Solid splenic masses: evaluation with 18F-FDG PET/CT

Diagnostic ability of [18F]FDG PET/CT for distinguishing benign from malignant spleen lesions

OBJECTIVES

[18F]Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a non-invasive imaging modality used in the differential diagnosis of splenic lesions, although ideal parameters and thresholds remain unclear. The present study evaluated the ability of [18F]FDG PET/CT, including its visual and quantitative parameters, to differentiate between benign and malignant splenic lesions.

METHODS

Patients who underwent [18F]FDG PET/CT following the detection of splenic lesions on contrast-enhanced CT were retrospectively analysed. Visual parameters assessed on [18F]FDG PET/CT included whole spleen uptake intensity, lesion multiplicity, and lesion uptake, and quantitative parameters included maximum standardised uptake value (SUVmax), lesion-to-background ratio (LBR), metabolic tumour volume (MTV), total lesion glycolysis (TLG), and lesion size. Parameters differentiating between benign and malignant lesions were evaluated by Pearson's chi-square test, Mann-Whitney U-test, and receiver operating characteristics (ROC) curve analysis.

RESULTS

Splenic lesion uptake (p = 0.001) was the only visual parameter significantly distinguishing between benign and malignant lesions. ROC curve analysis demonstrated that SUVmax had the largest area under the ROC, 0.91 (p < 0.001), with an optimal cut-off > 5.3 having a sensitivity of 90.3% and a specificity of 80.6%. Subgroup analysis of malignant lesions showed that SUVmax (p = 0.013), LBR (p = 0.012), and TLG (p  = 0.034) were significantly higher in splenic lymphomas than in splenic metastases.

CONCLUSION

Of the [18F]FDG PET/CT parameters investigated, SUVmax had the highest accuracy in diagnosing malignant splenic lesions and was significantly higher in splenic lymphomas than in splenic metastases. Visual determination of [18F]FDG uptake by splenic lesions may be an easily evaluated parameter.

CLINICAL RELEVANCE STATEMENT

SUVmax and visual grade of [18F]FDG PET/CT help to differentiate spleen lesions. [18F]FDG PET/CT is useful for discriminating between benign and malignant spleen lesions.

KEY POINTS

Many splenic lesions are difficult to diagnose on anatomical imaging, with histopathologic analyses are required. SUVmax of PET/CT provided the diagnostic ability to differentiate between benign and malignant splenic lesions. More than normal spleen uptake can be a convenient parameter to diagnose malignant spleen lesions.

Incidental Focal Spleen Lesions: Integrated Imaging and Pattern Recognition Approach to the Differential Diagnosis

Spleen lesions and pseudolesions, detected incidentally in imaging, are not uncommon and may require further work-up. The imaging appearance of focal splenic lesions (FSLs) may not be pathognomonic, because of considerably overlapping features. Consequently, all imaging techniques lack specificity to fully characterize FSLs. Clinical correlation is mandatory, so as, first of all, to categorize the patient as having or not having a history of solid or hematologic malignancy. Nowadays, many patients have old imaging studies available for comparison and, consequently, it is important to understand if the lesion was previously present or not, and if the size is the same or has changed. In the absence of comparison studies, and with a lack of imaging features of benignity, further investigation may be necessary, using PET, biopsy, or short-term follow-up. Some algorithms have been proposed to manage incidental FSLs; however, none of these strategies has been validated by prospective studies to date. In this review we illustrate the topic of incidental FSLs and we analyze a number of published algorithms.

The Spectrum of Solitary Benign Splenic Lesions-Imaging Clues for a Noninvasive Diagnosis

Cross-sectional imaging of the upper abdomen, especially if intravenous contrast has been administered, will most likely reveal any acute or chronic disease harbored in the spleen. Unless imaging is performed with the specific purpose of evaluating the spleen or characterizing a known splenic lesion, incidentally discovered splenic lesions pose a small challenge. Solitary benign splenic lesions include cysts, hemangiomas, sclerosing angiomatous nodular transformation (SANT), hamartomas, and abscesses, among others. Sarcoidosis and tuberculosis, although predominantly diffuse micronodular disease processes, may also present as a solitary splenic mass lesion. In addition, infarction and rupture, both traumatic and spontaneous, may take place in the spleen. This review aims to describe the imaging features of the most common benign focal splenic lesions, with emphasis on the imaging findings as these are encountered on routine cross-sectional imaging from a multicenter pool of cases that, coupled with clinical information, can allow a definite diagnosis.

