PET/CT and Conventional Imaging for the Assessment of Neuroendocrine Prostate Cancer: A Systematic Review.

BACKGROUND: Neuroendocrine prostate cancer (NEPC) is a rare neoplasm, and the role of both conventional imaging (CI) and positron emission tomography/computed tomography (PET/CT) for its assessment has not been clearly evaluated and demonstrated. The aim of this systematic review was to analyze the diagnostic performances of these imaging modalities in this setting. METHODS: A wide literature search of the PubMed/MEDLINE, Scopus, and Web of Science databases was made to find relevant published articles about the role of CI and PET/CT for the evaluation of NEPC. RESULTS: 13 studies were included in the systematic review. PET/CT imaging with different radiopharmaceuticals has been evaluated in many studies (10) compared to CI (3 studies), which has only a limited role in NEPC. Focusing on PET/CT, a study used [18F]FDG, labeled somatostatin analogs were used in 5 cases, a study used [68Ga]Ga-FAPI-04, [68Ga]Ga-PSMA-11 was evaluated in a single case, and two works used different tracers. CONCLUSION: Published data on the role of PET/CT for the assessment of NEPC are limited. At present, it is still uncertain which tracer performs best, and although [18F]FDG has been evaluated and seems to offer some advantages in availability and clinical staging, other tracers may be more useful to understand tumor biology or identify targets for subsequent radioligand therapy. Further research is therefore desirable. In contrast, data are still limited to draw a final conclusion on the role and the specific characteristics of CI in this rare form of neoplasm, and therefore, more studies are needed in this setting.

New criteria for the diagnosis of infective endocarditis using 18F-FDG PET/CT imaging.

OBJECTIVES: The purpose of this study was to examine a qualitative scoring system and a semi-quantitative method of FDG-PET/CT imaging in the diagnosis of infective endocarditis (IE). METHODS: We retrospectively included 108 patients who underwent 18F-FDG-PET/CT for suspected IE. PET/CT scans were interpreted using a 4-point score (0 = no uptake; 1 = cardiac uptake < blood-pool activity; 2 = blood-pool < uptake < liver activity; 3 = uptake > liver) and semi-quantitatively using SUVmax and SUVmean of the suspected valve lesion, liver, spleen, and of the bone marrow (BM). BM and spleen SUVmean were normalized to the liver, and hypermetabolism (HSBM) was defined as a BM or spleen-to-liver ratio > 1. RESULTS: Comparing the score criteria results with the clinical final diagnosis, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of qualitative criteria were 93%, 81%, 84%, 91%, and 87%, respectively. A definite IE was documented in 83% of patients showing HSBM and abnormal cardiac uptake, 44% with abnormal cardiac uptake, 28% with HSBM, and 10% with neither one. CONCLUSION: The qualitative scoring system is helpful in the diagnosis of IE. The HSBM is an additional, reliable indirect sign of IE.

Incidental Findings Suggestive of COVID-19 in Asymptomatic Patients Undergoing Nuclear Medicine Procedures in a High-Prevalence Region.

Infection with the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may remain asymptomatic, leading to under-recognition of the related disease, coronavirus disease, 2019 (COVID-19), and to incidental findings in nuclear imaging procedures performed for standard clinical indications. Here, we report about our local experience in a region with high COVID-19 prevalence and dynamically increasing infection rates. Methods: Within the 8-d period of March 16-24, 2020, hybrid imaging studies of asymptomatic patients who underwent 18F-FDG PET/CT or 131I SPECT/CT for standard oncologic indications at our institution in Brescia, Italy, were analyzed for findings suggestive of COVID-19. The presence, radiologic features, and metabolic activity of interstitial pneumonia were identified, correlated with the subsequent short-term clinical course, and described in a case series. Results: Six of 65 patients (9%) who underwent PET/CT for various malignancies showed unexpected signs of interstitial pneumonia on CT and elevated regional 18F-FDG avidity. Additionally, 1 of 12 patients who received radioiodine for differentiated thyroid carcinoma also showed interstitial pneumonia on SPECT/CT. Five of 7 patients had subsequent proof of COVID-19 by reverse-transcriptase polymerase chain reaction. The remaining 2 patients were not tested immediately but underwent quarantine and careful monitoring. Conclusion: Incidental findings suggestive of COVID-19 may not be infrequent in hybrid imaging of asymptomatic patients in regions with an expansive spread of SARS-CoV-2. Nuclear medicine services should prepare accordingly.

131I Whole-Body Scan Incidental Uptake Due to Spermatocele.

