Current status of PET/CT in the diagnosis and follow up of lymphomas

Cross-sectional imaging evaluation of atypical and uncommon extra-nodal head and neck Non-Hodgkin lymphoma: Case series

Extra-nodal Non-Hodgkin lymphoma (ENHL) of the head and neck is not uncommon and has variable clinical and imaging presentations. It represents about 25% of extra-nodal lymphomas. In addition, lymphoma is the third most common malignancy of the head and neck just after squamous cell carcinoma (SCC) and salivary gland neoplasms. Unlike SCC, ENHL usually presents as a well-defined mass in the oral cavity, along the pharyngeal mucosa, sinonasal cavity, orbit, and other different neck spaces. One of the common presentations of ENHL is the glandular type which can arise within the salivary or thyroid glands as marginal zone non-Hodgkin lymphoma. ENHL can infiltrate the bone resembling high grade osseous malignancies. Rarely, ENHL can present as perineural spread without definitive mass and manifest clinically with several neuropathies. In this case series, we presented different imaging features and presentation of ENHL of the head and neck. The knowledge of various presentations of ENHL of the head and neck can help early diagnosis and prompt management of these patients' population.

Diffuse Large B-Cell Non-Hodgkin Lymphoma Involving Multiple Different Organs in a Young Adult with 18F-FDG PET/CT

Extranodal-multiorgan involvement is rarely presented in diffuse large B-cell non-Hodgkin lymphoma. ¹⁸Fluorine-fluorodeoxyglucose positron emission tomography/computed tomography findings of a 22-year-old female patient with supra/infra-diaphragmatic nodal and skeletal involvements and thyroid, pancreas, right breast, bilateral renal, and ovarian involvements were presented.

Role of PET/CT in initial evaluation of lymphoma patients

Background

Accurate radiologic assessment of treatment response in lymphoma patients is important to evaluate the effectiveness of treatment and consequently predict the relapse; the value of PET/CT for post-treatment prognosis prediction has been recently investigated. The aim of this study is to highlight the prognostic value of PET-CT metabolic volumetric parameters in the evaluation of lymphoma patients.

Results

Among the included 40 patients, post-treatment SUV, MTV, and TLG were significantly lower in a responsive group than the non-responsive group. % changes of all quantitative PET/CT parameters were significantly higher in the responsive group than the non-responsive group.

Conclusions

This study suggests that pre-treatment PET/CT quantitative measures (except baseline SUVmax) are not conclusive in the prediction of patient response to treatment; however, the ΔSUVmax, ΔMTV, and ΔTLG% from the baseline to the end of therapy could be used in predicting patient response to treatment, determining patient prognosis, and suggesting the relapse.

Role of PET/CT in initial evaluation of lymphoma patients

Background

Accurate radiologic assessment of treatment response in lymphoma patients is important to evaluate the effectiveness of treatment and consequently predict the relapse; the value of PET/CT for post-treatment prognosis prediction has been recently investigated. The aim of this study is to highlight the prognostic value of PET-CT metabolic volumetric parameters in the evaluation of lymphoma patients.

Results

Among the included 40 patients, post-treatment SUV, MTV, and TLG were significantly lower in a responsive group than the non-responsive group. % changes of all quantitative PET/CT parameters were significantly higher in the responsive group than the non-responsive group.

Conclusions

This study suggests that pre-treatment PET/CT quantitative measures (except baseline SUVmax) are not conclusive in the prediction of patient response to treatment; however, the ΔSUVmax, ΔMTV, and ΔTLG% from the baseline to the end of therapy could be used in predicting patient response to treatment, determining patient prognosis, and suggesting the relapse.

