Different predictive values of interim <Superscript>18</Superscript>F-FDG PET/CT in germinal center like and non-germinal center like diffuse large B-cell lymphoma

Purpose

Diffuse large B-cell lymphoma (DLBCL) is a pathologically heterogeneous disease with different prognoses according to its molecular profiles. Despite the broad usage of ¹⁸F-fluoro-2-dexoxy-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT), previous studies that have investigated the value of interim ¹⁸F-FDG PET/CT in DLBCL have given the controversial results. The purpose of this study was to evaluate the prognostic value of interim ¹⁸F-FDG PET/CT in DLBCL according to germinal center B cell-like (GCB) and non-GCB molecular profiling.

Methods

We enrolled 118 newly diagnosed DLBCL patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP). Interim ¹⁸F-FDG PET/CT scans performed after 2 or 3 cycles of R-CHOP treatment were evaluated based on the Lugano response criteria. Patients were grouped as GCB or non-GCB molecular subtypes according to immunohistochemistry results of CD10, BCL6, and MUM1, based on Hans’ algorithm.

Results

In total 118 DLBCL patients, 35 % were classified as GCB, and 65 % were classified as non-GCB. Interim PET/CT was negative in 70 %, and positive in 30 %. During the median follow-up period of 23 months, the positive interim ¹⁸F-FDG PET/CT group showed significantly inferior progression free survival (PFS) compared to the negative interim ¹⁸F-FDG PET/CT group (P = 0.0004) in entire patients. A subgroup analysis according to molecular profiling demonstrated significant difference of PFS between the positive and negative interim ¹⁸F-FDG PET groups in GCB subtype of DLBCL (P = 0.0001), but there was no significant difference of PFS between the positive and negative interim ¹⁸F-FDG PET groups in non-GCB subtype of DLBCL.

Conclusions

Interim ¹⁸F-FDG PET/CT scanning had a significant predictive value for disease progression in patients with the GCB subtype of DLBCL treated with R-CHOP, but not in those with the non-GCB subtype. Therefore, molecular profiles of DLBCL should be considered for interim ¹⁸F-FDG PET/CT practice.

     

Diagnostic value of full-dose FDG PET/CT for axillary lymph node staging in breast cancer patients

Purpose

The aims of this study were (1) to evaluate FDG PET/CT and CT for the detection of axillary lymph node metastases in breast cancer (BC) patients and (2) to evaluate FDG PET/CT as a pre-test for the triage to sentinel lymph node biopsy (SLNB) versus axillary lymph node dissection (ALND).

Methods

The sensitivity, specificity, positive and negative predictive value (PPV, NPV), and accuracy of FDG PET/CT and CT for axillary lymph node metastases were determined in 61 patients (gold standard: histopathology). According to the equation “NPV = specificity ? (1-prevalence) / [specificity ? (1-prevalence) + (1-sensitivity) ? prevalence]” FDG PET/CT was evaluated as a triage tool for SLNB versus ALND.

Results

The sensitivity, specificity, PPV, NPV and accuracy of FDG PET/CT was 58, 92, 82, 77 and 79% and of CT 46, 89, 72, 71 and 72%, respectively. Patients with an up to ~60% risk for axillary lymph node metastases appear to be candidates for SLNB provided that the axilla is unremarkable on FDG PET/CT.

Conclusion

FDG PET/CT cannot replace invasive approaches for axillary staging but may extend the indication for SLNB.     

Interim FDG PET/CT as a prognostic factor in diffuse large B-cell lymphoma

Purpose

Interim ¹⁸F-FDG PET performed early during the course of therapy in diffuse large B-cell lymphoma (DLBCL) is a good predictor of outcome. However, interpretation criteria for interim PET for the evaluation of tumour response are still not clearly defined. The study aim was to assess whether interim PET can predict overall survival (OS) and progression-free survival (PFS) in DLBCL patients following three different sets of parameters, two qualitative (visual) methods and one semiquantitative.

Methods

A total of 50 newly diagnosed DLBCL patients were prospectively enrolled in this study. All patients had a PET/CT scan at diagnosis and an interim PET/CT scan after the second or third cycle of chemotherapy. Three methods of evaluation for the interim PET/CT were used: a qualitative three-point scoring (3-PS) method, a qualitative 5-PS method and a semiquantitative method (ΔSUV_max). The degree of correlation between therapy response seen on FDG PET and PFS and OS was determined.