Multimodality imaging of adrenal gland pathologies: A comprehensive pictorial review

The assessment of acute abdominal and pelvic emergencies typically involves a multimodal approach consisting of plain radiographs, ultrasound, computed tomography (CT), and rarely magnetic resonance imaging (MRI). Although MRI is not traditionally employed in acute care settings, there are several instances in which MRI provides superior functional and prognostic information. In this manuscript, we highlight multimodal findings of adrenal gland emergencies: Hemorrhage, infarction, and infection. The purpose of our study is to highlight significant findings in various modalities, including CT, MRI, ultrasound, and PET/CT. Due to the scarcity of published data and limited clinical use, primary ultrasound findings are limited in our multimodal review. In conclusion, we find that synergistic use of CT, MRI, and functional imaging provides an effective tool for evaluation and management of adrenal pathology.

Isolated Spleen Metastases of Endometrial Cancer: A Case Report

BACKGROUND

Isolated splenic metastases from endometrial cancer, which is a relatively common malignancy, are extremely rare findings; to date, only 14 cases have been reported in the literature.

CASE SUMMARY

We report a patient with isolated splenic metastases of endometrial cancer 3 years after radical surgery of the primary tumor. The patient was successfully treated by splenectomy and six cycles of paclitaxel. Fifty months after splenectomy, she was alive and well, and with no evidence of disease.

CONCLUSION

Isolated spleen metastasis of endometrial cancer is very rare. Radical surgery and adjuvant therapy may offer excellent long-term survival.

Isolated Splenic Metastasis of Primary Lung Cancer Presented as Metachronous Oligometastatic Disease—A Case Report

Modern oncology practice and new antitumor drugs prolonged disease-free intervals in patients with lung cancer. Patients with distant metastatic disease are treated only with palliative intent. The International Association for the Study of Lung Cancer, in the 8th edition of the TNM classification, for the first time includes oligometastatic disease as a clinical state that describes the patients with distant metastasis, limited in number and organ sites, who may have more indolent biology. In this paper, we present a case of a 56-year-old man who was admitted to our clinic regarding a radiologically diagnosed splenic lesion of uncertain nature, and who underwent a left upper lobectomy for primary lung cancer 12 years before. After a detailed radiological diagnosis, it was concluded that it is highly suspected metastatic lesion of the spleen and the patient underwent a splenectomy. While no definitive protocols exist on the management of isolated splenic metastasis from lung cancer, splenectomy, in suitable patients, with reasonable survival expectations, improves patient disease-free survival and can prevent potentially life-threatening complications, such as splenic rupture. 18F-FDG PET has very high sensitivity and specificity for differentiating benign and malignant splenic lesions especially in patients who are in the follow up protocol due to primary malignancy.

WFUMB Position Paper-Incidental Findings, How to Manage: Spleen

The World Federation for Ultrasound in Medicine and Biology (WFUMB) is addressing the issue of incidental findings (IFs) with a series of publications entitled "Incidental Imaging Findings-The Role of Medical Ultrasound." IFs are less commonly encountered in the spleen than in many other abdominal organs but remain a frequent dilemma in clinical practice. A histological diagnosis is rarely necessary for patient management. Many IFs, such as secondary spleens and splenic cysts, are harmless and do not require any further investigation. The diagnosis of many other focal splenic lesions is, however, often problematic. The following overview is intended to illustrate a variety of incidentally detected spleen pathologies such as size variants, shape variants, secondary spleens, focal splenic lesions and splenic calcifications. It should aid the examiner in establishing the diagnosis. Moreover, it should help the ultrasound practitioner decide which pathologies need no further investigation, those requiring interval imaging and cases in which immediate further diagnostic procedures are required.

Focal splenic lesions: Imaging spectrum of diseases on CT, MRI and PET/CT

The spleen can be affected by a variety of diseases. Some of them are readily identified as variations of normal or benign diseases on imaging. However, for a substantial number of focal splenic abnormalities, the diagnosis can be difficult so that histopathologic analysis may be required for a definite diagnosis. In this review, the typical splenic abnormalities that can be diagnosed with imaging with a high degree of confidence are illustrated. The complementary role of computed tomography (CT), magnetic resonance imaging and positron emission tomography/CT that helps make a diagnostic approach is discussed. Finally, current applications and future trends of radiomics and artificial intelligence for the diagnosis of splenic diseases are addressed.

