Controversy in the initial nodal staging of rectal cancer (MRI or PET/CT?)

OBJECTIVE

To compare the usefulness of MRI and PET/CT in nodal staging (N) of patients with locally advanced rectal cancer (LARC).

MATERIAL AND METHODS

Retrospective study of patients with LARC, who completed their initial staging with PET/CT, between January-20 and March-23. Regional nodes were assessed, and N was determined using both techniques according to TNM criteria. Concordance between MRI and PET/CT was analyzed. The accuracy of both techniques was calculated for those patients who underwent direct surgery. Non-regional pelvic lymph nodes were evaluated by both modalities.

RESULTS

Among the 73 patients, 48 were ultimately diagnosed with a locally advanced stage. Of these, 39 underwent neoadjuvant treatment (chemoradiotherapy) followed by surgery, and 9 direct surgery. In 25, the PET/CT extension study revealed distant disease, leading to systemic treatment. Weak concordance was observed between MRI and PET/CT in determining N (k=0.286; p<0.005). Out of 73 patients, 31(42%) exhibited concordance, and 42(58%) showed discordance. In 83% of the discordant cases, MRI overstaged compared to PET/CT, with 17 cases indicating nodal involvement (N+) by MRI and N0 by PET/CT. Diagnostic accuracy was 78% for both techniques. Sensitivity, specificity, positive predictive value, and negative predictive value were 80%, 75%, 80%, and 75% for MRI, and 60%, 100%, 100%, and 67%, for PET/CT. PET/CT identified pelvic metastatic adenopathies in 8 patients that were not visible/doubtful by MRI.

CONCLUSIONS

In the initial nodal staging of rectal cancer MRI overstages relative to PET/CT. Both modalities are complementary, PET/CT offers higher specificity and MRI higher sensitivity.

Decoding polymyalgia rheumatica, the role of Nuclear Medicine Imaging

Polymyalgia rheumatica (PMR) is an inflammatory joint disease that presents in patients older than 50 years with prolonged morning pain and stiffness in the shoulder and hip joints and neck. The lack of specific clinical findings, laboratory signs, biomarkers and established imaging methods makes it difficult to diagnose patients with this disease. 18F-FDG PET/CT is a functional imaging technique that is an established tool in oncology and has also proven useful in the field of inflammatory diseases. The aim of this paper is to present literature evidence on the use of molecular imaging methods such as PET/CT for early diagnosis, assessment of disease activity and therapeutic response in PMR. At the same time, the advantages, disadvantages and contraindications of other methods are considered.

Primary tumor heterogeneity on pretreatment 18F-FDG PET/CT to predict outcome in patients with rectal cancer who underwent surgery after neoadjuvant therapy

PURPOSE

This retrospective study aimed to investigate the value of texture features of primary tumors in pretreatment ¹⁸F-FDG PET/CT in the prediction of response to treatment, progression, and overall survival in patients with rectal cancer who underwent surgery after neoadjuvant therapy(NAT).

METHODS

Patients with rectal cancer who had pretreatment ¹⁸F-FDG PET/CT, and underwent surgery after NAT were included in this study. Clinicopathologic features, date of last follow-up, progression, and death were recorded. Textural and conventional PET parameters(maximum standardized uptake value-SUVmax, metabolic tumor volume-MTV, total lesion glycolysis-TLG) were obtained from PET/CT images using LifeX program. Parameters were grouped using Youden index in ROC analysis. Factors predicting the pathological response to treatment, progression, and overall survival were determined using logistic regression and Cox regression analyses.

RESULTS

Forty-four patients (26(59%) male, 18(41%) female; 60.1±11.4 years) with rectal cancer were included in this study. The numbers of patients with responders and non-responders to NAT were 15(34.9%) and 28(65.1%), respectively. One patient' pathology report did not contain the response status to NAT. The median of follow-up duration was 29.9 months. 9(20.5%) showed disease progression, and 8(18.2%) died during the follow-up period. Difference entropy_GLCM and correlation_GLCM parameters were found as independent predictors for response to NAT. The positivity of surgical margin, intensity interquartile range_CONV and AUC-CSH_DISC texture parameters were independent predictors of progression, while normalized inverse difference_GLCM and LZLGE_GLZLM parameters were independent predictors of mortality.

CONCLUSION

The texture parameters obtained from pretreatment ¹⁸F-FDG PET/CT have presented a more robust predictive value than conventional parameters in patients with rectal cancer who underwent surgery after NAT.

Contribution of 18F-FDG PET/CT imaging in the diagnosis and management of HIV-positive patients

INTRODUCTION AND OBJECTIVES

The human immunodeficiency virus [HIV] is a lentevirus, primarily infects certain cells of the immune system, thereby greatly weakens the body's own defenses against diseases. This study was aimed to explore the value and significance of ¹⁸F-FDG PET/CT in the assessment of patients with HIV infection and to examine the presence of quantitative alterations in ¹⁸F-FDG uptake among patients with HIV-related infections or malignant diseases in HIV-positive patients.

PATIENTS AND METHODS

Forty patients with HIV infection were scanned on PET/CT system. The data were registered according to immune status, antiretroviral therapy, and definitive diagnosis. All pathologic lesions and disease related areas were described, ¹⁸F-FDG uptake patterns were evaluated. Semiquantitative analysis of ¹⁸F-FDG uptake was performed and SUVmax were calculated.

RESULTS

Twenty-eight patients [70%] were diagnosed with HIV-related infection or malignant diseases. The sensitivity of PET/CT was shown to be 100% and the specificity 92% for concomitant diseases requiring additional treatment to antiretroviral therapy. The SUVmax and CD4 counts were not statistically different between HIV-related reactive lymphadenopathy, HIV-related malignancy, and HIV-related infections.