Case Report: Spontaneous Remission of an Infraorbital Follicular B-Cell Lymphoma: Case Report and Review of the Literature

Non-Hodgkin lymphomas comprise a heterogeneous group of malignancies, with a wide scope of clinical, radiological and histological presentations. In this paper, a case is presented of a 59-year-old white male with an infraorbital follicular B-cell lymphoma, which appeared as a painless mass in the left cheek. The lymphoma achieved spontaneous remission five and a half months after his diagnostic incision biopsy. The literature is reviewed, focusing on this rare site of presentation and spontaneous remission. In literature, only four cases have been reported with a follicular B-cell lymphoma of the cheek or infraorbital region, and only 26 cases of spontaneous remission of an extracranial non-Hodgkin lymphoma in the head and neck region have been described. To the authors’ best knowledge, this is the first time spontaneous remission of an infraorbital follicular lymphoma could be observed. The nature of the processes inducing spontaneous remission remains obscure. It is important to recognize this phenomenon as this might prevent unnecessary treatment.

The presence of a bulky mediastinal mass of 7 cm or greater in diameter confers an adverse prognosis to patients with advanced Hodgkin lymphoma in case of negative interim PET/CT

In the PET-adapted therapy era, a bulky mediastinal mass (BMM) is not considered a risk factor in patients with advanced-stage Hodgkin lymphoma (HL). The current retrospective study aimed to estimate the prognostic significance of BMM presence and size for disease-free survival (DFS) and determine the most accurate mass size cutoff (among 5 cm, 7 cm, 10 cm) to predict inferior DFS in such patients. The study included 196 advanced-HL patients treated at Rambam (n = 121) and Memorial Sloan Kettering Cancer Center (n = 75) between 2002 and 2016. At a median follow-up of 66.5 (1-222) months, 36 relapses occurred. In multivariate analysis, only the cutoff of 7 cm predicted inferior DFS and PFS (p < 0.007 and <0.038, respectively) in interim PET/CT (PET-2) negative (79%) patients. This study identifies the BMM size cutoff of 7 cm in any plane as most precise in predicting adverse prognosis in PET-2-negative patients with advanced-stage HL. More aggressive initial chemotherapy than ABVD improves such prognosis.

PET/CT and contrast-enhanced CT: making a difference in assessment and staging of patients with lymphoma

Background

The aim of this study is to evaluate the diagnostic performance of contrast-enhanced computed tomography (CECT) and 2-[Fluorine-18] fluoro-2-deoxy-d-glucose positron emission tomography combined to computed tomography (18 F-FDG PET/CT) in assessment of lymphoma.

Methods

Hundred patients, pathologically proven as lymphoma, were evaluated by CECT and 18F-FDG PET/CT for initial assessment and staging of the disease. The number of lesions and the disease stage detected by each modality was calculated and further analyzed to be compared.

Results

18F-FDG PET/CT diagnosed a total number of 545 lymphoma involved regions with sensitivity 96.6%, specificity 98.8%, and accuracy 99% that was higher than CECT which diagnosed a total number of 439 lymphomatous regions with sensitivity 87.5%, specificity 85.7%, and accuracy 88%. Discordant staging by both modalities was found in 23% of the patients. Lymphoma was upstaged by PET/CT in 17% of the patients; with major changes in 12% of them and downstaged in 6% of the patients.

Conclusion

18F-FDG PET/CT scan has a better diagnostic performance, represented by sensitivity, specificity, and accuracy, than CECT scan in the initial assessment of lymphoma regarding its nodal and extra-nodal lesions that could lead to alteration of disease staging which in turn markedly affecting the decision of treatment regimens.

Correlation of texture feature analysis with bone marrow infiltration in initial staging of patients with lymphoma using 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography

Purpose

To explore whether radiomic features of fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomo-graphy-computed tomography (PET/CT) has association with bone marrow infiltration (BMI) in comparison to other conventional PET metrics.

Material and methods

Forty-four patients (with pathologically proven lymphoma disease) underwent staging ¹⁸F-FDG PET/CT scan. Primary tumour was semi-automatically or manually segmented with a threshold standardised uptake value (SUV) of 3. A total of 73 features were extracted from eight different textures. Spearman correlation was used to test the correlation of features with conventional quantitative metrics such as SUV, metabolic tumour volume, and total lesion glycolysis. Specificity and sensitivity (including 95% confidence intervals [CI]) for each of the studied parameters were derived using receiver operative characteristic (ROC) curves. Univariate and multivariate analyses were used to identify independent predictors associated with BMI.