Utility of Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Patients with Visceral Leishmaniasis: Case Report and Literature Review

The diagnosis of visceral leishmaniasis (VL) is complicated and often unsuspected. Little is known of the usefulness of nuclear imaging in VL. Our objective was to describe findings seen in fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in cases of VL. We retrospectively reviewed VL cases diagnosed at Vall d'Hebron University Hospital from May 2012 to May 2018 and selected those that had an FDG-PET/CT performed. Information on procedures and details of the FDG-PET/CT features and follow-up were collected. We then systematically reviewed the literature on VL and FDG-PET/CT. Four of 43 patients diagnosed with VL had an FDG-PET/CT performed. All four patients presented diffuse splenic uptake of FDG-PET/CT. Adenopathy was not always present, and bone marrow uptake was found in two patients. A posttreatment FDG-PET/CT in one patient revealed normalization of initial findings. In the literature review, 43 of 50 cases presented similar splenic uptake in the PET/CT, being described as different patterns: "increased metabolism," "homogeneous," "diffuse," "diffuse and multifocal," "nodular," "patchy and granular," "subcortical," and "compatible with lymphoma." Other frequent findings were bone marrow uptake and adenopathies. We, therefore, conclude that FDG-PET/CT could become a useful tool for the diagnosis and follow-up of VL and that VL should be taken into account in patients with fever of unknown origin with enhanced splenic uptake in FDG-PET/CT. Differential diagnosis in these cases should be made with splenic primary lymphoma, virus infections, chemotherapy, and colony-stimulating factor therapy. Further structured studies with more cases are needed to define its diagnostic and prognostic value.

Peripheral Photopenia on Whole-Body PET/CT Imaging With 18F-FDG in Patients With Compartment Syndrome and Mesenteric Venous Thrombosis

We present 2 cases that demonstrate photopenia in peripheral areas on whole-body PET/CT imaging with F-FDG as a sign of absent perfusion with severe short-term complications. The scan of the first patient shows photopenia in the right ankle and foot, resulting from compartment syndrome, caused by hemolytic group A streptococcus bacteremia with endocarditis and septic emboli, necessitating lower leg amputation. The scan of the second patient shows photopenia in the transverse colon, resulting from mesenteric venous thrombosis caused by polycythemia vera, leading to necrosis and perforation of the transverse colon, necessitating transverse and right hemicolectomy.

Splenectomy for Solitary Splenic Metastasis in Recurrent Papillary Thyroid Cancer. A Case Report and Literature Review

Thyroid cancer is the most common endocrine malignancy, presenting with 23 500 new cases per year in the United States. About 7-23% of the patients will present recurrent metastases disease during follow-up. The classic variant of papillary carcinoma is less aggressive compared to its other variants like diffuse sclerosing, tall cell or columnar cell, and insular variants, and the sites to which this metastasizes is already well identified. Metastasis to the spleen is an extremely rare manifestation of papillary thyroid cancer. To date, only 3 cases have been reported in the literature. Herein, we present a 52-year-old male, who developed spleen metastases, 2.4 years after total thyroidectomy and central neck dissection followed by radioactive iodine ablation and seven months after treatment with sorafenib for lung metastases. The splenic lesion was detected in surveillance studies. This case highlights that splenic metastasis, although rare, may occur even in a patient with a locoregional and systemic controlled thyroid cancer and that it can be treated safely with surgical resection.

[Gaucher Disease type 1 mimicking immune thrombocytopenia: Role of hyperferritinemia and hypergammaglobulinemia in the initial evaluation of an isolated thrombopenia]

INTRODUCTION

Gaucher disease type 1 is a rare genetic disease. It can cause thrombocytopenia. Current guidelines do not support bone marrow examination in front of isolated thrombocytopenia if no evidence suggests malignant hemopathy. This strategy aiming at sparing unnecessary investigations makes such rare diseases more difficult to diagnose.

CASE REPORT

A 31-year-old woman was diagnosed with immune thrombocytopenia according to current guidelines. She presented later with mild splenomegaly. Bone marrow aspirate smears showed Gaucher cells. Gaucher disease was then confirmed. Looking backward, initial biological clues (hyperferritinemia, hypergammaglobulinemia) should have enabled to consider the diagnosis.