CONCLUSIONS

The pattern of distribution of nodal/extranodal uptake on ¹⁸F-FDG PET/CT may facilitate distinction between HIV-related generalized lymphadenopathies, HIV-related opportunistic infections, and malignancies. In this context, ¹⁸F-FDG PET/CT should be preferred for routine use in the management of patients infected with HIV.

The role of 18F-FDG PET/CT in the management of Merkel cell carcinoma: The experience of 51 studies in our institution

OBJECTIVES

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor with limited evidence on the role of ¹⁸F-FDG PET/CT. The aim of this study was to assess the impact of the ¹⁸F-FDG PET/CT in the management of MCC.

METHODS

Fifty-one studies of ¹⁸F-FDG PET/CT of 35 patients (19 men [54.30%]; 72.17±14.63years) with histologic diagnosis of MCC were retrospectively evaluated. The change in tumor staging and the impact on the treatment were analysed.

RESULTS

There were 23 PET/CT positive studies (45.10%) and 28 (54.90%) negative. Thirty four (66.7%) studies were performed for assessment of stage at initial presentation and 17 (33.3%) were performed during the follow up: 6 (35.29%) for suspected recurrence; 7 (41.18%) for restaging; 4 (23.53%) as a part of ongoing surveillance. On the basis of PET/CT results, there was a change in disease stage (SC) in 20 studies (39.20%) and impact in the management (MI) in 28 (54.90%): 11 (32.40%) SC and 12 (35.30%) MI in the initial staging; 5 (71.43%) SC and 7 (100%) MI in the restaging; 3 (50.00%) SC and 6 (100%) MI in suspected recurrence; 1 (25.00%) SC and 3 (75.00%) MI in the surveillance. ¹⁸F-FDG PET/CT incidentally detected one additional histologically confirmed cancer. The presence of nodal involvement in the beginning (0.0098; HR 3.82; 95%CI: 1.38-10.6), chemotherapy treatment (6e-04; HR 7.06; 95%CI: 2.30-21.60), size of primary tumor >2cm (6e-04; HR 7.06; 95%CI: 2.30-21.60) and positive resection margin (0.00069; HR 4.01; 95%CI: 1.46-11.00) were statistically significant prognostic factors for overall survival. There was a trend towards significance for worse overall survival with initial positive ¹⁸F-FDG PET/CT but the trend did not reach statistical significance.

CONCLUSION

¹⁸F-FDG PET/CT altered the stage in 2 out of 5 studies and changed the treatment in more than half of the studies performed. The study confirms the important impact of ¹⁸F-FDG PET/CT on the management of MCC patients.

Nuclear Medicine in the diagnosis of pathologies of the spine: role of hybrid imaging

Clinical problems in the human spine are still common in our society, often causing pain and can also limit movement. Back pain is a very common clinical entity, although difficult to diagnose due to its multifactorial nature. There are multiple processes that can alter the structure of the spine, injure vertebrae and/or the surrounding tissue. For the study of the spine, image diagnosis is essential, and within this, molecular hybrid techniques play an important role by providing us with an image of functional and morphological fusion. Among these, SPECT/CT is key in the diagnosis of traumatic and stress pathology, allowing us to locate hidden vertebral fractures, and is also very useful in degenerative and post-surgical pathology. On the other hand, PET/CT with 18F-FDG also plays an important role in the management and monitoring of infectious and oncological processes. This review describes the application of these hybrid techniques in the different pathologies of the spine and the findings of their images, being very useful for the diagnostic assessment and therapeutic management of the patient.

FDG PET/CT in colorectal cancer

Colorectal cancer is the third most frequent cancer worldwide. Although its incidence is increasing, mainly in those aged under50, mortality has decreased by 50% in the more developed countries, principally due to the adoption of new practices in prevention, diagnosis and treatment. In particular, the various diagnostic imaging modalities allow improved therapeutic decision-making, evaluation of the response and early detection of recurrence. The aim of this paper is to review the available scientific evidence on the value of positron emission tomography with ¹⁸F-FDG (¹⁸F-FDG PET/CT) in the colorectal cancer, with special emphasis on the indications of the guidelines and recommendations of the main international scientific associations regarding this imaging technique.

Different patterns of hepatocellular carcinoma-related malign thrombosis in 18F-FDG PET/CT

Tumor thrombus is an intravascular malign tumor extension that may occur in various types of cancer. Hepatocellular carcinomas (HCC) are common causes of malign thrombus. The presence of a malign thrombus due to HCC has a dismal prognosis, which affects treatment choices. We present three cases of tumor thrombi due to advanced HCC detected by ¹⁸F-FDG PET/CT.

Relationships between hypoxia induced factor-1α and 18F-FDG PET/CT parameters in colorectal cancer

AIM

The hypoxia-inducible factor 1 (HIF-1) has a critical role in oxygen homeostasis and it is a transcriptional activator of angiogenesis, erythropoiesis, iron and glucose metabolism. Glucose metabolism rate is increased in some tumours via HIF-1α. Our aim is to evaluate the relationship between hypoxia in colorectal cancer, PET parameters, necrotic tissue size and pathologic prognostic factors via using HIF-1α.

MATERIALS/METHODS

70 patients (28 female/42 male; median age: 63 years) who were diagnosed with colorectal cancer via biopsy were staged with preoperative PET/CT and operated subsequently. Immunohistochemical evaluation scoring was done according to nuclear HIF-1α expression, staining density and intensity. Metabolic tumour volume (MTV), total lesion glycolysis (TLG) and tumour volume (TV) were calculated by using volume of an ellipsoid formula via CT images, and percentage of tumour necrosis (%TmNcr) that was calculated by the difference between TV and recorded MTV.

RESULTS

There was a moderately meaningful positive correlation between tumour SUVmax and TV and %TmNcr (r=0.403, p=0.001 and r=0.500, p=0.0001, respectively). There were no statistically significant relationships between HIF-1α expression levels and tumour SUVmax, TLG, MTV, TV, %TmNcr, tumour stage, lymphovascular invasion, perineural invasion and extracapsular/capsular lymph node involvement. On the other hand, strong nuclear immunohistochemical staining was seen in tumour cells adjacent to invasive border, inflammatory cells. Although not statistically significant, moderate or strong nuclear staining were seen in 64.9% of metastatic patients.