Results

The analysis of the visual 3-PS method showed no statistically significant difference in PFS and OS. The estimated 5-year PFS and OS were 79 % and 92 %, respectively, in patients with an interim PET scan showing uptake not greater than in the liver versus 50 % in patients with uptake greater than in the liver, and this difference was statistically significant. The optimal cut-off value of ΔSUV_max that could predict the PFS and OS difference in patients with DLBCL was 76 % (95 % CI 62.7–89.2 %) and 75 % (95 % CI, 54.6–95.4 %), respectively.

Conclusion

Our results support the use of liver uptake as an indicator in the qualitative evaluation of interim PET, or a ΔSUV_max greater than 75 % in semiquantitative analysis. Interim PET may predict PFS and OS and could be considered in the prognostic evaluation of DLBCL.     

Poor predictive value of positive interim FDG-PET/CT in primary mediastinal large B-cell lymphoma

Purpose

Though commonly used to assess response to therapy, the prognostic value of interim FDG-PET/CT in Primary Mediastinal Large B-cell Lymphoma (PMBCL) is unclear.

Methods

We conducted a retrospective study on 36 consecutive patients treated at our institution for a PMBCL between 2006 and 2014. All patients with a positive interim FDG-PET/CT had undergone histological restaging consisting either in a surgical debulking of the residual lesion (15 patients) or a CT-guided core needle biopsy (two patients). All FDG-PET/CT were secondarily reviewed according to the more recent Deauville criteria.

Results

Interim FDG-PET/CT was considered positive in 17/36 patients using visual evaluation. Among these patients, 14 had a Deauville score of 4. Histological restaging was negative in all but one case, showing inflammation and/or fibrosis. After a median follow-up of 48.5 months, a total of five patients have relapsed, two patients in the positive FDG-PET/CT group, and three patients in the negative FDG-PET/CT group, respectively.

Conclusions

These data indicate that a positive interim FDG-PET/CT does not reflect persistence of active disease in the vast majority of PMBCL cases. The relapse rate appears similar regardless of interim FDG-PET/CT results and interpretation criteria. This suggests that interim FDG-PET/CT has a poor positive predictive value, thus kt should be used with caution in PMBCL.

     

The role of 18F-fluoride PET-CT in the detection of bone metastases in patients with breast, lung and prostate carcinoma: a comparison with FDG PET/CT and 99mTc-MDP bone scan

Objectives

We aimed to compare the role of ¹⁸F-fluoride PET/CT, FDG PET/CT and ^99mTc-MDP bone scans in the detection of bone metastases in patients with lung, breast and prostate carcinoma.

Methods

This was a prospective study including patients for staging (S) and restaging (R). Seventy-two patients (23S, 49R) with infiltrating ductal breast carcinoma, 49 patients (25S, 24R) with prostate adenocarcinoma and 30 patients (17S, 13R) with non-small-cell lung carcinoma (NSCLC), without known bone metastases but with high risk/clinical suspicion for the same, underwent a ^99mTc-MDP bone scan, FDG PET/CT and ¹⁸F-fluoride PET/CT within 2 weeks. All scans were reviewed by two experienced nuclear medicine physicians, and the findings were correlated with MRI/thin-slice CT/skeletal survey. Histological verification was done wherever feasible.

Results

Sensitivity and negative predictive value (NPV) of ¹⁸F-fluoride PET/CT was 100 % in all three malignancies, while that of FDG PET/CT was 79 % and 73 % in NSCLC, 73 % and 80 % in breast cancer and 72 and 65 % in prostate cancer. Specificity and positive predictive value (PPV) of FDG PET/CT were 100 % in NSCLC and prostate and 97 % and 96 % in breast cancer. As compared to the ^99mTc-MDP bone scan, all parameters were superior for ¹⁸F-fluoride PET/CT in prostate and breast cancer, but sensitivity and NPV were equal in NSCLC. The MDP bone scan had superior sensitivity and NPV compared to FDG PET/CT but had low specificity and PPV.

Conclusion

To rule out bone metastases in cases where there is a high index of suspicion, ¹⁸F-fluoride PET/CT is the most reliable investigation. ¹⁸F-fluoride PET/CT has the potential to replace the ^99mTc-MDP bone scan for the detection of bone metastases.     

Use of FDG PET/CT for investigation of febrile neutropenia: evaluation in high-risk cancer patients

Purpose

Febrile neutropenia (FNP) is a frequent complication of cancer care and evaluation often fails to identify a cause. [¹⁸?F]FDG PET/CT has the potential to identify inflammatory and infectious foci, but its potential role as an investigation for persistent FNP has not previously been explored. The aim of this study was to prospectively evaluate the clinical utility of FDG PET/CT in patients with cancer and severe neutropenia and five or more days of persistent fever despite antibiotic therapy.