CONCLUSION

Gaucher disease type 1 can be responsible for apparently isolated thrombocytopenia. The disease must be looked for if the thrombocytopenia is associated with unexplained hypergammaglobulinemia or hyperferritinemia. Diagnosing immune thrombocytopenia without bone marrow sample requires to systematically pay attention to any clinical or biological abnormality, not to ignore rare differential diagnoses.

Hamartoma of the spleen (splenoma) with calcifications in a child with beta-thalassemia: A case report

Splenic hamartoma (or splenoma) is a rare, benign, vascular tumor, often incidentally found at imaging, surgery or autopsy. Albeit usually asymptomatic and rare in children, when it occurs in the pediatric population it is more commonly symptomatic. We report a case of a 15-year-old girl with iron-deficiency anemia and beta-thalassemia, who had a large (10 × 8 × 7 cm) splenic lesion with calcifications, incidentally found during follow-up for splenomegaly and histologically characterized as hamartoma with calcified areas. The association of hamartoma and hematological disorders is a very unusual condition in children.

Splenic Angiosarcoma: A Diagnostic Splenectomy Finding

Splenic tumors are not frequent. Blood vessel neoplasms are a rare category of tumors and have an extremely low incidence in the spleen. This case report aims to describe a 57-year-old woman in whom a routine imaging examination had shown splenic cysts. During her follow-up, the cysts became larger and increased in number. A diagnostic splenectomy was performed and its analysis showed a rare splenic angiosarcoma.

The value of contrast-enhanced dynamic and diffusion-weighted MR imaging for distinguishing benign and malignant splenic masses

OBJECTIVE

To assess the value of contrast-enhanced dynamic and diffusion-weighted (DW) MR imaging for differentiating malignant from benign splenic lesions.

METHODS

This retrospective study included 51 patients with 35 benign and 16 malignant focal splenic lesions. All patients underwent contrast-enhanced dynamic and DW MR imaging. Two radiologists evaluated the MR images in consensus. Significant imaging findings on univariate and multivariate analyses were identified and their diagnostic performance for predicting the malignant splenic lesion was analyzed. Using receiver-operating characteristic analysis, the optimal cut-off of the apparent diffusion coefficient (ADC) value corresponding to the maximal Youden's index (J) for differentiating the two groups was determined.

RESULTS

In univariate analysis, low signal intensity (SI) on the arterial, portal and 3-min delayed-phase images, high or iso SI on the DW image, iso or low SI on the ADC map, the presence of diffusion restriction and arterial hypovascularity with a progressive enhancement pattern were more frequently observed (p < 0.05) in malignant splenic lesions. The ADC value was significantly lower for malignancy than for benignancy (0.78 ± 0.24 vs 1.16 ± 0.53 × 10(-3) mm(2) s(-1); p < 0.001). The optimal cut-off ADC value for differentiating the two groups was 0.995 × 10(-3) mm(2) s(-1). In multivariate analysis, findings that differentiated malignant from benign splenic lesions were low SI on the 3-min delayed-phase image [odds ratio (OR), 27.68; p = 0.006] and the presence of diffusion restriction (OR, 48.01; p = 0.002). When two of these criteria were combined, 12 (75.0%) of 16 malignant splenic masses were identified with a specificity of 100%.

CONCLUSION

Contrast-enhanced dynamic and DW MR imaging may be helpful for differentiating malignant from benign splenic lesions. A low SI on the 3-min delayed phase and diffusion restriction are the most reliable findings for the differentiation of malignant from benign splenic lesions.

ADVANCES IN KNOWLEDGE

Dynamic and DW MR imaging help in distinguishing malignant from benign splenic lesions. A low SI on the 3-min delayed phase and diffusion restriction are the most reliable findings for the differentiation of malignant from benign splenic lesions.

FDG PET/CT Findings in Multiple Splenic Amebomas (Amebic Granulomas)

Splenic ameboma (amebic granuloma) is rare. A 38-year-old man with a severe pneumonia due to inhalation of swimming pool water 18 months ago complained of night sweat, tiredness, and anorexia for 1 month. Abdominal ultrasound showed multiple nodules in the spleen. These nodules showed slight enhancement on enhanced CT and intense FDG uptake on PET/CT. Splenectomy was performed. Multiple splenic amebomas were confirmed by pathology. Free-living amoebae were also detected in samples of pleural effusion and blood. Splenic ameboma, although rare, should be included in the differential diagnosis with isolated focally increased FDG activity in the spleen.

