18F-FDG PET/CT in asymptomatic patients with COVID-19: the submerged iceberg surfaces.

OBJECTIVE: The aim of this case series is to describe our experience in diagnosis and management of oncological asymptomatic patients with COVID-19 who underwent 18F-FDG PET/CT. METHODS: From March 9 to March 31, 2020, we identified 5 patients who had PET/CT findings suspicious for COVID-19, but no symptom of infection. RESULTS: The first three patients were administered an SARS-CoV-2 test in a COVID-dedicated center, while the fourth and fifth were tested in our institution, in accordance with a new internal procedure. The SARS-CoV-2 test yielded positive results in all five patients. CONCLUSION: In this COVID-19 emergency, our task as radiologists and nuclear medicine physicians is to be able to identify imaging findings suggestive of the disease and to manage patients without overloading the hospital system.

PET/CT with Fluorodeoxyglucose During Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer.

OBJECTIVE: The aim of the present study is to evaluate the accuracy of Positron Emission Tomography/Computed Tomography (PET/CT) with Fluorodeoxyglucose ([18F]FDG) to predict treatment response in patients with locally advanced rectal cancer (LARC) during neoadjuvant chemoradiotherapy. PATIENTS AND METHODS: Forty-one LARC patients performed [18F]FDG-PET/CT at baseline (PET0). All patients received continuous capecitabine concomitant to radiotherapy on the pelvis, followed by intermittent capecitabine until two weeks before curative surgery. [18F]FDG-PET/CT was also carried out at 40 Gy-time (PET1) and at the end of neoadjuvant therapy (PET2). PET imaging was analysed semi-quantitatively through the measurement of maximal standardised uptake value (SUVmax) and the tumour volume (TV). Histology was expressed through pTNM and Dworak tumor regression grading. Patients were categorised into responder (downstaging or downsizing) and non-responder (stable or progressive disease by comparison pretreatment parameters with clinical/pathological characteristics posttreatment/after surgery). Logistic regression was used to evaluate SUVmax and TV absolute and percent reduction as predictors of response rate using gender, age, and CEA as covariates. Progression-free survival (PFS) and overall survival (OS) were estimated by the Kaplan-Meier method. Survivals were compared by the Log-Rank test. RESULTS: Twenty-three responders (9 ypCR, 14 with downstaged disease) and 18 non-responders showed differences in terms of both early and posttreatment SUVmax percent reduction (median comparison: responder = 63.2%, non-responder = 44.2%, p = 0.04 and responder = 76.9%, non-responder = 61.6%, p = 0.06 respectively). The best predictive cut-offs of treatment response for early and posttreatment SUVmax percent reduction were ≥57% and ≥66% from baseline (p = 0.02 and p = 0.01 respectively). CONCLUSIONS: [18F]FDG-PET/CT is a reliable technique for evaluating therapy response during neoadjuvant treatment in LARC, through a categorical classification of the SUV max reduction during treatment.

Combining standardized uptake value of FDG-PET and apparent diffusion coefficient of DW-MRI improves risk stratification in head and neck squamous cell carcinoma.

OBJECTIVES: To assess the independent prognostic value of standardized uptake value (SUV) and apparent diffusion coefficient (ADC), separately and combined, in order to evaluate if the combination of these two variables allows further prognostic stratification of patients with head and neck squamous cell carcinomas (HNSCC). METHODS: Pretreatment SUV and ADC were calculated in 57 patients with HNSCC. Mean follow-up was 21.3 months. Semiquantitative analysis of primary tumours was performed using SUVmaxT/B, ADCmean, ADCmin and ADCmax. The prognostic value of SUVmaxT/B, ADCmean, ADCmin and ADCmax in predicting disease-free survival (DFS) was evaluated with log-rank test and Cox regression models. RESULTS: Patients with SUVmaxT/B ≥5.75 had an overall worse prognosis (p = 0.003). After adjusting for lymph node status and diameter, SUVmaxT/B and ADCmin were both significant predictors of DFS with hazard ratio (HR) = 10.37 (95 % CI 1.22-87.95) and 3.26 (95 % CI 1.20-8.85) for SUVmaxT/B ≥5.75 and ADCmin ≥0.58 × 10-3 mm2/s, respectively. When the analysis was restricted to subjects with SUVmaxT/B ≥5.75, high ADCmin significantly predicted a worse prognosis, with adjusted HR = 3.11 (95 % CI 1.13-8.55). CONCLUSIONS: The combination of SUVmaxT/B and ADCmin improves the prognostic role of the two separate parameters; patients with high SUVmaxT/B and high ADCmin are associated with a poor prognosis. KEY POINTS: • High SUV maxT/B is a poor prognostic factor in HNSCC • High ADC min is a poor prognostic factor in HNSCC • In patients with high SUV maxT/B , high ADC min identified those with worse prognosis.

