Applications of PET in Diagnosis and Prognosis of Leukemia

18 F-FDG PET/CT Finding of Bilateral Breast Relapse in a Male Acute Lymphoblastic Leukemia Patient

ABSTRACT

Extramedullary relapse with involvement of the breasts by acute lymphoblastic leukemia is rare. Herein, we report a case of bilateral breast relapse of acute B-cell lymphoblastic leukemia in a man detected by 18 F-FDG PET/CT. After systematic therapy, follow-up PET/CT showed a complete response of the bilateral breasts and the axillary lymph nodes.

Clinical value of 18F-FDG PET/CT in patients with newly diagnosed acute leukemia

PURPOSE

To explore the correlation between semi-quantitative parameters of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scans findings and the clinical features of patients with acute leukemia (AL), as well as to evaluate the clinical utility of 18F-FDG PET/CT in the management of AL.

METHODS

A retrospective study was conducted with 44 patients newly diagnosed with acute leukemia (AL) at Zhongnan Hospital of Wuhan University between January 2019 and August 2024.

RESULTS

Multivariate analysis revealed that age at diagnosis of AL (odds ratio [OR]: 0.888, P < 0.01) and percentage of blasts in the peripheral blood (PB) (OR: 1.061, P < 0.05) were independent predictors of the appearance of active extramedullary disease (EMD). Kaplan-Meier survival analysis for patients with EMD(+) indicated that those with organ infiltration beyond the lymph nodes experienced markedly reduced overall survival (OS) compared to those without such infiltration (157 days and 806 days, respectively). Furthermore, in the AL subgroup with EMD, the ratio of the maximum standardized uptake value (SUVmax) in the bone marrow (BM) to SUVmax of the liver emerged as an independent prognostic factor for OS (Hazard ratio [HR]: 2.372; 95% confidence interval [CI]: 1.079-5.214, P < 0.05).

CONCLUSION

18F-FDG PET/CT offers the benefits of being non-invasive and highly sensitive for the thorough evaluation of disease status in patients newly diagnosed with AL. Furthermore, the SUVmax BM/liver ratio is of significant clinical importance for prognosticating outcomes in patients with AL presenting EMD.

Beyond the Marrow: Unveiling Uncommon Sites of ALL Relapse with 18 F-FDG PET/CT

Extramedullary infiltration of acute lymphoblastic leukemia/lymphoma (ALL) to genital organs is extremely rare. Here, we present a case report of an asymptomatic 49-year-old female, known case of precursor B-cell ALL, who was incidentally detected with thickened and heterogeneously hyperechoic endometrium on sonography. Contrast magnetic resonance imaging detected large polypoidal enhancing lesions showing intense diffusion restriction occupying the endometrial cavity and similar lesions in the left adnexa, left ovary, and fallopian tube which were suspicious for leukemic infiltration because of the clinical history and atypical appearance of the lesions. 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) was done which revealed intensely metabolically active lesion in the endometrial cavity, left adnexa, omental nodules, retroperitoneal lymph node, pancreatic lesion, and few irregular nodules in the right lower lobe. Biopsy findings confirmed extramedullary relapse of ALL. Hence, 18 F-FDG PET/CT can act as a good whole body survey to look for extramedullary sites of relapse.

Role of Novel Quantitative Imaging Techniques in Hematological Malignancies

Hematological malignancies exhibit a widespread distribution, necessitating evaluation of disease activity over the entire body. In clinical practice, visual analysis and semiquantitative parameters are used to assess 18F-FDGPET/CT imaging, which solely represents measurements of disease activity from limited area and may not adequately reflect global disease assessment. An efficient method for assessing the global disease burden of hematological malignancies is to employ PET/computed tomography based novel quantitative parameters. In this article, we explored novel quantitative parameters on PET/CT imaging for assessing global disease burden and the potential role of artificial intelligence (AI) to determine these parameters in evaluation of hematological malignancies.

Applications of 18F-Fluorodesoxyglucose PET Imaging in Leukemia

The main finding that 18F-FDG PET imaging can reveal in patients with leukemias is the presence of bone marrow (BM) infiltration in both acute or chronic forms. This ability can influence and guide the use of BM biopsy but also assess to therapy response. Additionally 18F-FDG PET imaging has been reported as particularly useful for the diagnosis of leukemias in patients with non specific symptoms. In the case of acute leukemias it revealed also a role for the evaluation of extramedullary forms while in the case of chronic forms a role for the assessment of Richter transformation has been reported.