Enhanced CT and FDG PET/CT findings of splenic hamartoma

Splenic hamartomas are very rare benign vascular tumors. A 67-year-old man was referred after an incidental detection of a splenic lesion. Abdominal-enhanced CT showed a splenic lesion with progressive enhancement. This lesion showed intense FDG uptake with an SUVmax of 9.2. The patient underwent splenectomy. Splenic hamartoma was confirmed by pathologic evaluation. In this tumor, the disorganized splenic sinus contained a large amount of lymphocytes and plasma cells, which may contribute to the intense FDG uptake. This case indicates that splenic hamartoma should be included in the differential diagnosis of focal FDG accumulation along with tumor and nontumor conditions.

Splenic metastasis from gastric adenocarcinoma: A rare case

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We present a case of a 71-year-old patient with isolated splenic metastasis, diagnosed 6 years after primary treatment of a gastric adenocarcinoma, who underwent splenectomy.

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Isolated splenic metastasis, particularly from gastric adenocarcinoma, are rare.

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In cases of isolated splenic metastasis from gastric adenocarcinoma, fit patients should be considered for splenectomy, since there are reports of good patient survivals.

INTRODUCTION

Isolated splenic metastasis are very rare. There are only a few reported cases of patients with isolated splenic metastasis from gastric primary tumors.

PRESENTATION OF CASE

We present a case of a 71-year-old patient with isolated splenic metastasis, diagnosed 6 years after primary treatment of a gastric adenocarcinoma, who previously had a lung resection also for metastasis. The patient was submitted to chemotherapy and then to splenectomy. The patient is alive and has no evidence of disease 7 months after splenectomy.

DISCUSSION

We discuss the theories that explain the rare event of splenic metastasis, the route of metastization, the workup, treatment and survival of patients with isolated splenic metastasis. To the best of our knowledge, our case has the second longest interval from the primary diagnosis of gastric cancer to the diagnosis of splenic metastasis.

CONCLUSION

In cases of isolated splenic metastasis from gastric adenocarcinoma, fit patients should be considered for splenectomy, since there are reports of good patient survivals.

Isolated splenic metastasis of ovaric cancer. Case report and literature review

Splenic metastasis is extremely rare and are usually found in conjunction with metastasis of other organs. In addition, late recurrence even after 10 years of operation is very unusual. The most common sources of splenic metastasis are lung, colonrectal, melanoma, breast and ovarian carcinoma. We present a case of 67 year old woman who was admitted to our department with a solitary splenic metastases after hysterectomy with bilateral salpingo-oophorectomy for ovaric carcinoma 10 years ago. In conclusion, solitary splenic metastasis are very rare and the incidence of the reported cases in the medical literature is increasing. The treatment of choice is laparoscopic splenectomy that must be followed by chemotherapy in order to prevent the development of other possible micrometastases.

Rare case of isolated splenic metastases from gastric cancer detected with fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography

We report a rare case of isolated splenic metastasis from gastric cancer detected with fluorine-18 fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT). A 55-year-old man with gastric cancer 1 year post surgery, evaluated with PET/CT showed focal, intense uptake in the spleen, with no other abnormal findings. On splenectomy, the lesion was confirmed as metastasis from gastric cancer pathologically.

Imaging-guided biopsy of (18)F-FDG-avid extrapulmonary lesions: do lesion location and morphologic features on CT affect the positive predictive value for malignancy?

OBJECTIVE

The purpose of our study was to analyze the effect of lesion location and morphologic appearance on CT on the positive predictive value (PPV) for malignancy of all extrapulmonary lesions that were (18)F-FDG avid on PET/CT and that were biopsied under imaging guidance.

MATERIALS AND METHODS

Between January 2004 and December 2010, 227 patients underwent imaging-guided biopsy of 231 PET-positive extrapulmonary lesions with diagnostic pathologic results. The PET PPV for malignancy was retrospectively calculated and stratified according to lesion location and morphologic appearance.

RESULTS

The overall PET PPV for malignancy was 72%. Inflammatory processes accounted for the majority of benign biopsy results. Lesion location significantly affected the PPV (p < 0.001). Bone (96%) and liver (90%) lesions had significantly higher PPVs for malignancy compared with other locations, whereas lymph nodes (60%) had a significantly lower PPV for malignancy. Lesions that were morphologically suspicious and morphologically benign according to CT findings alone were associated with PPVs of 74% and 57%, respectively (p = 0.05). FDG-avid subcentimeter lymph nodes (n = 8) had a PPV for malignancy of 38%.