Positron emission tomography in the diagnostic work-up of screening-detected lung nodules.

Low-dose computed tomography (CT) screening for lung cancer can reduce lung cancer mortality, but overdiagnosis, false positives and invasive procedures for benign nodules are worrying. We evaluated the utility of positron emission tomography (PET)-CT in characterising indeterminate screening-detected lung nodules. 383 nodules, examined by PET-CT over the first 6 years of the COSMOS (Continuous Observation of Smoking Subjects) study to diagnose primary lung cancer, were reviewed and compared with pathological findings (surgically-treated patients) or follow-up (negative CT for ⩾2 years, considered negative); 196 nodules were malignant. The sensitivity, specificity and accuracy of PET-CT for differentially diagnosing malignant nodules were, respectively, 64%, 89% and 76% overall, and 82%, 92% and 88% for baseline-detected nodules. Performance was lower for nodules found at repeat annual scans, with sensitivity ranging from 22% for nonsolid to 79% for solid nodules (p=0.0001). Sensitivity (87%) and specificity (73%) were high for nodules ⩾15 mm, better (sensitivity 98%) for solid nodules ⩾15 mm. PET-CT was highly sensitive for the differential diagnosis of indeterminate nodules detected at baseline, nodules ⩾15 mm and solid nodules. Sensitivity was low for sub-solid nodules and nodules discovered after baseline for which other methods, e.g. volume doubling time, should be used.

Screening-detected lung cancers: is systematic nodal dissection always essential?

BACKGROUND: To address whether systematic lymph node dissection is always necessary in early lung cancer, we identified factors predicting nodal involvement in a screening series and applied them to nonscreening-detected cancers. METHODS: In the 97 patients with clinical T1-2N0M0 lung cancer (<3 cm), enrolled in the Continuous Observation of Smoking Subjects computed tomography (CT) screening study, who underwent curative resection with radical mediastinal lymph node dissection, we examined factors associated with hilar extrapulmonary and mediastinal nodal involvement. Nodule size plus positive/negative positron emission tomography (PET)-CT (usually as maximum standard uptake value [maxSUV]) were subsequently evaluated retrospectively for their ability to predict nodal involvement in 193 consecutive patients with nonscreening-detected clinical stage I lung cancer. RESULTS: Among Continuous Observation of Smoking Subjects patients, 91 (94%) were pN0, and six (6.2%) were pN+. All patients with maxSUV <2.0 (p = 0.08) or pathological nodule ≤10 mm (p = 0.027) were pN0 (62 cases). Nodal metastases occurred in 6 cases among the 29 (17%) patients with lung nodule >10 mm and maxSUV ≥2.0 (p = 0.002 versus the other 62 cases). In the nonscreening series, 42 of 43 cases with negative PET-CT (usually maxSUV <2.0) or nodule ≤10 mm were pN0; 33 of 149 (22%) cases with positive PET-CT (usually maxSUV ≥ 2.0) and nodule >10 mm were pN+ (p = 0.001 versus the 43 cases). CONCLUSIONS: This limited experience suggests that in early-stage clinically N0 lung cancers with maxSUV <2.0 or pathological nodule size ≤10 mm, systematic nodal dissection can be avoided as the risk of nodal involvement is very low.

Lymph node involvement in T1 non-small-cell lung cancer: could glucose uptake and maximal diameter be predictive criteria?