CONCLUSION

Although the presence of a positive correlation between tumour SUVmax and %TmNcr shows that there are hypoxic cells in cancer tissue with high FDG uptake, the relationship between the presence of HIF-1α and enhanced glucose metabolism and pathological prognostic factors of tumour was not shown. Strong nuclear immunohistochemical staining in tumour cells adjacent to invasive border and inflammatory cells leads us to believe that HIF-1α plays a role in the invasion area of tumour microenvironment.

Global heterogeneity assessed with 18F-FDG PET/CT. Relation with biological variables and prognosis in locally advanced breast cancer

AIM

To analyze the relationship between measurements of global heterogeneity, obtained from ¹⁸F-FDG PET/CT, with biological variables, and their predictive and prognostic role in patients with locally advanced breast cancer (LABC).

MATERIAL AND METHODS

68 patients from a multicenter and prospective study, with LABC and a baseline ¹⁸F-FDG PET/CT were included. Immunohistochemical profile [estrogen receptors (ER) and progesterone receptors (PR), expression of the HER-2 oncogene, Ki-67 proliferation index and tumor histological grade], response to neoadjuvant chemotherapy (NC), overall survival (OS) and disease-free survival (DFS) were obtained as clinical variables. Three-dimensional segmentation of the lesions, providing SUV, volumetric [metabolic tumor volume (MTV) and total lesion glycolysis (TLG)] and global heterogeneity variables [coefficient of variation (COV) and SUVmean/SUVmax ratio], as well as sphericity was performed. The correlation between the results obtained with the immunohistochemical profile, the response to NC and survival was also analyzed.

RESULTS

Of the patients included, 62 received NC. Only 18 responded. 13 patients relapsed and 11 died during follow-up. ER negative tumors had a lower COV (p=0.018) as well as those with high Ki-67 (p=0.001) and high risk phenotype (p=0.033) compared to the rest. No PET variable showed association with the response to NC nor OS. There was an inverse relationship between sphericity with DFS (p=0.041), so, for every tenth that sphericity increases, the risk of recurrence decreases by 37%.

CONCLUSIONS

Breast tumors in our LABC dataset behaved as homogeneous and spherical lesions. Larger volumes were associated with a lower sphericity. Global heterogeneity variables and sphericity do not seem to have a predictive role in response to NC nor in OS. More spherical tumors with less variation in gray intensity between voxels showed a lower risk of recurrence.

Diagnostic impact of 18F-FDG PET/CT on the management of rare breast carcinomas: Apocrine and neuroendocrine carcinomas

OBJECTIVE

We aimed to evaluate the diagnostic impact of ¹⁸F-FDG PET/CT in staging apocrine breast carcinoma (ABC) and primary breast neuroendocrine carcinoma (PBNEC) and to demonstrate possible alterations of the ¹⁸F-FDG uptake in these histopathologic subtypes. In addition, we aimed to compare ¹⁸F-FDG PET/CT findings between ABC, PBNEC and invasive ductal carcinoma.

MATERIAL AND METHODS

A total of 570 patients and 585 breast lesions were retrospectively included in this study. After patients were classified into molecular subtypes according to the histopathological analysis, ¹⁸F-FDG PET/CT imaging was performed. The SUVmax findings of primary tumors obtained from ¹⁸F-FDG PET/CT were compared between the groups.

RESULTS

Invasive ductal carcinoma was the most prevalent breast carcinoma (77.7%, n=446), with a low proportion of ABC (4.1%, n=24) and PBNEC (2.4%; n=14) diagnosed. The highest mean SUVmax was calculated in HER2 subtype of ABC and ¹⁸F-FDG uptake ratio in HER2 and TN subtypes were found statistically higher than Luminal B type of ABC (p=0.038 and p=0.019, respectively). Although ¹⁸F-FDG uptake in Luminal B subtype of PBNEC was higher than Luminal A subtype, difference was not statistically significant. Additionally, the axillary metastasis rate was significantly higher in the ABC group (p=0.015).

CONCLUSIONS

The histopathological ABC subtype group showed different ¹⁸F-FDG uptake than the invasive ductal carcinoma group. Even if ¹⁸F-FDG uptake was lower in the PBNEC group than in the other groups, PET/CT showed and adequate performance in detecting primary tumors and metastases. The ¹⁸F-FDG PET/CT scan results may contribute to the initial staging and management of ABC and PBNEC patients.

18F-FDG PET/CT in staging and delineation of radiotherapy volume for head and neck cancer

PURPOSE

The aim is to investigate the use of ¹⁸F-FDG (fluorine-18 fluorodeoxyglucose) PET/CT in head and neck cancer (HNC) staging and its effect on the therapeutic strategy and radiotherapy (RT) planning.

METHODS AND MATERIALS

One hundred patients with HNC were included. Primary tumor sites: 18% oral cavity, 20% oropharynx, 12% hypopharynx, 11% nasopharynx, 37% larynx, 2% paranasal sinuses. Patients were staged according to the American Joint Committee of Cancer 7th edition. Stage: 5% stage I, 7% stage II, 14% stage III, 61% stage IVA, 7% stage IVB and 6% stage IVC. A contrast-enhanced CT and a ¹⁸F-FDG PET/CT acquired under RT position were performed. Both exams were compared to analyze patients' staging reclassification. Changes in therapeutic strategy were analyzed.