Methods

Adult patients with a diagnosis of an underlying malignancy and persistent FNP (temperature ≥38°C and neutrophil count <500 cells/μl for 5?days) underwent FDG PET/CT as an adjunct to conventional evaluation and management.

Results

The study group comprised 20 patients with FNP who fulfilled the eligibility criteria and underwent FDG PET/CT in addition to conventional evaluation. The median neutrophil count on the day of the FDG PET/CT scan was 30 cells/μl (range 0–730 cells/μl). Conventional evaluation identified 14 distinct sites of infection, 13 (93?%) of which were also identified by FDG PET/CT, including all deep tissue infections. FDG PET/CT identified 9 additional likely infection sites, 8 of which were subsequently confirmed as “true positives” by further investigations. FDG PET/CT was deemed to be of ‘high’ clinical impact in 15 of the 20 patients (75?%).

Conclusion

This study supports the utility of FDG PET/CT scanning in severely neutropenic patients with five or more days of fever. Further evaluation of the contribution of FDG PET/CT in the management of FNP across a range of underlying malignancies is required.     

18F-FDG PET/CT bone/bone marrow findings in Hodgkin’s lymphoma may circumvent the use of bone marrow trephine biopsy at diagnosis staging

Purpose

Accurate staging of Hodgkin’s lymphoma (HL) is necessary in selecting appropriate treatment. Bone marrow trephine biopsy (BMB) is the standard procedure for depicting bone marrow involvement. BMB is invasive and explores a limited part of the bone marrow. ¹⁸F-FDG PET/CT is now widely used for assessing response to therapy in HL and a baseline study is obtained to improve accuracy. The aim of this retrospective analysis was to assess whether routine BMB remains necessary with concomitant ¹⁸F-FDG PET/CT.

Methods

Data from 83 patients (newly diagnosed HL) were reviewed. All patients had received contrast-enhanced CT, BMB and ¹⁸F-FDG PET/CT. Results of BMB were not available at the time of ¹⁸F-FDG PET/CT imaging.

Results

Seven patients had lymphomatous involvement on BMB. Four patients had bone involvement on conventional CT (two with negative BMB). All patients with bone marrow and/or bone lesions at conventional staging were also diagnosed on ¹⁸F-FDG PET/CT scan. PET/CT depicted FDG-avid bone/bone marrow foci in nine additional patients. Four of them had only one or two foci, while the other had multiple foci. However, the iliac crest, site of the BMB, was not involved on ¹⁸F-FDG PET/CT. Osteolytic/sclerotic lesions matching FDG-avid foci were visible on the CT part of PET/CT in three patients. MRI ordered in three other patients suggested bone marrow involvement. Interim and/or end-therapy ¹⁸F-FDG PET/CT documented response of FDG-avid bone/bone marrow foci to chemotherapy in every patient.

Conclusion

¹⁸F-FDG PET/CT highly improves sensitivity for diagnosis of bone/bone marrow lesions in HL compared to conventional staging.     

PET/CT for staging and follow-up of pediatric nasopharyngeal carcinoma

Purpose

While FDG PET/CT for the evaluation of nasopharyngeal carcinoma (NPC) in adult patients has documented advantages and disadvantages compared with conventional imaging, to our knowledge, no studies of FDG PET/CT for the evaluation of NPC in pediatric patients have been performed. In this investigation, we studied the utility of FDG PET/CT in children with NPC.

Methods

The study group comprised 18 children with biopsy-proven NPC who underwent FDG PET/CT and MRI (total 38 pairs of images). All baseline and follow-up FDG PET/CT and MRI studies were independently reviewed for restaging of disease.

Results

The concordance between FDG PET/CT and MRI in T, N, and overall staging was 29%, 64%, and 43%, respectively. Compared with MRI, FDG PET/CT yielded lower T and overall staging and showed less cervical and retropharyngeal lymphadenopathy. The concordance between follow-up FDG PET/CT and MRI was 79% overall and 100% 9?months after therapy. In patients who achieved complete remission, FDG PET/CT showed disease clearance 3–6?months earlier than MRI. There were no false-positive or false-negative FDG PET/CT scans during follow-up.

Conclusion

FDG PET/CT may underestimate tumor extent and regional lymphadenopathy compared with MRI at the time of diagnosis, but it helps to detect metastases and clarify ambiguous findings. FDG PET/CT is sensitive and specific for follow-up and enables earlier determination of disease remission. FDG PET/CT is a valuable imaging modality for the evaluation and monitoring of NPC in pediatric patients.     

