77 patients remained. A ROC curve analysis was performed to establish an optimal cut-off point. A survival analysis was performed, considering death assignable to melanoma as the main event, for the evaluation of its prognostic value. RESULTS: Forty-seven (61.04%) of all 77 patients selected were men, and 11 (14.29%) had a positive PET-CT result. Mean age was 65.17±15.00 years. The median BT in patients with a negative PET-CT result was 2.75 mm (IQR 1.83-4.50) and in the positive group 6.25 mm (IQR 5.40-7.50) (P=.0013). In the ROC curve analysis (AUC 0.804, SE 0.054), an optimal value of 5 mm BT with the following values was obtained: sensitivity 90.91%, specificity 78.79%, negative predictive value (NPV) 98.1%, positive predictive value (PPV) 41.7%, diagnostic OR 37.1, and accuracy 80.52%. Mean follow-up was 18.66±14,35 months, detecting 2/53 (3.77%) deaths in the BT<5 mm group, and 7/24 (29.17%) in the BT≥5 mm group. Survival curves between both groups were significantly different (P=.0013). CONCLUSIONS: A 5 mm cut-off point correctly distinguishes those patients with positive PET-CT from those with negative results in the early stages of cutaneous melanoma; therefore it could be included in initial staging of this subgroup of patients.

[Axillary pathologic response after neoadjuvant chemotherapy in locally advanced breast cancer with axillary involvement]. / Respuesta patológica en la axila tras quimioterapia neoadyuvante en el cáncer de mama localmente avanzado con afectación axilar.

AIM: To compare axillary involvement (N+) at initial staging in locally advanced breast cancer (LABC) with axillary lymphadenectomy histologic results after neoadjuvant chemotherapy treatment (NeoChemo). MATERIAL AND METHODS: Retrospective study between November 2011 and September 2013 of LABC cases treated with neoadjuvant chemotherapy based on docetaxel (associated with trastuzumab in HER2 positive cases and carboplatin/adriamycin in HER2 negative cases). Those clinically or radiologically suspected cases of axillary involvement were histologically confirmed. When there was no suspicion of axillary involvement, sentinel lymph node radioguided biopsy (SLNRB) was performed using intradermal injection of (99m)Tc-nanocolloid albumin prior to neoadjuvant treatment. Axillary lymphadenectomy after NeoChemo was undertaken in all cases with positive axilla. Final pathologic response was classified as complete (pCR) when there was no evidence of tumoral disease and as non-pathologic complete response (no pCR) in the opposite case. RESULTS: A total of 346 patients treated with docetaxel were reviewed, identifying 105 LABC. Axillary involvement at initial staging was detected in 70 (67%) before starting NeoChemo. From these 70, 73% (n=51) were N+ (fine needle biopsy and/or biopsy) and the remaining 19 (27%) were occult N+ detected by SLNRB. Axillary lymphadenectomy detected pCR in 56% (39/70), increasing up to 84% pCR when initial N+ status was reached using SNLB. On the other hand, when N+ was detected using fine needle biopsy/lymph biopsy, pCR was only 45%. CONCLUSION: More than 50% of women affected by locally advanced breast cancer with tumoral axillary involvement at initial diagnosis present free metastatic axilla after therapeutic neoadjuvant chemotherapy effect. This increases up to almost 90% in case of occult metastatic axilla detected with sentinel node biopsy prior starting neoadjuvant chemotherapy.

18F-FDG PET-CT imaging in the neoadjuvant setting for stages II-III breast cancer: association of loco­regional SUVmax with classical prognostic factors.

AIM: Classical prognostic and predictive factors serve to predict outcome and response to neoadjuvant treatment in stage II and III breast cancer. The purpose is to determine the relation between the SUVmax of the locoregional disease with these classical prognostic factors. METHODS: A prospective study including 43 stage II and III breast cancer patients was performed. In all the patients, two 18F-FDG PET-CT studies were performed before and after neoadjuvant chemotherapy. After this treatment, surgery and adjuvant treatment were carried out. To combine the information of the locoregional disease, the SUVmax of the lesion (tumor or abnormal lymphnodes) with the highest uptake was used. SUVmax and prognostic factors were studied with the Kruskal-Wallis non-parametric test and with the Mann-Whitney U. RESULTS: A statistically significant association between elevated SUVmax value and absence of estrogen receptors (ER) expression (16 vs.. 10; P<0.019) was found. Locorregional disease with positive HER2 phenotype had a statistically significant SUVmax value greater than Luminal A (estrogen and/or progesterone positive receptors with Ki67<15%) and B (estrogen and/or progesterone positive receptors with Ki67≥to 15%) (13.4 vs. 7.9 and 8.9; P<0.022 and P<0.024, respectively). Triple negative phenotype disease had higher SUVmax than Luminal A and B (15.4; P<0.030 and P<0.038). Positive correlation between the percentage of the Ki67 Proliferation Index and SUVmax (P<0.007) was demonstrated. High grade disease had a higher SUVmax than low grade (P<0.004). CONCLUSION: Locorregional SUVmax is associated to prognostic and predictive factors and reaffirms the utility of PET-CT as a tool in the common clinical practice.