RESULTS

¹⁸F-FDG PET/CT detected 6 distant metastases and treatment intention changed to palliative. Eight synchronous tumors were detected; one received palliative treatment. ¹⁸F-FDG PET/CT reclassified cTNM staging in 27patients. Tumor extension changed in 28 (14% up-staged; 14% down-staged), implying a change in GTV (Gross Tumor Volume) delineation. Nodal detection was reclassified in 47 patients: 8 patients down-staged (N2C to N2A/N2B/N1) and 2 were false positive. Nineteen patients were false negatives and 5 staged as N+(N1/N2A/N2B) turned out into N2C. These staging modifications imply adapting the nodal volume to be irradiated.

CONCLUSIONS

¹⁸F-FDG PET/CT reclassification was higher than 10% in almost all categories studied (cTNM, tumor extension and nodal disease) and detects more metastases and synchronous tumors than conventional studies, which has an impact on the therapeutic patient management and RT planning.

Clinical and prognostic value of 18F-FDG PET/CT in recurrent endometrial carcinoma

PURPOSE

Endometrial carcinoma (EC) is a cancer with a good overall prognosis, except in cases of recurrent or advanced EC. The aim of this study was to assess the diagnostic performance, the prognostic value and the impact on therapeutic management of ¹⁸F-FDG PET/CT in suspected recurrent EC.

MATERIALS AND METHODS

We retrospectively evaluated 157 patients with histologically proven EC and restaging ¹⁸F-FDG PET/CT for suspected recurrence. The PET images were analyzed visually and semi-quantitatively by measuring SUVmax, MTV and TLG. A combination of clinical/imaging follow-up and/or histopathology was taken as reference standard. Progression-free survival (PFS) and overall survival (OS) were computed using Kaplan-Meier curves.

RESULTS

Seventy-nine patients had positive ¹⁸F-FDG PET/CT showing the presence of at least one hypermetabolic lesion consistent with recurrence, while the remaining 78 were negative. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ¹⁸F-FDG PET/CT were 96%, 99%, 99%, 96%, 97%, respectively, and were higher compared to conventional imaging: 97%, 62%, 72%, 96%, 80%. After a mean follow-up of 39months, relapse/progression occurred in 58 patients and death in 37 with an average time of 22.1 and 27.6months, respectively. A positive ¹⁸F-FDG PET/CT and advanced FIGO stage were significantly associated with shorter PFS and OS. PET/CT results had a significant impact on therapeutic approach in 33 patients: avoiding unnecessary therapies in 28 and modifying therapy in 5.

CONCLUSIONS

¹⁸F-FDG PET/CT has a very good diagnostic performance in patients with suspected recurrent EC and has an important prognostic value in assessing PFS and OS. Moreover, PET/CT allowed for a change in treatment decision in about 20% of cases.

Role of 18F-FDG PET/CT in restaging and follow-up of patients with uterine sarcomas

PURPOSE

Uterine sarcomas are rare tumors with poor prognosis due to the high recurrence rates. The current role of ¹⁸F-FDG PET/CT in the post-therapy surveillance is not established yet.

MATERIALS AND METHODS

Forty-one women with uterine sarcoma underwent 73 ¹⁸F-FDG PET/CT for restaging in suspected recurrence or during follow-up in asymptomatic patients. Histopathology results and/or clinical/imaging follow-up for at least 12 months were considered the reference standard. The diagnostic accuracy and clinical impact of ¹⁸F-FDG PET/CT was calculated.

RESULTS

Thirty-three ¹⁸F-FDG PET/CT were positive, while the remaining 40 studies were negative. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of ¹⁸F-FDG PET/CT were 88%, 98%, 97%, 91% and 93%, respectively. Considering patients with clinical or radiological suspicion of recurrence (n=47) and those during follow-up (n=26), sensitivity, specificity, PPV, NPV and accuracy of ¹⁸F-FDG PET/CT were 89%, 100%, 100%, 86% and 94%, and 80%, 95%, 80%, 95% and 92%, respectively. ¹⁸F-FDG PET/CT had a positive clinical impact in 9/73 (12%) studies and changed the clinical management in 8/41 (20%) patients.

CONCLUSIONS

¹⁸F-FDG PET/CT seems to be an accurate method for detection and localization of local and distant recurrence in patients with uterine sarcoma with good sensitivity and specificity and significant impact on clinical decision making.

Prognostic value of primary tumor SUVmax on pre-treatment 18F-FDG PET/CT imaging in patients with stage iii non-small cell lung cancer

OBJECTIVES

Concomitant chemoradiotherapy (CCRT) is widely used in the treatment of patients with stage iii non-small cell lung carcinoma (NSCLC). The early identification of patients with poor prognosis is the premise of personalized treatment for patients. The aim of the study was to evaluate the prognostic value of clinical parameters and primary tumor SUVmax on pre-treatment 18F-FDG PET/CT in patients with stage iii NSCLC.

MATERIAL AND METHODS

Clinical records of 79 stage iii-NSCLC patients with pre-treatment 18F-FDG PET/CT imaging, treated with definitive CCRT were retrospectively reviewed. The clinical endpoints in terms of progression-free survival (PFS) and overall survival (OS) were correlated with the median pre-treatment primary tumor SUVmax. Furthermore, other factors influencing patient outcome were analyzed.

RESULTS

The median age of patients was 58 years (range, 45-71) with 72 (91%) males. Squamous cell carcinoma (73%) was the most common histologic type. Performance status was very good (ECOG 0) in 64.5% of patients. Sixty (79%) patients had died at the time of this analysis. Median OS and PFS were 22.5 and 12.0 months, respectively. Patients were dichotomized according to pre-treatment primary tumor SUVmax≤15.0 vs.>15.0. There was no statistically significant difference for OS and PFS in both arms. Multivariate analysis showed that pre-treatment SUVmax was not a significant predictor of OS (HR 1.099, P=0.726) and PFS (HR 1.022, P=0.941).

CONCLUSIONS

SUVmax with threshold value of 15.0 on the primary tumor before treatment had no prognostic value in our patient group with stage iii NSCLC treated with definitive CCRT.