Case report: 18F-FDG PET/CT skeletal superscan-like in an adult patient with acute lymphoblastic leukemia

We herein describe a rare case of adult acute lymphoblastic leukemia with an 18florine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) skeletal superscan-like appearance. The degree of bone marrow uptake was so intense that it far exceeded the level of physiological cerebral uptake and radiourinary activity. The distribution was remarkably similar to a superscan seen on skeletal scintigraphy. Skeletal superscans of 18F-FDG PET/CT have been reported in hematological diseases, solid tumors with extensive bone metastasis, and metabolic diseases. Thus, we reviewed the PET/CT images of cases reported, indicating that more homogeneous distribution, without primary tumor and specific mandibular and skull activity, may be suggestive of hematological diseases.

PET/CT in leukemia: utility and future directions

2-Deoxy-2-[ 18 F]fluoro- d -glucose PET/computed tomography ([ 18 F]FDG PET/CT) has proven to be a sensitive method for the detection and evaluation of hematologic malignancies, especially lymphoma. The increasing incidence and mortality rates of leukemia have raised significant concerns. Through the utilization of whole-body imaging, [ 18 F]FDG PET/CT provides a thorough assessment of the entire bone marrow, complementing the limited insights provided by biopsy samples. In this regard, [ 18 F]FDG PET/CT has the ability to assess diverse types of leukemia The utilization of [ 18 F]FDG PET/CT has been found to be effective in evaluating leukemia spread beyond the bone marrow, tracking disease relapse, identifying Richter's transformation, and assessing the inflammatory activity associated with acute graft versus host disease. However, its role in various clinical scenarios in leukemia remains unacknowledged. Despite their less common use, some novel PET/CT radiotracers are being researched for potential use in specific scenarios in leukemia patients. Therefore, the objectives of this review are to provide a thorough assessment of the current applications of [ 18 F]FDG PET/CT in the staging and monitoring of leukemia patients, as well as the potential for an expanding role of PET/CT in leukemia patients.

Nanoparticle-Based Approaches for Treatment of Hematological Malignancies: a Comprehensive Review

Blood cancer, also known as hematological malignancy, is one of the devastating types of cancer that has significantly paved its mortality mark globally. It persists as an extremely deadly cancer type and needs utmost attention owing to its negligible overall survival rate. Major challenges in the treatment of blood cancer include difficulties in early diagnosis, as well as severe side effects resulting from chemotherapy. In addition, immunotherapies and targeted therapies can be prohibitively expensive. Over the past two decades, scientists have devised a few nanoparticle-based drug delivery systems aimed at overcoming this challenge. These therapeutic strategies are engineered to augment the cellular uptake, pharmacokinetics, and effectiveness of anticancer drugs. However, there are still numerous types of nanoparticles that could potentially improve the efficacy of blood cancer treatment, while also reducing treatment costs and mitigating drug-related side effects. To the best of our knowledge, there has been limited reviews published on the use of nano-based drug delivery systems for the treatment of hematological malignancies. Therefore, we have made a concerted effort to provide a comprehensive review that draws upon recent literature and patents, with a focus on the most promising results regarding the use of nanoparticle-based approaches for the treatment of hematological malignancies. All these crucial points covered under a common title would significantly help researchers and scientists working in the area.

Role of peripheral blood MRD and 18F-FDG PET in the post-CAR relapse setting: a case study of discordant peripheral blood and bone marrow MRD

BACKGROUND

Chimeric antigen receptor (CAR) T cell therapy is an effective salvage therapy for pediatric relapsed B-cell acute lymphoblastic leukemia (B-ALL), yet is challenged by high rates of post-CAR relapse. Literature describing specific relapse patterns and extramedullary (EM) sites of involvement in the post-CAR setting remains limited, and a clinical standard for post-CAR disease surveillance has yet to be established. We highlight the importance of integrating peripheral blood minimal residual disease (MRD) testing and radiologic imaging into surveillance strategies, to effectively characterize and capture post-CAR relapse.

MAIN BODY

Here, we describe the case of a child with multiply relapsed B-ALL who relapsed in the post-CAR setting with gross non-contiguous medullary and EM disease. Interestingly, her relapse was identified first from peripheral blood flow cytometry MRD surveillance, in context of a negative bone marrow aspirate (MRD <0.01%). Positron emission tomography with 18F-fluorodeoxyglucose revealed diffuse leukemia with innumerable bone and lymph node lesions, interestingly sparing her sacrum, the site of her bone marrow aspirate sampling.