OBJECTIVE: The introduction of modern staging systems such as computed tomography (CT) and positron emission tomography/CT (PET/CT) with fluorodeoxyglucose ([(18)F]FDG) has increased the detection of small peripheral lung cancers at an early stage. We analyzed the behavior of pathological T1 non-small-cell lung cancer (NSCLC) to identify criteria predictive of nodal involvement, and the role of cancer size in lymph node metastases. METHODS: We retrospectively analyzed 219 patients with pathological T1 NSCLC. All patients were staged by high-resolution CT and PET as stage I, and underwent anatomical resection and radical lymphadenectomy. Our data were collected based on pathological nodule size (0-10 mm; 11-20 mm; and 21-30 mm); morphological features of lung nodule and FDG uptake of the tumor measured by standardized uptake value (SUV). RESULTS: A total of 190 patients (87%) were pN0, 14 (6%) pN1, and 15 (7%) pN2. No nodal involvement was observed in any of the 62 patients with nodule size less than 10 mm, in 20 out of 120 patients (17%) with nodule size 11-20 mm, and in nine out of 37 tumors (28%) 21-30 mm in size (p=0.0007). All 55 patients with nodule SUV<2.0 and all 26 non-solid lesions were pN0 (respectively, p=0.0001 and p=0.03). All nodal metastases occurred among the group of 132 patients with size larger than 10 mm and SUV higher than 2.0 with a 22% rate of nodal involvement of (29 patients) (p<0.0001). CONCLUSIONS: The low probability of lymph node involvement in NSCLC <1 cm or showing glucose uptake <2 suggests lymphadenectomy could be avoided. A randomized trial should be performed to validate our data.

Sentinel node detection by lymphoscintigraphy and sentinel lymph node biopsy in vulvar melanoma.

PURPOSE: Vulvar melanoma is a rare malignant tumour. Its surgical excision is the mainstay of treatment whilst the surgical management of regional lymph nodes remains controversial; on the contrary elective inguinofemoral lymphadenectomy causes considerable morbidity. Lymphoscintigraphy (LS) and sentinel lymph node biopsy (SLNB) are accurate staging procedures of lymph node status in breast cancer and cutaneous melanoma patients. In this retrospective paper we report our experience of LS and SLNB in vulvar melanoma patients. METHODS: Twenty-two consecutive patients with a diagnosis of vulvar melanoma were treated at our institute: patients with clinically positive groin nodes or with previous surgery on the primary tumour were excluded. Twelve were selected for our analysis. All patients underwent sentinel lymph node localization with LS the day before surgery and the surgical procedure of SLNB associated with radical surgery. RESULTS: Six patients had metastatic SLNB and in five of six (83.3%) it was the only positive node. In the other six patients SLNB was negative for metastatic disease. No skip metastases were observed. In SLNB negative patients the mean Breslow thickness was 2.06 mm (range: 0.60-7.10) and only one patient showed a high Breslow thickness (patient 8). In SLNB positive patients the mean Breslow thickness was 4.33 mm (1.8-6.0). CONCLUSION: Our data indicate that, even in vulvar melanoma, the sentinel lymph node pathological status predicts the pathological status of the remaining groin nodes and suggests that elective groin dissection can be spared in cases of a negative SLNB. Breslow thickness (<1 mm) was not predictive of negative nodes.

Modification of lymphoscintigraphic sentinel node identification before and after excisional biopsy of primary cutaneous melanoma.

The aim of this study was to determine whether excision biopsy and primary closure of primary cutaneous melanoma modifies lymphatic drainage and accuracy of sentinel node biopsy. Thirty patients with 31 cutaneous melanomas were prospectively enrolled to undergo lymphoscintigraphy (LS) before and after excision biopsy. Tc-human serum albumin nanocolloid was first injected intradermally around the primary tumor and subsequently, after excision biopsy, adjacent to the scar. Sentinel nodes were identified by preoperative LS and the gamma-probe. Patent Blue V dye was injected intraoperatively before sentinel node biopsy. Intraoperative sentinel node identification was 100%. In 23 of 31 cases, both LSs were concordant in terms of nodal basins visualized. Two patients had a basin downstaged and six patients had a basin upstaged by the second LS. Only 50% of LS hot nodes stained blue (42 of 84). In 24 of 31 cases, the sentinel node was negative for metastases. Seven patients underwent complete lymph node dissection because of sentinel node positivity. Only one patient had metastases also to a non-sentinel node. After a median follow-up of 30 months lymph node metastases have not been observed in the eight discordant cases. This study shows that sentinel node identification and biopsy after lymphatic mapping is accurate after excision biopsy of primary cutaneous melanoma. Excision biopsy may, however, modify lymphatic drainage and a narrow excision margin should be performed if melanoma is suspected.