Predictive and prognostic potential of volume-based metabolic variables obtained by a baseline 18F-FDG PET/CT in breast cancer with neoadjuvant chemotherapy indication

AIM

To investigate the usefulness of metabolic variables using ¹⁸F-FDG PET/CT in the prediction of neoadjuvant chemotherapy (NC) response and the prognosis in locally advanced breast cancer (LABC).

MATERIAL AND METHODS

Prospective study including 67 patients with LABC, NC indication and a baseline ¹⁸F-FDG PET/CT. After breast tumor segmentation, SUV variables (SUVmax, SUVmean and SUVpeak) and volume-based variables, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), were obtained. Tumors were grouped into molecular phenotypes, and classified as responders or non-responders after completion of NC. Disease-free status (DFs), disease-free survival (DFS), and overall survival (OS) were assessed. A univariate and multivariate analysis was performed to study the potential of all variables to predict DFs, DFS, and OS.

RESULTS

Fourteen patients were classified as responders. Median±SD of DFS and OS was 43±15 and 46±13 months, respectively. SUV and TLG showed a significant correlation (p<0.005) with the histological response, with higher values in responders compared to non-responders. MTV and TLG showed a significant association with DFs (p=0.015 and p=0.038 respectively). Median, mean and SD of MTV and TLG for patients with DFs were: 8.90, 13.73, 15.10 and 33.78, and 90.54 and 144.64, respectively. Median, mean and SD of MTV and TLG for patients with non-DFs were: 16.72, 29.70 and 31.09 and 90.89, 210.98 and 382.80, respectively. No significant relationships were observed with SUV variables and DFs. Volume-based variables were significantly associated with OS and DFS, although in multivariate analysis only MTV was related to OS. No SUV variables showed an association with the prognosis.

CONCLUSION

Volume-based metabolic variables obtained with ¹⁸F-FDG PET/CT, unlike SUV based variables, were good predictors of both neoadjuvant chemotherapy response and prognosis.

Correlation of 18F-FDG uptake on PET/CT with Ki67 immunohistochemistry in pre-treatment epithelial ovarian cancer

OBJECTIVE

Standardised uptake value (SUV) and volumetric parameters such as metabolic tumour volume (MTV) and total lesion glycolysis (TLG) from ¹⁸F-FDG PET/CT are useful criteria for disease prognosis in pre-operative and post-treatment epithelial ovarian cancer (EOC). Ki67 is another prognostic biomarker in EOC, associated with tumour aggressiveness. The aim of this study is to evaluate the association between ¹⁸F-FDG PET/CT measurements and Ki67 in pre-treatment EOC to determine if PET/CT parameters could non-invasively predict tumour aggressiveness.

MATERIAL AND METHODS

A pre-treatment PET/CT was performed on 18 patients with suspected or newly diagnosed EOC. Maximum SUV (SUVmax), mean SUV (SUVmean), whole-body MTV (wbMTV), and whole-body TLG (wbTLG) with a threshold of 30% and 40% of the SUVmax were obtained. Furthermore, Ki67 index (mean and hotspot) was estimated in tumour tissue specimens. Immunohistochemical findings were correlated with PET parameters.

RESULTS

The mean age was 57.0 years old (standard deviation 13.6 years). A moderate correlation was observed between mean Ki67 index and SUVmax (r=0.392), SUVmean 30% (r=0.437), and SUVmean 40% (r=0.443), and also between hotspot Ki67 index and SUVmax (r=0.360), SUVmean 30% (r=0.362) and SUVmean 40% (r=0.319). There was a weaker correlation, which was inversely negative, between mean and hotspot Ki67 and volumetric PET parameters. However, no statistical significant differences were found for any correlations.

CONCLUSIONS

SUVmax and SUVmean were moderately correlated with Ki67 index, whereas volumetric PET parameters overall, showed a weaker correlation. Thus, SUVmax and SUVmean could be used to assess tumour aggressiveness in pre-treatment EOC.

Can metabolic tumor parameters on primary staging 18F-FDG PET/CT aid in risk stratification of primary central nervous system lymphomas for patient management as a prognostic model?

OBJECTIVE

Primary central nervous system (CNS) lymphoma is an aggressive and fatal extranodal non-Hodgkin lymphoma jailed in CNS at initial diagnosis. Its prognosis is poor and the disease has a fatal outcome when compared with systemic non-Hodgkin lymphoma. A few baseline risk stratification scoring systems have been suggested to estimate the prognosis mainly based on serum lactate dehydrogenase level,age, Karnofsky performance score, involvement of deep brain structures and cerebrospinal fluid protein concentration. ¹⁸F-FDG PET/CT has a high prognostic value with respect to overall survival and disease-free survival in many cancers and lymphomas. We aimed to investigate metabolic tumor indexes on primary staging ¹⁸F-FDG PET/CT as prognostic markers in primary CNS lymphoma.

MATERIAL AND METHODS

Fourteen patients with primary CNS diffuse large B-cell lymphoma (stage i) were enrolled in this retrospective cohort study. Primary staging ¹⁸F-FDG PET/CT was performed and quantitative parameters like maximum standardized uptake value, average standardized uptake value, metabolic tumor volume and total lesion glycolysis (TLG) were calculated for all patients before the treatment. Cox regression models were performed to determine their relation with survival time.

RESULTS

In the evaluation of all potential risk factors impacting recurrence/metastases (age, sex, serum lactate dehydrogenase, involvement of deep brain structures, maximum standardized uptake value, average standardized uptake value, metabolic tumor volume, and TLG) with univariate analysis, TLG remained statistically significant (P=.02).

CONCLUSION

Metabolic tumor parameters are useful in prognosis estimation of primary CNS lymphomas, especially TLG, which is the most important one and may play a role in patient management.