CONCLUSION

Over half of PET-avid morphologically benign-appearing lesions and one third of PET-avid subcentimeter lymph nodes were found to be malignant at biopsy, suggesting that benign morphologic appearance alone should not preclude further workup of a PET-positive lesion. Biopsies of FDG-avid lesions in liver and bone yielded high rates of true malignancy, whereas biopsies of lymph nodes yielded a lower rate of malignancy compared with other lesion locations.

Isolated splenic metastases from gastric carcinoma: A case report and literature review

Isolated metastases to the spleen from gastric carcinoma is very rare. Only a few cases have been reported in the literature. We herein present a case of isolated splenic metastases in a 62-year-old man, occurring 12 mo after total gastrectomy for gastric carcinoma. The patient underwent a laparoscopic exploration, during which two lesions were found at the upper pole of the spleen, without involvement of other organs. A laparoscopic splenectomy was performed. Histological examination confirmed that the splenic tumor was a poorly differentiated adenocarcinoma similar to the primary gastric lesion. The postoperative course was uneventful and the patient has been well for 9 mo, with no tumor recurrence. The clinical data of 18 cases of isolated splenic metastases from gastric carcinoma treated by splenectomy were summarized after a literature review. To our knowledge, this is the first reported case of isolated splenic metastases undergoing laparoscopic splenectomy.

Adrenal imaging

OBJECTIVE

Adrenal nodules are frequently encountered on current high-resolution imaging, and accurate characterization of such lesions is critical for appropriate patient care. Our article highlights how imaging techniques such as CT densitometry, CT washout characteristics, chemical shift MRI, PET, and PET/CT help characterize most adrenal lesions. We focus on these techniques as well as specifically, because of space constraints, the varied imaging appearances of adrenocortical carcinoma, pheochromocytoma, and lymphoma on these techniques.

CONCLUSION

The imaging characterization of adrenal lesions has continued to advance over the past decade as new technologies have evolved. CT, MRI, PET, and PET/CT are now established clinical techniques capable of differentiating benign from malignant adrenal lesions.

Splenic hamartoma in a child in the era of PET-CT

We present a case of a healthy 7-year-old female with an incidental finding of a growing splenic lesion, diagnosed as a splenic hamartoma after splenectomy. This case highlights the diagnostic challenge of splenic lesions and that the role of positron emission tomography/computerized tomography (PET/CT) in defining splenic lesions in the pediatric population remains to be defined.

PET/CT for the characterization of adrenal masses in patients with cancer: qualitative versus quantitative accuracy in 150 consecutive patients

OBJECTIVE

The objective of our study was to evaluate a large cohort of patients with PET/CT to determine whether qualitative (visual) assessment, quantitative standardized uptake value (SUV), or standardized uptake ratio (SUR) techniques should be used when attempting to characterize adrenal masses in patients with cancer.

MATERIALS AND METHODS

The study group was composed of 150 consecutive patients (78 men, 72 women; mean age, 60 years; range, 24-88 years) with documented adrenal lesions. All patients were known to have an underlying primary malignancy and were referred for PET/CT to evaluate the underlying primary and metastatic tumor burden. Definitive lesion characterization was determined by evaluating all histologic adrenal specimens and all relevant prior and follow-up CT scans, including unenhanced, contrast-enhanced, and delayed contrast-enhanced washout studies.

RESULTS

Of the 139 benign lesions, 109 were considered benign by CT densitometry measurements and 135 by qualitative PET data. Qualitative PET characterized 28 of 30 benign lesions that were considered indeterminate by unenhanced CT. All 26 malignant lesions were characterized by PET: All showed qualitative and quantitative signal intensity greater than the liver. By combining unenhanced and qualitative CT data with the retrospective PET data, the analysis yielded a sensitivity of 100% for the detection of malignancy, a specificity of 99%, a positive predictive value (PPV) of 93%, a negative predictive value (NPV) of 100%, and an accuracy of 99% (Table 1). Conversely, for the detection of benignity, the sensitivity, specificity, PPV, NPV, and accuracy were 99%, 100%, 100%, 93%, and 99%, respectively.