Results

Correlation between conventional PET metrics and features ranged between 0.50 and 0.97 for positive correlation (33 significant association features) and ranged from -0.52 to -0.97 for inverse correlation (three significant association features) for both strong and moderate correlations. Analysis of ROC curves showed that high-intensity long-run emphasis 4 bin, high-intensity large zone emphasis 64 bin, long-run emphasis (LRE) 64 bin, large-zone emphasis 64 bin, max spectrum 8 bin, busyness 64 bin, and code similarity 32 and 64 bin were significant discriminators of BMI among other features (area under curve > 0.682, p < 0.05). Univariate analyses of texture features showed that code similarity and long-run emphasis (both 64 bin) were significant predictors of bone marrow involvement. Multivariate analyses revealed that LRE (64 bin, p = 0.031) with an odds ratio of 1.022 and 95% CI of (1.002-1.043) were independent variables for bone marrow involvement.

Conclusions

¹⁸F-FDG PET/CT radiomic features are synergistic to visual assessment of BMI in patients diagnosed with lymphoma using ¹⁸F-FDG PET/CT. Further assessment of long-run emphasis is highly warranted.

Diagnostic approach in hepatic lymphoma: radiological imaging findings and literature review

PURPOSE

Imaging manifestations of hepatic lymphoma, both primary (PHL) and secondary (SHL), are extremely variable and non-specific, but some features are useful diagnostic clues in an appropriate clinical setting. Through a PubMed search, we found several published reviews focused on PHL and SHL diagnosis. However, to the best of our knowledge, few of them encompass a comprehensive analysis of all the diagnostic tools and relative radiological findings. The aim of this review is to provide a description of the radiological features of both PHL and SHL, by critically analyzing the available literature.

MATERIALS AND METHODS

An extensive review of published literature along with a description of personal case series of both PHL and SHL has been conducted.

RESULTS

SHL can be easily diagnosed with imaging techniques, as it is usually associated with node disease. On the contrary the diagnosis can be a challenge in PHL, often mimicking HCC or liver metastasis of adenocarcinoma. In this context, multiparametric MRI plays a fundamental role in the differential diagnosis. Both for PHL and SHL, liver involvement presents as solitary or multiple lesions or as diffuse infiltrative disease.

CONCLUSION

PHL and SHL may be correctly characterized using different radiological techniques. Both CT and MRI have showed a good correlation with histology, as they permit to distinguish between lymphomatous tissue, and necrotic and fibrotic areas.

Early Detection of Secondary Central Nervous System Lymphoma on PET/CT

We present a case of secondary central nervous system relapse of lymphoma detected initially on PET/CT without corresponding findings on MRI. A 60-year-old lymphoma patient demonstrated an FDG-avid focus in left cerebellar hemisphere on restaging PET/CT. MRI brain showed no corresponding abnormality, and expectant management ensued. Six months later, she represented with metabolic progression of previously seen FDG-avid focus in left cerebellar hemisphere, now also manifesting as an enhancing mass on MRI. Posttreatment scan for presumed lymphoma relapse showed metabolic response. This case demonstrates the advantage of PET/CT over anatomical imaging to detect metabolic changes before structural changes become apparent.