Primary squamous cell carcinoma of the thyroid. Initial assessment and follow-up using 18F-FDG PET/CT

Squamous cell carcinoma of thyroid is an uncommon, very aggressive neoplasm, having a poor prognosis and poor response to chemotherapy and radiotherapy. Surgery is the initial treatment of choice, although it often presents as a widespread disease at the time of diagnosis, usually with cervical swelling that causes most of the symptoms due to local infiltration or metastasis. Local infiltration from adjacent tumour and metastatic disease needs to be excluded from other primary epidermoid carcinomas, in order to make a correct diagnosis. This also requires the typical cytokeratin pattern seen in histological studies. The case is presented of a 53 year-old man with a medical history of hepatocarcinoma, with a cervical hypermetabolic lesion detected in an ¹⁸F-FDG PET/CT performed to exclude widespread disease. The follow-up of this lesion with this technique and its usefulness is also described.

PET/CT in giant cell arteritis: High 18F-FDG uptake in the temporal, occipital and vertebral arteries

¹⁸F-FDG PET/CT imaging is useful in patients with fever of unknown origin and can detect giant cell arteritis in extracranial large arteries. However, it is usually assumed that temporal arteries cannot be visualized with a PET/CT scanner due to their small diameter. Three patients with clinical symptoms of temporal arteritis were examined using a standard whole body PET/CT protocol (skull base - mid thighs) followed by a head PET/CT scan using the brain protocol. High ¹⁸F-FDG uptake in the aorta and some arterial branches were detected in all 3 patients with the whole body protocol. Using the brain protocol, head imaging led to detection of high ¹⁸F-FDG uptake in temporal arteries as well as in their branches (3 patients), in occipital arteries (2 patients) and also in vertebral arteries (3 patients).

Febrile syndrome of unknown origin: Indications for 18F-FDG PET/CT in inflammatory and infectious processes

Fever of unknown origin is defined as a body temperature greater than 38.3°C lasting more than three weeks for which the cause could not be found within one week of hospital admission. More than 200 causes have been reported, and these can be classified into four categories: infections, inflammatory diseases, oncologic processes, and miscellaneous conditions. Noninvasive diagnostic techniques are used in 69.2% of cases and invasive techniques in 30.8%. Structural imaging techniques show the morphological changes from infectious, inflammatory, and tumor-related processes, but they do not allow the detection of the early changes brought about by these processes. The metabolic information provided by ¹⁸F-FDG PET/CT has a promising role in these patients. ¹⁸F-FDG uptake is based on the cells' use of glucose as a source of energy, so it can be observed in infectious, inflammatory, and tumor-related processes. The established non-oncologic indications for ¹⁸F-FDG PET/CT are sarcoidosis, osteomyelitis, spondylodiscitis, fever of unknown origin, and vasculitis, which together account for more than 85% of studies.

Basal (18)F-FDG PET/CT in follicular lymphoma: A comparison of metabolic and clinical variables in the prognostic assessment

AIM

To analyze the relationship of clinical variables related to prognosis and tumor burden, with metabolic variables obtained in the staging (18)F-FDG PET/CT, and their value in the prognosis in follicular lymphoma (FL).

METHODS

82 patients with FL, a (18)F-FDG PET/CT at diagnosis and a follow-up for a minimum of 12 months, were retrospectively enrolled in the present study. Clinical variables (Tumor grade, Follicular Lymphoma International Prognostic Index (FLIPI) and Tumor burden) were evaluated. Metabolic variables such as SUVmax in the highest hypermetabolic lesion, extralymphatic locations, number of involved lymph node locations, bone marrow (BM) involvement, PET stage and diameter of the biggest hypermetabolic lesion, were analyzed in order to establish a PET score and classify the studies in low, intermediate and high metabolic risk. Clinical and metabolic variables (included metabolic risk) were compared. The relation among all variables and disease-free survival (DFS) was studied.

RESULTS

The 28% of patients had a high-grade tumor. The 30.5% had FLIPI risk low, 29.3% intermediate y 40.2% high. The 42.7% presented a high tumor burden. The PET/CT was positive in 94% of patients. The tumor grade did not show significant relation with metabolic variable. FLIPI risk and tumor burden showed statistical relations with the SUV max and the PET score (p<0.008 and p=0.003 respectively). With respect to DFS, significant differences were detected for the PET stage and FLIPI risk (p=0.015 and p=0.047 respectively). FLIPI risk was the only significant predictor in Cox regression analysis, with a Hazard Ratio of 5.13 between high risk and low risk.

CONCLUSION

The present research highlights the significant relation between metabolic variables obtained with FDG PET/CT and clinical variables although their goal as an independent factor of prognosis was not demonstrated in the present work.

18F-FDG positron emission tomography in oncology: main indications

The development of molecular and functional imaging with new imaging techniques such as computed tomography, magnetic resonance imaging, and positron emission tomography (PET) among others, has greatly improved the detection of tumors, tumor staging, and the detection of possible recurrences. Furthermore, the combination of these different imaging modalities and the continual development of radiotracers for PET have advanced our understanding and knowledge of the different pathophysiological processes in cancer, thereby helping to make treatment more efficacious, improving patients' quality of life, and increasing survival. PET is one of the imaging techniques that has attracted the most interest in recent years for its diagnostic capabilities. Its ability to anatomically locate pathologic foci of metabolic activity has revolutionized the detection and staging of many tumors, exponentially broadening its potential indications not only in oncology but also in other fields such as cardiology, neurology, and inflammatory and infectious diseases.

Report of a case

Radical cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy increases survival in patients with end-stage peritoneal carcinomatosis, and who are under palliative therapy. The Peritoneal Cancer Index enables the tumor burden to be quantified during surgery, as well as treatment planning and patient prognosis. It is obtained by combining the tumor spread in 13 abdominal and pelvic regions with the largest tumor size. Fluorodeoxyglucose positron emission tomography/computed tomography is the technique of choice for those patients selected to undergo radical cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy, due to its higher detection rate of carcinomatosis, and since it allows extra-peritoneal disease staging. The simplified Peritoneal Cancer Index (9 regions defined by 2 transverse and 2 sagittal planes) obtained by fluorodeoxyglucose positron emission tomography/computed tomography allows correlation with the surgical procedure, therefore its standardization is advisable.