An international confirmatory study of the prognostic value of early PET/CT in diffuse large B-cell lymphoma: comparison between Deauville criteria and ΔSUVmax

Purpose

The role of interim PET/CT in guiding therapeutic strategies in diffuse large B-cell lymphoma (DLBCL) is debated, mainly because interpretation rules vary among centres. This study aimed to explore the reproducibility and confirm the prognostic value of early PET/CT using the Deauville criteria and ΔSUVmax.

Methods

This international confirmatory study retrospectively evaluated 114 patients with newly diagnosed DLBCL treated with a rituximab-containing regimen. All patients underwent ¹⁸F-FDG PET/CT at baseline (PET0) and after two cycles (PET2), with no therapy change based on the latter. Scans were interpreted by three observers using the Deauville five-point scale and ΔSUVmax between PET0 and PET2 was calculated. Interpretations were evaluated for interobserver agreement and for progression-free survival (PFS) prediction.

Results

Median follow-up was 39 months. Early PET/CT was predictive of outcome when interpreted with the Deauville criteria and ΔSUVmax. Using the five-point scale, the overall kappa value was 0.66 with the reference background set in the liver (score ≥4) and interobserver agreement was even better using a 66 % ΔSUVmax cut-off (κ?=?0.83). Moreover, the prognostic value of interim PET was slightly inferior when using a Deauville score ≥4 than when using a 66 % ΔSUVmax cut-off: for the Deauville score the 3-year PFS estimate was 59 % (45–73 %) in PET2-positive patients vs. 81 % (71–91 %) in PET2-negative patients (P?=?0.003); for the 66 % ΔSUVmax cut-off the 3-year PFS estimate was 44 % (23–65 %) in PET2-positive patients vs. 79 % (70–88 %) in PET2-negative patients (P?=?0.0002).

Conclusion

Although the Deauville criteria are valid for assessing the prognostic value of early PET/CT in DLBCL, computation of the ΔSUVmax leads to better performance and interobserver reproducibility, and should be preferred when a baseline scan is available.     

Indeterminate pleural metastasis on contrast-enhanced chest CT in non-small cell lung cancer: improved differential diagnosis with 18F-FDG PET/CT

Purpose

To evaluate the diagnostic performance of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT (PET/CT) for determining the presence of pleural metastasis in patients with indeterminate findings on a contrast-enhanced chest CT (CECT) for non-small cell lung cancer (NSCLC).

Materials and methods

This is a retrospective study. NSCLC patients (n?=?63) who underwent thoracentesis and/or pleural biopsy were enrolled. CECT and PET/CT reports of pleural metastasis were analyzed based on comparison with cytological or histological confirmation. Negative cytologic results were re-confirmed with follow-up study prior to cancer-related therapy. CECT results were classified into 3 categories: negative, indeterminate, and positive for pleural metastasis. PET/CT results were classified into 2 categories (negative and positive for pleural metastasis) based on FDG uptake visual grading. The level of max SUV of pleura was also analyzed. ROC analysis was done for establishing the max SUV cut-off value.

Result

PET/CT could differentiate pleural metastasis with 70.8% diagnostic accuracy when the CECT finding was indeterminate (n?=?24). Optimal cut-off value to predict pleural metastasis was 2.8 for max SUV. Diagnosis by max SUV 2.8 had lower sensitivity (86.3 vs. 92.2%), but higher specificity (66.7 vs. 58.3%) than PET/CT by FDG visual grading criteria.

Conclusion

PET/CT showed better diagnostic performance than CECT for detecting pleural metastasis in NSCLC patients. When the finding of CECT is controversial, PET/CT can differentiate the metastatic pleural lesion. Both FDG uptake visual grading and max SUG cut-off value can be used as diagnostic criteria for pleural metastasis.     

Interim FDG-PET/CT in Hodgkin lymphoma: the prognostic role of the ratio between target lesion and liver SUVmax (rPET)

Objective

To evaluate the prognostic role of the ratio between target lesion and liver SUVmax (rPET) in patients with Hodgkin lymphoma (HL) undergoing interim FDG-PET/CT and to compare rPET with the 5-point Deauville Score (5p-DS).

Methods

Sixty-eight patients with HL undergoing interim FDG-PET/CT after first courses of chemotherapy were evaluated. The receiver operating characteristic (ROC) approach was applied to identify the optimal cutpoint of rPET with respect to progression free survival (PFS). The prognostic significance of rPET was compared with 5p-DS (scores 4 and 5 considered as positive). Positive predictive value (PPV) and negative predictive value (NPV) were calculated using the presence of an adverse event as the gold standard.