MRD response in relapsed/refractory FL after obinutuzumab plus bendamustine or bendamustine alone in the GADOLIN trial

We report assessment of minimal residual disease (MRD) status and its association with outcome in rituximab-refractory follicular lymphoma (FL) in the randomized GADOLIN trial (NCT01059630). Patients received obinutuzumab (G) plus bendamustine (Benda) induction followed by G maintenance, or Benda induction alone. Patients with a clonal marker (t[14;18] translocation and/or immunoglobulin heavy or light chain rearrangement) detected at study screening were assessed for MRD at mid-induction (MI), end of induction (EOI), and every 6–24 months post-EOI/discontinuation by real-time quantitative PCR. At MI, 41/52 (79%) patients receiving G-Benda were MRD-negative vs. 17/36 (47%) patients receiving Benda alone (p = 0.0029). At EOI, 54/63 (86%) patients receiving G-Benda were MRD-negative vs. 30/55 (55%) receiving Benda alone (p = 0.0002). MRD-negative patients at EOI had improved progression-free survival (HR, 0.33, 95% CI, 0.19–0.56, p < 0.0001) and overall survival (HR, 0.39, 95% CI, 0.19–0.78, p = 0.008) vs. MRD-positive patients, and maintained their MRD-negative status for longer if they received G maintenance than if they did not. These results suggest that the addition of G to Benda-based treatment during induction can significantly contribute to the speed and depth of response, and G maintenance in MRD-negative patients potentially delays lymphoma regrowth.

Development and internal validation of a risk scoring system for gastrointestinal events requiring surgery in gastrointestinal lymphoma patients

BACKGROUND AND AIM

The predictors of severe gastrointestinal (GI) events in GI lymphoma patients are unclear. We aimed to develop a risk scoring system for GI events requiring surgery.

METHODS

In this retrospective study of 192 patients with GI lymphoma, the state of lymphoma, macroscopic findings, examination results, and International Prognostic Index were assessed. We developed a risk score for GI events that required surgery and assessed its accuracy by calculating the area under the receiver operating characteristic curve (AUC). Internal validation was performed using bootstrap resampling.

RESULTS

Severe GI events occurred in 21 (11%) patients. We developed a 4-point scoring system (the FLASH score) comprising the following three independent predictors (weighted by regression coefficients): (i) focal appearance and large size (≥ 40 mm), 1 point; (ii) aggressive lymphoma of the small bowel, 2 points; and (iii) high (18)F-fluorodeoxyglucose positron emission tomography uptake, 1 point. The score predicted severe GI events with an AUC value of 0.91 (internal validation; AUC, 0.86). Risk was classified into three categories: the GI event rate was 0% in the low-risk group (0 points), 9% in the intermediate-risk group (1-2 points), and 61% in the high-risk group (3-4 points) (AUC, 0.89).

CONCLUSIONS

We developed and internally validated a risk scoring system (the FLASH score) that included macroscopic findings to predict severe GI events in GI lymphoma patients. Patients with high scores are candidates for elective surgery to prevent GI events.

Multi-b value diffusion-weighted magnetic resonance imaging and intravoxel incoherent motion modeling: Differentiation of aggressive lymphoma lesions on initial treatment and activity assessment after chemotherapy

The diagnostic efficiency of diffusion-weighted magnetic resonance imaging with different b-values and application of an intravoxel incoherent motion (IVIM) model for differentiating disease states of lymphoma was investigated.Thirty-six patients at initial diagnosis and 69 after chemotherapy underwent diffusion-weighted magnetic resonance imaging (DW-MRI) with multiple b-values. Analysis parameters included the apparent diffusion coefficient (ADC) for each b-value. Standard ADC, D, D*, and f were calculated using an IVIM model.For patients at initial diagnosis, compared with aggressive lymphomas, the benign lymph nodes exhibited higher mean ADC (2.34 vs 0.66 × 10 mm/s, P < .01) for b = 200 s/mm. The AUC, sensitivity, specificity, and the cutoff value were 0.992, 96%, 100%, and 1.09 ×10 mm/s, respectively. For patients who had finished chemotherapy, the f-values of IVIM for those with partial remission (PR) were higher than those of complete remission (CR) (56.22 vs 21.81%, P < .01). The AUC, sensitivity, specificity, and the cutoff value were 0.937, 94%, 82%, 42.10%, respectively.For b = 200 s/mm, ADC values are most helpful for characterizing benign lymph nodes and malignant lymphomas. The f-value of the IVIM is most valuable in the identification of residual lesions of lymphomas after chemotherapy.