A 46-year-old man with papillary thyroid cancer post total thyroidectomy was referred for post radioiodine (I) whole-body scan. Whole-body images revealed intense I uptake in the bed thyroid and a focal abnormal uptake in the testicular area. Subsequent SPECT/CT demonstrated that the focal uptake corresponded to the left epididymis, and the pathology report revealed a spermatocele with no immunohistochemical features for thyroid tissue. Many cases of unexpected radioiodine uptake have been reported, and spermatocele could be counted for another possibility of incidental I uptake despite an unclear mechanism.

Positron Emission Tomography/Computed Tomography for the Pleural Staging of Malignant Pleural Mesothelioma: How Accurate Is It?

BACKGROUND: Careful clinical staging in patients with malignant pleural mesothelioma (MPM) is fundamental in management planning. Positron emission tomography/computed tomography (PET/CT) is increasingly recognized as an important staging modality. OBJECTIVES: The purpose of this study was to assess whether the metabolic activity of the pleural tumor detected with PET/CT correlates with specific endoscopic features and pleural distribution of the lesions as assessed by medical thoracoscopy. METHODS: Consecutive patients with MPM and available PET/CT performed before thoracoscopy were separated into 2 groups, according to their standardized uptake value (SUV). Kaplan-Meier-analysis for survival was performed on groups with low and high SUV. Agreement between PET/CT and thoracoscopy evaluation was analyzed using Cohen's kappa coefficient. The Wilcoxon test was used to compare the median SUV, and the χ(2) test was used to evaluate differences in endoscopic findings. RESULTS: A total of 32 patients were included. The median maximum SUV (SUV max) was 6.1 and patients were separated into 2 groups based on this cutoff. Patients with SUV max <6.1 had a better survival than those with SUV max ≥6.1 (p = 0.005). The comparison between PET/CT and thoracoscopy showed a fair agreement for visceral and diaphragmatic pleural involvement and moderate agreement for the presence of nodular lesions. There was a statistically significant association between median SUV max and visceral pleural involvement; nodular lesions and visceral pleural involvement were more common in the high-SUV group than in the low-SUV group (p = 0.0012 and p = 0.03, respectively). CONCLUSIONS: PET/CT data may be predictive of thoracoscopic features of MPM associated with prognosis and staging, but the correlation is moderate at best. A degree of disagreement exists between these two modalities, which supports thoracoscopy as the gold standard for assessment of local invasion in MPM.

Absence of urine production due to renal failure enables clear visualization of primary urinary bladder carcinoma on 18F-FDG PET/CT.

An 81-year-old man affected by renal failure, underwent 18F-FDG PET/CT for detecting primary lesion because of multiple lung nodules consistent with secondary lesions revealed by computed tomography without contrast. PET study documented high pathologic uptake at anterior and upper wall of urinary bladder, and a primary urinary bladder cancer was suspected. Biopsy confirmed the presence of a high-grade transitional cell carcinoma.

Possible role of F18-FDG-PET/CT in the diagnosis of endocarditis: preliminary evidence from a review of the literature.

Infective endocarditis (IE) is a particular disease which presents with a variety of clinical, aetiological forms and is lethal if not aggressively treated with antibiotics alone or in combination with surgery. This review tries to analyse the possible role of F18-FDG-PET/CT in the diagnosis of IE based on the state of art in literature.

The value of attenuation correction by hybrid SPECT/CT imaging on infarct size quantification in male patients with previous inferior myocardial infarct.

BACKGROUND: Attenuation correction (AC) has been shown to improve the accuracy of myocardial perfusion single photon emission computed tomography (SPECT) for the detection and evaluation of patients with coronary artery disease. Attenuation artifacts, because of diaphragmatic attenuation, frequently affect the evaluation of the inferior wall, especially in male patients. PURPOSE: The aim of this study was to evaluate the value of AC for the assessment of infarct size in coronary artery disease patients after inferior myocardial infarction. MATERIALS AND METHODS: Gated-SPECT with Tc-labeled compounds with AC by hybrid SPECT/computed tomography (CT) was performed in 56 male patients with documented previous inferior myocardial infarction. Both corrected and uncorrected SPECT images were processed after motion and scatter correction by ordered-subset expectation maximization iterative reconstruction. When needed, a manual realignment between SPECT and computed tomography (CT) sections was performed. Uncorrected and corrected SPECT images were analyzed for perfusion using a 5-point segmental scoring scale from 0 (normal) to 4 (absent). Summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) of the inferior left ventricle wall (inferoseptal, inferior, infero-apical and infero-lateral segments) were determined and compared with the regional wall motion score as determined by uncorrected gated-SPECT. RESULTS: The SSS, SRS, SDS for attenuation-uncorrected and attenuation-corrected studies were 14.02 ± 7.9, 9.51 ± 7, 4.5 ± 3.2 and 9.39 ± 7.1, 5.6 ± 6.1, 3.8 ± 2.8, respectively. Differences were statistically significant (P<0.0001) for SSS and SRS but not for SDS. The regional summed rest score of the inferior wall (SRS of inferior segments) showed a better correlation with the regional summed wall motion score of the same segments: R²=0.50 in comparison to uncorrected SRS, R²=0.46. CONCLUSION: The combination of diaphragmatic attenuation and inferior myocardial infarction determines an artifactual overestimation of infarct size of inferior infarcts. The AC regional perfusion score (SRS) correlates with the regional wall motion score of the inferior wall. AC does not affect the detection and size of residual ischemia (SDS).