Results

The ROC analysis for rPET as a predictor of progression showed an optimal rPET cutpoint of 1.14. Both 5p-DS and rPET were strong outcome predictors (p < 0.001). Patients with negative 5p-DS and patients with rPET <1.14 had a similar two-year PFS (86 and 87 %, respectively). Patients with a positive 5p-DS had a 2-year PFS of 27 %, while patients with rPET >1.14 had a 2-year PFS of 15 %. 5p-DS and rPET cutoff of 1.14 showed a PPV of 58 versus 70 %, and a NPV of 85 versus 86 %, respectively.

Conclusions

rPET could be considered an accurate prognostic factor in patients with HL undergoing interim FDG-PET/CT. Larger prospective studies are needed to confirm these data.

     

18F-FDG PET/CT imaging versus dynamic contrast-enhanced CT for staging and prognosis of inflammatory breast cancer

Purpose

Inflammatory breast cancer (IBC) is the most aggressive type of breast cancer with a poor prognosis. Locoregional staging is based on dynamic contrast-enhanced (DCE) CT or MRI. The aim of this study was to compare the performances of FDG PET/CT and DCE CT in locoregional staging of IBC and to assess their respective prognostic values.

Methods

The study group comprised 50 women (median age: 51?±?11 years) followed in our institution for IBC who underwent FDG PET/CT and DCE CT scans (median interval 5?±?9 days). CT enhancement parameters were net maximal enhancement, net early enhancement and perfusion.

Results

The PET/CT scans showed intense FDG uptake in all primary tumours. Concordance rate between PET/CT and DCE CT for breast tumour localization was 92 %. No significant correlation was found between SUVmax and CT enhancement parameters in primary tumours (p?>?0.6). PET/CT and DCE CT results were poorly correlated for skin infiltration (kappa?=?0.19). Ipsilateral foci of increased axillary FDG uptake were found in 47 patients (median SUV: 7.9?±?5.4), whereas enlarged axillary lymph nodes were observed on DCE CT in 43 patients. Results for axillary node involvement were fairly well correlated (kappa?=?0.55). Nineteen patients (38 %) were found to be metastatic on PET/CT scan with a significant shorter progression-free survival than patients without distant lesions (p?=?0.01). In the primary tumour, no statistically significant difference was observed between high and moderate tumour FDG uptake on survival, using an SUVmax cut-off of 5 (p?=?0.7 and 0.9), or between high and low tumour enhancement on DCE CT (p?>?0.8).

Conclusion

FDG PET/CT imaging provided additional information concerning locoregional involvement to that provided by DCE CT on and allowed detection of distant metastases in the same whole-body procedure. Tumour FDG uptake or CT enhancement parameters were not correlated and were not found to have any prognostic value.     

Diagnostic value of diffusion-weighted magnetic resonance imaging (DWI) compared to FDG PET/CT for whole-body breast cancer staging

Purpose

The aim of the study was to prospectively compare the diagnostic value of whole-body diffusion-weighted imaging (DWI) and FDG PET/CT for breast cancer (BC) staging.

Methods

Twenty BC patients underwent whole-body FDG PET/CT and 1.5-T DWI. Lesions with qualitatively elevated signal intensity on DW images (b?=?800 s/mm²) were rated as suspicious for tumour and mapped to individual lesions and different compartments (overall 552 lesions). The apparent diffusion coefficient (ADC) value was determined for quantitative evaluation. Histopathology, MRI findings, bone scan findings, concordant findings between FDG PET/CT and DWI, CT follow-up scans and plausibility served as the standards of reference defining malignancy.

Results

According to the standards of reference, breasts harboured malignancy in 11, regional lymph nodes in 4, M1 lymph nodes in 3, bone in 7, lung in 2, liver in 3 and other tissues in 3 patients. On a compartment basis, the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) for the detection of malignancies were 94, 99, 98, 97 and 98% for FDG PET/CT and 91, 72, 76, 50 and 96% for DWI, respectively. Of the lesions seen on DWI only, 348 (82%) turned out to be false-positive compared to 23 (11%) on FDG PET/CT. The average lesion ADC was 820?±?300 with true-positive lesions having 929?±?252 vs 713?±?305 in false-positive lesions (p?<?0.0001).

Conclusion

Based on these initial data DWI seems to be a sensitive but unspecific modality for the detection of locoregional or metastatic BC disease. There was no possibility to quantitatively distinguish lesions using ADC. DWI alone may not be recommended as a whole-body staging alternative to FDG PET(/CT). Further studies are necessary addressing the question of whether full-body MRI including DWI may become an alternative to FDG PET/CT for whole-body breast cancer staging.     