Low rate of spleen involvement in sporadic Burkitt lymphoma at staging on PET-CT

BACKGROUND

Burkitt lymphoma is a highly aggressive B cell non-Hodgkin lymphoma. Cross-sectional imaging techniques that are used to detect liver and spleen involvement by lymphoma have high rates of false negative and false positive findings, and as such may reduce the accuracy of staging.

PURPOSE

This retrospective study evaluated the use of FDG PET-CT in determining splenic involvement at staging, in a relatively large cohort of adult patients with the sporadic form of Burkitt lymphoma (SBL).

PATIENTS AND METHODS

All adult patients who underwent FDG PET-CT for staging of SBL at one medical center during 2005-2014 were enrolled for this retrospective study.

RESULTS

Data were analyzed of 20 patients, with median age 49 years; 17 were male. PET-CT revealed highly intense FDG uptake, mean SUV max 11.4 ± 7.49 (range 4.3-38) in various tissues. None of the 20 patients had either focal or diffuse increased uptake of FDG in the spleen parenchyma. In 2 patients, there were highly FDG-avid soft tissue masses adjacent to the spleen, both in the context of direct peritoneal disease extension.

CONCLUSION

The spleen is rarely involved in SBL at the time of staging, according to PET-CT, except in cases with direct extension from adjacent peritoneal mass. The low rate of spleen involvement according to PET-CT may serve as a specific characteristic of SBL. Larger-scale clinical studies incorporating PET-CT scans in SBL are needed to confirm our observation.

Metachronous presentation of small-cell rectal carcinoma on an 18F-FDG PET/CT follow-up for follicular lymphoma

We present a case of a 60-year-old woman with history of follicular lymphoma in remission presenting for an 18F-fluorodeoxyglucose positron emission tomography/computed tomography for suspected recurrence. Imaging showed widespread hypermetabolic lymphadenopathy consistent with lymphoma recurrence. A 3-month 18F-fluorodeoxyglucose positron emission tomography/computed tomography follow-up after chemotherapy showed resolution of hypermetabolic lymphadenopathy but multiple new hepatic lesions and a new subtle rectal lesion. Biopsies of both hepatic and rectal lesions revealed new diagnosis of metachronous high-grade small-cell carcinoma.

FDG PET-CT evaluation in neurolymphomatosis: imaging characteristics and clinical outcomes

Neurolymphomatosis (NL) often represents unidentified non-Hodgkin lymphoma relapses. Considering its severity, early detection and treatment are crucial. We outline one hospital's ¹⁸F-FDG-PET-CT imaging findings of NL, along with the patients' clinical characteristics. Clinical records and imaging findings of 19 NL patients, PET-CT diagnosed, were retrospectively reviewed. Patient data, FDG-PET-CT findings and the presence of coexisting diseases, especially CNS involvement, were documented. Available MRI and clinical data verified the findings. All cases had increased linear FDG uptake along anatomic nerve sites. CTs showed varying degrees of corresponding soft-tissue-thickening. Clinical correlations also contributed to the diagnosis. In 4/19 patients, lymphoma presented with NL, in 15/19 it appeared with disease recurrence/progression. In 9/19, clinical symptoms suggested neural involvement while 10/19 had nonspecific symptoms. Eleven died of lymphoma within 0.9 years of diagnosis despite directed-therapy. Eight, however, survived up to 7.82 years post-diagnosis. Whole-body FDG-PET-CT can assist in early NL diagnosis, possibly enhancing survival.

Feasibility of a multimodal (18)F-FDG-directed lymph node surgical excisional biopsy approach for appropriate diagnostic tissue sampling in patients with suspected lymphoma

Background

¹⁸F-FDG PET/CT imaging is widely utilized in the clinical evaluation of patients with suspected or documented lymphoma. The aim was to describe our cumulative experience with a multimodal ¹⁸F-FDG-directed lymph node surgical excisional biopsy approach in patients with suspected lymphoma.