Financial and clinical implications of low-energy CT combined with 99m Technetium-sestamibi SPECT for primary hyperparathyroidism.

BACKGROUND: (99m)Technetium-sestamibi hybrid SPECT/CT has been favored over conventional SPECT in preoperative evaluation of primary hyperparathyroidism (PHPT) patients. However, the financial implications of CT-image acquisition have never before been published. This prompted us to perform a cost analysis of the aforementioned nuclear procedures. METHODS: A total of 55 PHPT patients operated on between 2004 and 2009 were studied. Overall, 27 patients underwent SPECT and 28 SPECT/CT. Localization results, as well as diagnostic and clinical cost variations between SPECT and SPECT/CT patients, were compared. RESULTS: SPECT/CT revealed higher sensitivity than SPECT (96.7 vs 79.3%; P = .011), as well as higher specificity (96.4 vs 82.4%; P = .037) and positive predictive value (PPV) (96.7 vs 83%; P = .038) for correctly identifying the neck-side affected by PHPT. Likewise, SPECT/CT disclosed higher sensitivity (86.7 vs 61.1%; P < .0001), specificity (97.4 vs 90%; P = .022), and PPV (86.7 vs 65.7%; P = .0001) for correct neck-quadrant identification. The mean operative time decreased from 62 min following SPECT to 36 min following SPECT/CT (P < .0001), yielding a mean surgical expense saving of 109.9 /patient (updated at 2009/2010 billing database). SPECT/CT actually ensures a mean expenditure reduction of 98.7 /patient (95% CI: 47.96 -149.42 ), diagnostic costs variation amounting to 11.2 /procedure. CONCLUSIONS: SPECT/CT ensures better focus for the surgical exploration, shortens surgical times, and eventually cuts costs when used for localization of parathyroid adenomas.

CSF Alzheimer's disease-like pattern in corticobasal syndrome: evidence for a distinct disorder.

BACKGROUND: Corticobasal syndrome (CBS) has a heterogeneous neuropathological spectrum, ranging from the classical corticobasal degeneration to Alzheimer's disease (AD). The neuropathology of CBS is still unpredictable. CSF tau/abeta ratio is a reliable marker of AD. OBJECTIVE: To evaluate the presence of a distinct clinical and neuroimaging CBS phenotype according to CSF pattern. METHODS: 30 patients fulfilling current clinical criteria for CBS entered the study. Each patient underwent a clinical and standardised neuropsychological assessment, and CSF analysis (total tau and abeta42 dosages). CSF AD-like pattern and CSF non-AD like pattern (nAD-like) were identified. In 23 CBS cases, (99m)Tc-ECD single photon emission computed tomography (SPECT) scan was performed and analysed by statistical parametric mapping. RESULTS: CSF AD-like pattern was reported in six cases (20%). The two subgroups did not differ in demographic characteristics or global cognitive impairment. The AD-like group showed greater impairment of memory performances, language and psychomotor speed while the nAD-like group had more severe extrapyramidal syndrome with comparable apraxia scores. Voxel by voxel analysis on SPECT images demonstrated that CBS AD-like patients had greater hypoperfusion in the brain areas typically affected by AD-namely, precuneus, posterior cingulate and hippocampus, bilaterally-compared with nAD-like patients (p<0.001). No clusters above the pre-established threshold were detected when nAD-like were compared with AD-like patients. CONCLUSIONS: CSF AD-like profile in CBS is associated with earlier memory impairment and brain abnormalities typically found in classical AD. These findings argue for the usefulness of CSF testing to identify AD in CBS, and might suggest a different pharmacological approach on the basis of biological data.

F18-FDG-PET/CT in a patient affected by Lynch syndrome.

Lynch syndrome (LS) is the most common hereditary syndrome that predisposes patients to colorectal cancer, and it accounts for 2-5% of the total burden of colorectal cancer. We report a case of a 61-year-old female affected by Lynch syndrome who underwent multiple adenocarcinoma resections, studied by F18-FDG-PET/CT for 5 years. This case report suggests a potential role of F18-FDG-PET/CT in the evaluation of patients affected by Lynch syndrome.

F-18 FDG-PET/CT evaluation of patients with differentiated thyroid cancer with negative I-131 total body scan and high thyroglobulin level.