Diagnostic accuracy of FDG PET/CT for clinical evaluation at the end of treatment of HL and NHL: a comparison of the Deauville Criteria (DC) and the International Harmonization Project Criteria (IHPC)

Purpose

To evaluate the accuracy and prognostic value of FDG PET/CT for response assessment after treatment in patients with Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) when using the Deauville Criteria (DC) and the International Harmonization Project Criteria (IHPC).

Methods

This retrospective study included 101 patients (35 HL, 66 NHL) who underwent early restaging FDG PET/CT after treatment. Scans were evaluated using the IHPC and DC. Two thresholds of positivity for the DC were used: a score of at least 3 (DC3, i.e. scores 3?–?5) and a score of at least 4 (DC4, i.e. a score of 4 or 5). Accuracy was assessed using conventional diagnostic procedures, multidisciplinary team case notes, further PET/CT scans and/or follow-up. Progression-free survival and overall survival were computed using the Kaplan-Meier method. The Cox proportional hazards model was used to identify predictors of outcome.

Results

Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FDG PET/CT for early restaging were, respectively, 92 %, 87 %, 74 %, 92 % and 86 % using DC4, 97 %, 76 %, 64 %, 98 % and 84 % using DC3, and 97 %, 67 %, 57 %, 98 % and 76 % using the IHPC. FDG PET/CT positivity was associated with a worse cumulative survival rate over a 2-year period when using DC4 in comparison with the IHPC (20 % vs. 49 %; p?<?0.05) and DC3 (47 %; p?<?0.05). Cox regression analysis showed different risks of progression in patients positive on FDG PET/CT using the IHPC, DC3 and DC4 (hazard ratios 1.57, 0.7 and 3.2, respectively).

Conclusion

FDG PET/CT using DC4 showed higher diagnostic accuracy for HL and NHL than FDG PET/CT using either the IHPC or DC3, indicating its value in predicting clinical outcome after treatment.

     

CT-based texture analysis potentially provides prognostic information complementary to interim fdg-pet for patients with hodgkin’s and aggressive non-hodgkin’s lymphomas

Objectives

The purpose of this study was to investigate the ability of computed tomography texture analysis (CTTA) to provide additional prognostic information in patients with Hodgkin's lymphoma (HL) and high-grade non-Hodgkin's lymphoma (NHL).

Methods

This retrospective, pilot-study approved by the IRB comprised 45 lymphoma patients undergoing routine 18F-FDG-PET-CT. Progression-free survival (PFS) was determined from clinical follow-up (mean-duration: 40 months; range: 10-62 months). Non-contrast-enhanced low-dose CT images were submitted to CTTA comprising image filtration to highlight features of different sizes followed by histogram-analysis using kurtosis. Prognostic value of CTTA was compared to PET FDG-uptake value, tumour-stage, tumour-bulk, lymphoma-type, treatment-regime, and interim FDG-PET (iPET) status using Kaplan-Meier analysis. Cox regression analysis determined the independence of significantly prognostic imaging and clinical features.

Results

A total of 27 patients had aggressive NHL and 18 had HL. Mean PFS was 48.5 months. There was no significant difference in pre-treatment CTTA between the lymphoma sub-types. Kaplan-Meier analysis found pre-treatment CTTA (medium feature scale, p=0.010) and iPET status (p<0.001) to be significant predictors of PFS. Cox analysis revealed that an interaction between pre-treatment CTTA and iPET status was the only independent predictor of PFS (HR: 25.5, 95% CI: 5.4-120, p<0.001). Specifically, pre-treatment CTTA risk stratified patients with negative iPET.

Conclusion

CTTA can potentially provide prognostic information complementary to iPET for patients with HL and aggressive NHL.

Key Points

? CT texture-analysis (CTTA) provides prognostic information complementary to interim FDG-PET in Lymphoma. ? Pre-treatment CTTA and interim PET status were significant predictors of progression-free survival. ? Patients with negative interim PET could be further stratified by pre-treatment CTTA. ? Provide precision surveillance where additional imaging reserved for patients at greatest recurrence-risk. ? Assists in risk-adapted treatment strategy based on interim PET and CTTA.

     

PET-CT in der nuklearmedizinischen Diagnostik des multiplen Myeloms

Background

Functional or morphofunctional imaging modalities are used in myeloma patients for the diagnosis and therapy management within research protocols. Despite new staging criteria, which take into account the viability of a myeloma lesion, positron emission tomography (PET) is not used routinely.