CONCLUSIONS

We highlight this case as both peripheral blood MRD and 18F-fluorodeoxyglucose positron emission tomography imaging were more sensitive than standard bone marrow aspirate testing in detecting this patient's post-CAR relapse. Clinical/Biologic Insight: In the multiply relapsed B-ALL setting, where relapse patterns may include patchy medullary and/or EM disease, peripheral blood MRD and/or whole body imaging, may carry increased sensitivity at detecting relapse in patient subsets, as compared with standard bone marrow sampling.

PET-CT in Clinical Adult Oncology: I. Hematologic Malignancies

PET-CT is an advanced imaging modality with many oncologic applications, including staging, assessment of response to therapy, restaging and evaluation of suspected recurrence. The goal of this 6-part series of review articles is to provide practical information to providers and imaging professionals regarding the best use of PET-CT for the more common adult malignancies. In the first article of this series, hematologic malignancies are addressed. The classification of these malignancies will be outlined, with the disclaimer that the classification of lymphomas is constantly evolving. Critical applications, potential pitfalls, and nuances of PET-CT imaging in hematologic malignancies and imaging features of the major categories of these tumors are addressed. Issues of clinical importance that must be reported by the imaging professionals are outlined. The focus of this article is on [¹⁸F] fluorodeoxyglucose (FDG), rather that research tracers or those requiring a local cyclotron. This information will serve as a resource for the appropriate role and limitations of PET-CT in the clinical management of patients with hematological malignancy for health care professionals caring for adult patients with hematologic malignancies. It also serves as a practical guide for imaging providers, including radiologists, nuclear medicine physicians and their trainees.

Characterization of Extramedullary Disease in B-ALL and Response to CAR T-cell Therapy

A substantial fraction of patients with relapsed/refractory B-ALL will have non-CNS EMD.

CAR T cells may have limited efficacy in multifocal non-CNS EMD, and serial imaging is needed to identify and monitor EMD.

Chimeric antigen receptor (CAR) T cells effectively eradicate medullary B-cell acute lymphoblastic leukemia (B-ALL) and can traffic to and clear central nervous system (CNS) involvement. CAR T-cell activity in non-CNS extramedullary disease (EMD) has not been well characterized. We systematically evaluated CAR T-cell kinetics, associated toxicities, and efficacy in B-ALL non-CNS EMD. We conducted a retrospective review of B-ALL patients with non-CNS EMD who were screened for/enrolled on one of three CAR trials (CD19, CD22, and CD19/22) at our institution. Non-CNS EMD was identified according to histology or radiographic imaging at extramedullary sites excluding the cerebrospinal fluid and CNS parenchyma. Of ∼180 patients with relapsed/refractory B-ALL screened across multiple early-phase trials over an 8-year period, 38 (21.1%) presented with isolated non-CNS EMD (n = 5) or combined medullary/non-CNS EMD (n = 33) on 18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging. A subset receiving CAR T cells (18 infusions) obtained FDG PET/CT scans preinfusion and postinfusion to monitor response. At best response, 72.2% (13 of 18) of patients showed a medullary minimal residual disease–negative complete remission and complete (n = 7) or partial (n = 6) non-CNS EMD response. Non-CNS EMD responses to CAR T cells were delayed (n = 3), and residual non-CNS EMD was substantial; rarely, discrepant outcomes (marrow response without EMD response) were observed (n = 2). Unique CAR-associated toxicities at non-CNS EMD sites were seen in select patients. CAR T cells are active in B-ALL non-CNS EMD. Still, non-CNS EMD response to CAR T cells may be delayed and suboptimal, particularly with multifocal disease. Serial FDG PET/CT scans are necessary for identifying and monitoring non-CNS EMD.

Kidney Failure and Abdominal Discomfort as Initial Signs of Extramedullary Acute Myelogenous Leukemia

Although rare, acute myelogenous leukemia (AML) can include extramedullary manifestations, sometimes presenting as a solid tumor called a myeloid sarcoma. Myeloid sarcoma can be the cause of the initial presenting complaint before AML diagnosis, or may be detected as a sign of disease-relapse after treatment. Here, we report a case in which the initial presentation included abdominal discomfort and signs of kidney failure. Further investigation revealed signs of unilateral hydronephrosis. Due to a diagnostic delay, the patient was diagnosed with AML with extramedullary manifestation only after the development of full-blown leukemia. Biopsy of the compressive tumor confirmed an extramedullary myeloid sarcoma, and [¹⁸F]-FDG-PET/CT proved useful for patient diagnosis and follow-up. This case report illustrates the importance of thorough examination and diagnosis, as a serious underlying disease with a rare cause can debut with an unusual presentation.