PURPOSE: The aim was to evaluate the incremental diagnostic rate of F-18 fluoro-fluorodeoxygulose positron emission tomography/computed tomography (F-18 FDG-PET/CT) in patients with negative I-131 whole body scans and high Tg levels. The secondary end points were correlations between F-18 FDG-PET/CT positive results and Tg levels and comparison between F-18 FDG-PET/CT accuracy in patients "on-therapy" with suppressed thyroid stimulating hormone (TSH) and those with high TSH levels. METHODS: We studied 52 patients who had undergone total thyroidectomy and remnant ablation; they had high Tg levels (average = 156 ng/mL; SD +/- 274) after 3 weeks of levothyroxine withdrawal and negative I-131 total body scans after therapeutic doses. RESULTS: We noted a statistically significant positive correlation between F-18 FDG-PET/CT positive results and Tg levels, irrespective of levothyroxine therapy regimen. Tg levels between F-18 FDG-PET/CT positive/negative groups were significantly different and we did not note any statistically significant correlation between F-18 FDG-PET/CT results and TSH levels, tumor size, and combination of Tg/TSH levels. CONCLUSIONS: Our results indicate that F-18 FDG-PET/CT is a useful diagnostic tool in patients with differentiated thyroid carcinoma and with negative I-131 total body scans and high Tg levels. The levothyroxine therapy regimen does not influence F-18 FDG-PET/CT results and the rate of F-18 FDG-PET/CT positive results appears to correlate with the Tg levels. The highest accuracy is reached when the study is performed for patients with Tg levels higher than 21 ng/mL.

A patient with medullary thyroid carcinoma and right ventricular cardiac metastasis treated by (90)Y-Dotatoc.

Medullary thyroid carcinoma (MTC) is rare derived from C cells of the thyroid gland and represents approximately 5% of all thyroid carcinomas. We report a case of a 74 years old male with MTC, diagnosed in 2002 and treated with total thyroidectomy and lymphadenectomy. A metastatic lesion was diagnosed on the right ventricle by indium-111-octreoscan, fluorine-18-fluorodeoxyglucose-positron emission tomography/computerized tomography, echocardiography, magnetic resonance imaging, high resolution computed tomography and was confirmed by histopathology. We present the results of treatment of this patient with yttrium-90-DOTA-tyr(3)-octreotide.

Residual brain viability, evaluated by (99m)Tc-ECD SPECT, in patients with suspected brain death and with confounding clinical factors.

BACKGROUND: In 1968, the Harvard criteria for brain death diagnosis were introduced in clinical practice. These include no movements or breathing, no reflexes, and flat electroencephalogram in the absence of confounding factors, including hypothermia, drugs, electrolyte, and endocrine disturbances. When confounding factors occur, confirmatory tests documenting the absence of cerebral blood flow, such as cerebral angiogram, transcranial Doppler sonography, computed tomography angiography, and nuclear techniques, are required. AIM: The aim of this study was to evaluate the clinical value of single-photon emission computed tomography (SPECT) with technetium-99m (Tc)-ECD in the diagnosis of brain death in a cohort of patients with confounding factors. Fifty-two patients were studied between 1 January 2000 and 23 September 2008. The criteria for the request for Tc-ECD SPECT were sodic thiopental withdrawal after less than 24 h, unreceptivity and unresponsivity of brainstem reflexes, anesthesia in the last 24 h, hypothermia, anamnesis for barbiturate use, electroencephalogram artefacts, toxic state, and pediatric criteria. All patients underwent Tc-ECD SPECT using a dual-headed camera fitted with a high-resolution low-energy collimator. Images were reconstructed and processed according to standard procedures and interpreted qualitatively by two experienced observers. RESULTS: The presence of spots of residual brain viability was observed in 13 patients: 25% of our patient cohort. The patients with residual viability were younger (aged 30.92+/-17.28 years) in comparison with those with no viability (41.91+/-18.77 years, P<0.031). Considering the eligibility for transplantation, there were 12 of 13 patients in the residual viability group and 31 of 39 in the no viability group (P<0.0001). All patients with spots of brain uptake were monitored daily by Tc-ECD SPECT, and all of them reached the condition of empty skull after one or multiple studies. The opposition to organ donation was observed in six of 13 patients with spots of viable brain tissue and in three of 39 with no signs of residual viability (P<0.001). CONCLUSION: In patients with confounding factors in whom brain death diagnosis is equivocal, Tc-ECD SPECT is a helpful and safe diagnostic approach, allowing a three-dimensional evaluation of cortical and brainstem viability. It guarantees an unequivocal diagnosis of brain death for patients who are potential candidates for organ donation. The persistence of viable spots of brain tissue was found in 25% of our patients and was more frequent in young patients. This affects the opposition to donation.