Objectives

The impact of PET is therefore open. The role of PET and PET computed tomography (PET-CT) for the diagnosis and therapy management is discussed.

Results

The use of PET with 18F-fluorodeoxyglucose (FDG) allows the measurement of viable myeloma lesions and correlates with the stage of disease. A negative FDG examination correlates with a better prognosis. Furthermore, the number of focal lesions as well as the whole functional volume of myeloma lesions in FDG have a prognostic impact. Several studies have demonstrated the impact of FDG for the assessment of therapy monitoring and show that FDG is an earlier indicator for therapy response as compared to magnetic resonance imaging (MRI). The CT component of the new hybrid systems allows the assessment of osteolytic lesions in CT and their viability in FDG. The combination of PET with an MRT scanner allows the simultaneous measurement of bone marrow infiltration, focal lesions and their viability.

Conclusion

The use of modern hybrid scanners, such as PET-CT and PET-MRT facilitates the simultaneous measurement of viable myeloma lesions, osteolytic lesions and bone marrow infiltration in the whole body; therefore, it is expected that these imaging modalities will play a greater role both in diagnosis and therapy management.     

The clinical utility of FDG PET/CT among solid organ transplant recipients suspected of malignancy or infection

Purpose

Solid organ transplant (SOT) recipients are at high risk of developing infections and malignancies. ¹⁸F-FDG PET/CT may enable timely detection of these diseases and help to ensure early intervention. We aimed to describe the clinical utility of FDG PET/CT in consecutive, diagnostic unresolved SOT recipients transplanted from January 2004 to May 2015.

Methods

Recipients with a post-transplant FDG PET/CT performed as part of diagnostic work-up were included. Detailed chart reviews were done to extract relevant clinical information and determine the final diagnosis related to the FDG PET/CT. Based on á priori defined criteria and the final diagnosis, results from each scan were classified as true or false, and diagnostic values determined.

Results

Among the 1,814 recipients in the cohort, 145 had an FDG PET/CT performed; 122 under the indication of diagnostically unresolved symptoms with a suspicion of malignancy or infection. The remaining (N?=?23) had an FDG PET/CT to follow-up on a known disease or to stage a known malignancy. The 122 recipients underwent a total of 133 FDG PET/CT scans performed for a suspected malignancy (66 %) or an infection (34 %). Sensitivity, specificity, and positive and negative predictive values of the FDG PET/CT in diagnosing these conditions were 97, 84, 87, and 96 %, respectively.

Conclusion

FDG PET/CT is an accurate diagnostic tool for the work-up of diagnostic unresolved SOT recipients suspected of malignancy or infection. The high sensitivity and NPV underlines the potential usefulness of PET/CT for excluding malignancy or focal infections in this often complex clinical situation.

     

<Superscript>18</Superscript>F-FDG PET/CT for the Diagnosis of Malignant and Infectious Complications After Solid Organ Transplantation

Purpose

Infection and malignancy represent two common complications after solid organ transplantation, which are often characterized by poorly specific clinical symptomatology. Herein, we have evaluated the role of ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) in this clinical setting.

Methods

Fifty-eight consecutive patients who underwent FDG PET/CT after kidney, lung or heart transplantation were included in this retrospective analysis. Twelve patients underwent FDG PET/CT to strengthen or confirm a diagnostic suspicion of malignancies. The remaining 46 patients presented with unexplained inflammatory syndrome, fever of unknown origin (FUO), CMV or EBV seroconversion during post-transplant follow-up without conclusive conventional imaging. FDG PET/CT results were compared to histology or to the finding obtained during a clinical/imaging follow-up period of at least 6 months after PET/CT study.

Results

Positive FDG PET/CT results were obtained in 18 (31 %) patients. In the remaining 40 (69 %) cases, FDG PET/CT was negative, showing exclusively a physiological radiotracer distribution. On the basis of a patient-based analysis, FDG PET/CT’s sensitivity, specificity, PPV and NPV were respectively 78 %, 90 %, 78 % and 90 %, with a global accuracy of 86 %. FDG PET/CT was true positive in 14 patients with bacterial pneumonias (n?=?4), pulmonary fungal infection (n?=?1), histoplasmosis (n?=?1), cutaneous abscess (n?=?1), inflammatory disorder (sacroiliitis) (n?=?1), lymphoma (n?=?3) and NSCLC (n?=?3). On the other hand, FDG PET/CT failed to detect lung bronchoalveolar adenocarcinoma, septicemia, endocarditis and graft-versus-host disease (GVHD), respectively, in four patients. FDG PET/CT contributed to adjusting the patient therapeutic strategy in 40 % of cases.