[18F]FDG positron emission tomography/computed tomography and multidetector computed tomography roles in thymic lesion treatment planning.

RATIONALE: Thymic masses may represent an unsolved diagnostic problem which often require surgical procedures for an accurate staging. A non-invasive way to determine the nature of thymic lesions would help identify the patients which are true candidates for surgery. Our retrospective study aims to assess multidetector computed tomography and 2-[(18)F]fluoro-2-deoxyglucose positron emission tomography/computed tomography ([(18)F]FDG-PET/CT) capacity to distinguish benign from malignant thymic lesions. METHODS: Helical multidetector CT (MDCT) and [(18)F]FDG-PET/CT of twenty consecutive patients presenting with a thymic mass at our Institute were retrospectively analyzed. MDCT scans were focused on morphologic features and invasiveness characteristics. Qualitative and semi-quantitative analyses by maximum standardized uptake value corrected for body weight (SUVbw max) were performed on [(18)F]FDG-PET/CT. In all cases, readers were blinded to pathology findings. Both imaging techniques were correlated to final pathology. Student's t-test was performed on SUVbw max stratified for thymic epithelial tumors. RESULTS: In the group of benign lesions MDCT correctly identified well-defined margins of masses in 8 out of 8 patients whereas [(18)F]FDG-PET/CT was negative in 7 out of 8 patients. Among malignant lesions MDCT revealed mediastinum fat or infiltration of adjacent organs in 10/12 patients. On the other hand [(18)F]FDG-PET/CT showed increased radiotracer uptake in 12/12 patients. CONCLUSIONS: MDCT and [(18)F]FDG-PET/CT alone are not able to differentiate the nature of thymic lesions. However, they are two non-invasive complementary techniques which can be used to differentiate benign from high-risk malignant thymic lesions. These findings should be taken into account before surgery is performed as a diagnostic procedure.

Role of [18F]FDG-PET/CT after radiofrequency ablation of liver metastases: preliminary results.

PURPOSE: Focal metastasis may be treated with radiofrequency ablation (RFA), a low invasive method yet limited by the lack of direct evidence of radicality of treatment. We, hereby, aimed at assessing the role of positron emission tomography-computed tomography (PET/CT) with fluoride radiolabeled deoxy-glucose ([(18)F]FDG) in RFA treatment success evaluation and early diagnosis of local relapse of liver metastasis after RFA procedure. METHODS: RFA was performed in nine patients on 12 liver metastasis, serially imaged through [(18)F]FDG-PET/CT and multidetector CT (MDCT) at 1, 3, 6, and 9 months after treatment. Eight lesions were also scanned with [(18)F]FDG-PET/CT at 1 week after treatment. Imaging analyses were performed on 47 [(18)F]FDG-PET/CT and 51 MDCT. Imaging reading outcomes were compared to each other and to biopsy tissue results when available. RESULTS: In one case, [(18)F]FDG-PET/CT revealed radiotracer uptake at RFA site a week after procedure. Negative concordant outcome was obtained on eight lesions at 1 month after RFA, on eight cases at 3 months, on four at 6 months, and on two cases at 9 months. Extra-liver (peritoneal) disease was detected in one case by both [(18)F]FDG-PET/CT and MDCT. In seven cases, [(18)F]FDG-PET/CT revealed the presence of local recurrence earlier than MDCT. In no cases did MDCT detect local relapse earlier than [(18)F]FDG-PET/CT. CONCLUSION: [(18)F]FDG-PET/CT may detect RFA treatment failure as well as local relapse after RFA earlier than MDCT.