Paraneoplastic pemphigus as a first sign of metastatic retroperitoneal inflammatory myofibroblastic tumor: (18)F-FDG PET/CT findings

A 30-year-old female presented with a 3-month history of erosive stomatitis and bullous lesions, along with recurrent episodes of abdominal pain. She was found to have a retroperitoneal lump in left lumbar region. Skin biopsy revealed bullous disorder. CT guided biopsy of the retroperitoneal mass was suggestive of inflammatory myofibroblastic tumor (IMT). She was started on oral steroids and supportive care, and surgery was being planned when she developed respiratory failure. CT chest revealed vertebral metastases. PET/CT for whole body work up revealed a left para-aortic mass along with multiple skeletal metastases. The patient was kept on conservative management. After 3 months, the patient has shown clinical improvement, and an exploratory laparotomy is now being planned for the excision of the tumor, followed by chemotherapy. This case of retroperitoneal IMT is rare in terms of skeletal metastases with paraneoplastic pemphigus.

The utility of 18F-FDG PET/CT in solitary fibrous tumors of the pleura

OBJECTIVE

To demonstrate the utility of (18)F-FDG PET/CT in the differentiation of benign and malignant solitary fibrous tumors of the pleura (SFTP).

MATERIALS AND METHODS

A retrospective review was performed on the (18)F-FDG PET/CT data from 17 patients with histopathologically diagnosed benign or malignant SFTP. The size, side of SFTP, presence of necrosis, calcification, pleural effusion, hilar lymphadenopathy (LAP), density on CT images (Hounsfield unit-HU), and (18)F-FDG uptake (SUVmax) were recorded and compared in order to detect malignant SFTP. Statistical significance was set as p<0.05.

RESULTS

The difference in size, presence of necrosis, and hilar LAP on CT images were statistically significant (p=0.004, p<0.001, p=0.015, respectively) in a comparison of benign and malignant SFTPs. The mean HU of benign SFTP was 46.16±5.52HU, and for malignant SFTP it was 35.03±4.61HU (p=0.003). The mean SUVmax was 3.02±1.02 for benign SFTP and 4.89±2.12 for malignant SFTP (p=0.021). A cut-off value of ≥7cm for size, ≤39.81HU for density, and ≥3.47 for SUVmax was obtained by ROC analysis for detecting malignant SFTP.

CONCLUSIONS

(18)F-FDG PET/CT may have a limited role in diagnosing malignant SFTP in suspected patients.

Basal (18)F-FDG PET/CT as a predictive biomarker of tumor response for neoadjuvant therapy in breast cancer

PURPOSE

To explore the relation between tumor kinetic assessed by (18)F-FDG PET and final neoadjuvant chemotherapy (NC) response within a molecular phenotype perspective.

MATERIAL AND METHODS

Prospective study included 144 women with breast cancer. All patients underwent a dual-time point (18)F-FDG PET/CT previous to NC. The retention index (RI), between SUV-1 and SUV-2 was calculated. Molecular subtypes were re-grouped in low, intermediate and high-risk biological phenotypes. After NC, all residual primary tumor specimens were histopathologically classified in tumor regression grades (TRG) and response groups. The relation between SUV-1, SUV-2 and RI with the TRG and response groups was evaluated in all molecular subtypes and in accordance with the risk categories.

RESULTS

Responder's lesions showed significant greater SUVmax compared to non-responders. The RI value did not show any significant relation with response. Attending to molecular phenotypes, statistical differences were observed with greater SUV for responders having high-risk molecular subtypes.

CONCLUSION

Glycolytic tumor characteristics showed a significant correlation with NC response and dependence of risk phenotype.

Glycolytic activity in breast cancer using 18F-FDG PET/CT as prognostic predictor: A molecular phenotype approach

AIM

To explore the relationship between basal (18)F-FDG uptake in breast tumors and survival in patients with breast cancer (BC) using a molecular phenotype approach.

MATERIAL AND METHODS

This prospective and multicentre study included 193 women diagnosed with BC. All patients underwent an (18)F-FDG PET/CT prior to treatment. Maximum standardized uptake value (SUVmax) in tumor (T), lymph nodes (N), and the N/T index was obtained in all the cases. Metabolic stage was established. As regards biological prognostic parameters, tumors were classified into molecular sub-types and risk categories. Overall survival (OS) and disease free survival (DFS) were obtained. An analysis was performed on the relationship between semi-quantitative metabolic parameters with molecular phenotypes and risk categories. The effect of molecular sub-type and risk categories in prognosis was analyzed using Kaplan-Meier and univariate and multivariate tests.

RESULTS

Statistical differences were found in both SUVT and SUVN, according to the molecular sub-types and risk classifications, with higher semi-quantitative values in more biologically aggressive tumors. No statistical differences were observed with respect to the N/T index. Kaplan-Meier analysis revealed that risk categories were significantly related to DFS and OS. In the multivariate analysis, metabolic stage and risk phenotype showed a significant association with DFS.

CONCLUSION

High-risk phenotype category showed a worst prognosis with respect to the other categories with higher SUVmax in primary tumor and lymph nodes.

Prognostic value of (18)F-FDG PET/CT volumetric parameters in recurrent epithelial ovarian cancer

OBJECTIVE

Metabolic tumour volume (MTV) and total lesion glycolysis (TLG) from (18)F-FDG PET/CT are emerging prognostic biomarkers in various solid neoplasms. These volumetric parameters and the SUVmax have shown to be useful criteria for disease prognostication in preoperative and post-treatment epithelial ovarian cancer (EOC) patients. The purpose of this study was to evaluate the utility of (18)F-FDG PET/CT measurements to predict survival in patients with recurrent EOC.