Conclusions

FDG PET/CT emerges as a valuable technique to manage complications in the post-transplantation period. FDG PET/CT should be considered in patients with severe unexplained inflammatory syndrome or FUO and inconclusive conventional imaging or to discriminate active from silent lesions previously detected by conventional imaging particularly when malignancy is suspected.

     

Diagnostic and prognostic impact of 18F-FDG PET/CT in follicular lymphoma

Purpose

The aim of this study was to assess the usefulness of positron emission tomography/computed tomography in staging, prognosis evaluation and restaging of patients with follicular lymphoma.

Methods

A retrospective study was performed on 45 patients with untreated biopsy-proven follicular lymphoma who underwent ¹⁸F-fluorodeoxyglucose PET/CT (FDG PET/CT) and CT before and after chemoimmunotherapy induction treatment (rituximab combined with cyclophosphamide, doxorubicin, vincristine and prednisone).

Results

PET/CT detected more nodal (+51%) and extranodal (+89%) lesions than CT. PET/CT modified Ann Arbor staging in eight patients (18%). Five patients (11%) initially considered as being early stage (I/II) were eventually treated as advanced stage (III/IV). In this study, an initial PET/CT prognostic score was significantly more accurate than the Follicular Lymphoma International Prognostic Index score in identifying patients with poor prognosis (i.e. patients with incomplete therapeutic response or early relapse). The accuracy of PET/CT for therapeutic response assessment was higher than that of CT (0.97 vs 0.64), especially due to its ability to identify inactive residual masses. In addition, post-treatment PET/CT was able to predict patients’ outcomes. The median progression-free survival was 48 months in the PET/CT-negative group as compared with 17.2 months for the group with residual uptake (p?<?10^?4).

Conclusion

FDG PET/CT is useful for staging and assessing the prognosis and therapeutic response of patients with follicular lymphoma.     

Paediatric and adolescent Hodgkin lymphoma: information derived from diffuse organ uptake of 18 F-fluorodeoxyglucose on pre-treatment and on interim PET/CT

Purpose

To evaluate, in children with Hodgkin lymphoma (HL), the frequency and intensity of visually diffuse FDG uptake by selected organs at baseline (bPET) and on interim PET/CT (iPET), and to evaluate the relation between FDG uptake, metabolic response and evolution of the disease with treatment.

Patients and methods

Thirty children with HL had bPET and then iPET after two cycles of treatment, which were blind-read retrospectively. Excluding sites with focal uptake, diffuse FDG uptake by thymus, bone marrow at iliac crests, liver, spleen, and the spinal cord at the 12th thoracic vertebra (Th12) was evaluated visually using a three-point scoring method and semiquantitatively by measuring SUVmax. Visualisation of activated brown adipose tissue (BAT) was also quoted. Five children had refractory HL. Recurrence-free survival was determined for each patient. Nine patients relapsed; in 21 non-relapsing patients, the median follow-up period was 43 months (range: 28–61).

Results

On bPET, the rate of diffuse and intense (visual score?=?3) FDG uptake was 48 % in the spleen, 43 % in the spinal cord at Th12, 37 % in bone marrow, 21 % in the thymus and 7 % in BAT. At least one of those sites showed diffuse and intense FDG uptake in 77 % of patients. On iPET, a significant decrease in SUVmax was observed in thymus, iliac crest bone marrow and spleen, but not in spinal cord. In contrast, the FDG uptake by the liver significantly increased. The absence of SUVmax increase in the liver between bPET and iPET was the best criterion to predict a refractory disease (PPV?=?55 %, NPV?=?100 %). Its area under ROC (AUC) was 0.9 vs. 0.73 for five-point Deauville criteria. For prediction of relapse, two criteria were derived from the evolution of diffuse uptake between bPET and iPET: no increase in liver uptake and an increase?>?5 % in spinal cord uptake. As compared with 13 patients who matched none of those criteria, the hazard ratio (HR) for relapse was 2.1 in 13 patients who matched one criterion, and 10.3 in four patients who matched both (Kaplan-Meier analysis p?=?0.005).

Conclusion

Diffuse and intense FDG uptake by organs is frequent in children with HL on bPET. On iPET, it is frequently reduced in all sites except the liver, which may pose problems for visual quotation of the FDG intensity of HL foci. The variation of SUVmax between bPET and iPET permitted us to achieve a prediction of refractory or relapsing HL that was at least as effective as using criteria based on FDG uptake by the HL lesions. The results of this retrospective pilot study need further validation.