Methods

Thirteen patients (mean age 51 (±16;22–76) years), with suspected new or suspected recurrent lymphoma suggested by ¹⁸F-FDG-avid lesions seen on prior diagnostic whole-body PET/CT imaging, were injected IV with ¹⁸F-FDG prior to undergoing same-day diagnostic lymph node surgical excisional biopsy in the operating room. Various ¹⁸F-FDG detection strategies were used on the day of surgery, including, (1) same-day pre-resection patient PET/CT; (2) intraoperative gamma probe assessment; (3) clinical scanner specimen PET/CT imaging of whole surgically excised tissue specimens; (4) specimen gamma well counts; and/or (5) same-day post-resection patient PET/CT.

Results

Same-day ¹⁸F-FDG injection dose was 14.8 (±2.4;12.5-20.6) millicuries or 548 (±89;463–762) megabecquerels. Sites of ¹⁸F-FDG-avid lesions were 4 inguinal, 3 cervical, 3 abdominal/retroperitoneal, 2 axillary, and 1 gluteal region subcutaneous tissue. Same-day pre-resection patient PET/CT was performed on 6 patients. Intraoperative gamma probe assessment was performed on 13 patients. Clinical scanner PET/CT imaging of whole surgically excised tissue specimens was performed in 10 cases. Specimen gamma well counts were performed in 6 cases. Same-day post-resection patient PET/CT imaging was performed on 8 patients. Time from ¹⁸F-FDG injection to same-day pre-resection patient PET/CT, intraoperative gamma probe assessment, and same-day post-resection patient PET/CT were 76 (±8;64–84), 240 (±63;168–304), and 487 (±104;331–599) minutes, respectively. Time from ¹⁸F-FDG injection to clinical scanner PET/CT of whole surgically excised tissue specimens was 363 (±60;272–446) minutes. Time from ¹⁸F-FDG injection to specimen gamma well counts was 591 (±96;420–689) minutes. Intraoperative gamma probe assessment successfully identified ¹⁸F-FDG-avid lesions in 12/13 patients. Histopathologic evaluation confirmed lymphoma in 12/13 patients and benign disease in 1/13 patients.

Conclusions

A multimodal approach to ¹⁸F-FDG-directed lymph node surgical excisional biopsy for suspected lymphoma is technically feasible for guiding appropriate diagnostic tissue sampling of lymph nodes seen as ¹⁸F-FDG-avid lesions on diagnostic ¹⁸F-FDG PET/CT imaging.

(18)F-FDG PET/CT in Neurolymphomatosis: Report of 3 Cases

Neurolymphomatosis is a rare manifestation of non-Hodgkin lymphoma characterized by infiltration of peripheral nerves, nerve roots, plexus and cranial nerves by malignant lymphocytes. This report presents positron emission tomography/computed tomography (PET/CT)imaging with 2-deoxy-2-(18)F-fluoro-D-glucose ((18)F-FDG) in 3 cases of non-Hodgkin lymphoma with nerve infiltration, including one newly diagnosed lymphoma, one recurrent lymphoma in previous nerve lesions and one newly recurrent lymphoma. PET/CT could reveal the affected neural structures including cranial nerves, spinal nerve roots, brachial plexus, cervicothoracic ganglion, intercostal nerves, branches of the vagus nerve, lumbosacral plexus and sciatic nerves. There was relative concordance between PET/CT and MRI in detection of affected cranial nerves. PET/CT seemed to be better than MRI in detection of affected peripheral nerves. (18)F-FDG PET/CT was a whole-body imaging technique with the ability to reveal the affected cranial nerves, peripheral nerves, nerve roots and plexus in non-Hodgkin lymphoma. A thorough understanding of disease and use of advanced imaging modalities will increasingly detect neurolymphomatosis.