MATERIAL AND METHODS

Twenty-six patients with EOC who underwent a total of 31 (18)F-FDG PET/CT studies for suspected recurrence were retrospectively included. SUVmax and volumetric parameters whole-body MTV (wbMTV) and whole-body TLG (wbTLG) with a threshold of 40% and 50% of the SUVmax were obtained. Correlation between PET parameters and progression-free survival (PFS) and the survival analysis of prognostic factors were calculated.

RESULTS

Serous cancer was the most common histological subtype (76.9%). The median PFS was 12.5 months (range 10.7-20.6 months). Volumetric parameters showed moderate inverse correlation with PFS but there was no significant correlation in the case of SUVmax. The correlation was stronger for first recurrences. By Kaplan-Meier analysis and log-rank test, wbMTV 40%, wbMTV 50% and wbTLG 50% correlated with PFS. However, SUVmax and wbTLG 40% were not statistically significant predictors for PFS.

CONCLUSION

Volumetric parameters wbMTV and wbTLG 50% measured by (18)F-FDG PET/CT appear to be useful prognostic predictors of outcome and may provide valuable information to individualize treatment strategies in patients with recurrent EOC.

Bilateral symmetrical adrenal hypermetabolism on FDG PET/CT due to Cushing syndrome in well differentiated neuroendocrine carcinoma

The (18)F-FDG PET/CT scan has been suggested for whole-body imaging to identify ectopic adrenocorticotrophic hormone secreting tumours, but there are some challenges involved. The case of a patient is presented, who was admitted with the pre-diagnosis of ectopic ACTH syndrome. On the CT, a nodular lesion was detected in the medial segment of the right lung. The FDG uptake of the lesion seemed to be increased visually, but was not pathological quantitatively (SUVmax: 1.8) on the PET/CT. There was also diffuse increased uptake (SUVmax: 14.2) in the enlarged adrenal glands. The lesion was reported as a possible malignant lesion with low FDG affinity, such as a low grade neuroendocrine tumour, while the diffuse enlarged adrenal glands with high uptake were interpreted as diffusely hyperplasic, due to Cushing's syndrome. The patient was treated with a surgical wedge resection. The histopathological diagnosis confirmed that the tumour was a grade 1 well-differentiated neuroendocrine carcinoma.

The contribution of ¹⁸F-FDG PET/CT in a patient with cutaneous metastases of squamous cell carcinoma of the penis

A 61-year-old patient was diagnosed with squamous cell carcinoma of the penis (SCCP) and treated with partial penectomy (pT1,N0,M0,G2). Seven months later, a palpable adenopathy was found in the left inguinal region. An (18)F-FDG PET/CT exploration showed hypermetabolic lymphadenopathies in inguinal, pelvic, retroperitoneal regions, in both lung hila and in the left supraclavicular regions. At the end of the 4th cycle of chemotherapy (cisplatin+5FU) the patient developed numerous skin metastases at the root of the left thigh and a pleural effusion in the right lung. In a new exploration with (18)F-FDG PET/CT the number, size and metabolic activity of known lymphadenopathies decreased. Right pleural carcinomatosis and intense FDG uptake in cutaneous metastases were observed. Weeks later, the patient died. (18)F-FDG-PET/TC may be useful in patients with SCCP and metastatic inguinal lymphadenopathies, to assess the response to chemotherapy and to detect other unsuspected metastases in the rare cases of cutaneous metastases.

Unusual ¹⁸F-FDG PET/CT finding of an oxyphil parathyroid adenoma in a patient with Hodgkin's Lymphoma

Malignancy-associated hypercalcemia is a complication of advanced tumours that is associated to a poor prognosis. Thorough evaluation to establish its cause is essential because some patients may actually have undiagnosed primary hyperparathyroidism. We report a case of a patient affected by Hodgkin's Lymphoma and persistent hypercalcemia with an incidental (18)F-FDG PET/CT finding in the anterior neck region, not ascribable to malignancy, confirmed with (99m)Tc-sestamibi scintigraphy. It was removed by minimally invasive surgery. It was shown to be an oxyphil parathyroid adenoma localized in an unusual site.

(18)F-FDG PET/CT findings in a case with HIV (-) Kaposi sarcoma

Although mucocutaneous sites are the most frequently encountered sites of involvement, Kaposi Sarcoma (KS) may also occasionally involve the breast and the skeletal, endocrine, urinary and nervous systems.. Various imaging modalities may be used to delineate the extent of the disease by detecting unexpected sites of involvement. Herein, we report a case of classical type KS, in whom staging with (18)F-FDG PET/CT imaging disclosed widespread disease and unexpected findings of bone and salivary gland involvement.

[Update on the use of PET radiopharmaceuticals in inflammatory disease]

The use of molecular imaging with PET/CT technology using different radiotracers, especially the (18)F-FDG is currently spreading beyond the area of oncology, the most interest being placed on inflammatory and infectious diseases. This article presents a review of its contribution in different inflammatory conditions in the context of structural and conventional nuclear medicine imaging. Special emphasis is placed on the more significant diseases such as large-vessel vasculitis, sarcoidosis, rheumatoid arthritis and inflammatory bowel disease and the study of the atheroma plaque.

Extensive hypermetabolic pattern of brown adipose tissue activation on 18F-FDG PET/CT in a patient diagnosed of catecholamine-secreting para-vesical paraganglioma

The widespread use of (18)F-FDG PET-CT scanning in oncological patients has allowed to demonstrate the existence of metabolically active brown fat, also called brown adipose tissue (BAT), in adult humans, and specifying its anatomical distribution in vivo. As physiological determinants to BAT (18)F-FDG uptake has been identified gender, age, temperature, and body mass index. We have observed extensive activation of the BAT, including the mesenteric region, in a patient with a catecholamine-secreting para-vesical paranganglioma. The extensive BAT activation could be secondary to adrenergic stimulation due to excess of circulating norepinephrine concentration.