CONCLUSION

PET/CT is a highly accurate method for differentiating benign from malignant adrenal masses particularly when using qualitative, rather than quantitative, PET data. The routine use of quantitative mean or maximal SUV or SUR data may be unnecessary. Occasional benign lesions do show mild to moderate increased FDG uptake compared with that of the liver and may mimic some malignant lesions. Without evidence that these lesions are benign by unenhanced CT densitometry or adrenal mass stability or growth from previous CT scans, we recommend that these lesions be characterized using contrast-enhanced washout tests and that if those tests are inconclusive, using percutaneous biopsy if early lesion characterization is mandatory.

Adrenal nodules at FDG PET/CT in patients known to have or suspected of having lung cancer: a proposal for an efficient diagnostic algorithm

PURPOSE

To develop an algorithm to maximize the diagnostic yield of positron emission tomography (PET)/computed tomography (CT) by using defined attenuation and standardized uptake value (SUV) criteria.

MATERIALS AND METHODS

An IRB-approved, HIPAA-compliant retrospective review with waiver of informed consent of data in 1388 consecutive patients who underwent PET/CT for known or suspected lung cancer was completed, and 187 adrenal nodules were identified in 147 patients. Nodules were defined histologically or by size change (malignant, n = 37) or stability for more than 1 year (benign, n = 58). Nodules not sampled for biopsy and with less than 1 year of follow-up were considered indeterminate (n = 92). Diameter, mean attenuation, SUV(max), and SUV ratio (nodule SUV(max)/liver SUV(avg)) were compared with t test and receiver operating characteristic analyses. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for diameter > 3 cm, mean attenuation > 10 HU, nodule SUV(max) > 3.1, and SUV ratio > 1.0. These were also calculated for higher SUV(max) and SUV ratio thresholds that were found to exclude all false-positives. Diagnostic accuracy was compared by using the McNemar test (P < .05).

RESULTS

In the study group of 147 patients (aged 42-88 years; mean, 65.5 years; 59 women), combined PET/CT with mean attenuation > 10 HU and SUV(max) > 3.1 had 97.3% sensitivity and 86.2% specificity. Combined PET/CT with mean attenuation > 10 HU and SUV ratio > 1.0 had 97.3% sensitivity and 74.1% specificity. The accuracies of these threshold combinations (90.5% and 83.2%, respectively) were significantly different (P = .008). Applying a further cutoff of SUV ratio > 2.5 enabled identification of 22 of 37 metastatic lesions and exclusion of all fluorodeoxyglucose-avid benign nodules.

CONCLUSION

Definitive identification of many metastases can be accomplished by applying an SUV ratio cutoff of greater than 2.5, allowing pragmatic management of adrenal nodules that initially test positive with the combined PET/CT criteria SUV(max) > 3.1 and mean attenuation > 10 HU.

SUPPLEMENTAL MATERIAL

http://radiology.rsnajnls.org/cgi/content/full/250/2/523/DC1.

Imaging features of primary extranodal lymphomas

Lymphomas are generally considered tumours of lymph nodes, but up to 40% arise extranodally. This group shows distinctive pathological, radiological, and clinical features. Different subtypes of extranodal lymphoma may show sufficiently specific radiological features to be of significant value in both establishing a diagnosis of lymphoma and ascertaining the exact subtype. Rapidly evolving lymphoma classifications and emergence of new entities have, however, hampered the accurate description of these features in the literature. In this review, we discuss the radiological appearances, using a variety of imaging methods, of the full spectrum of primary extranodal lymphomas, categorized according to the current World Health Organisation classification.

Incidental adrenal lesions: principles, techniques, and algorithms for imaging characterization

Incidental adrenal lesions are commonly detected at computed tomography, and lesion characterization is critical, particularly in the oncologic patient. Imaging tests have been developed that can accurately differentiate these lesions by using a variety of principles and techniques, and each is discussed in turn. An imaging algorithm is provided to guide radiologists toward the appropriate test to make the correct diagnosis.

Utility of PET/CT in differentiating benign from malignant adrenal nodules in patients with cancer

OBJECTIVE

The purpose of this retrospective study was to determine the sensitivity and specificity of combined PET/CT in differentiating benign from malignant adrenal nodules measuring at least 1 cm in diameter in patients with cancer.

MATERIALS AND METHODS

We reviewed the radiology reports and images of patients with known malignant disease who had undergone PET/CT for cancer staging or surveillance and who had adrenal nodules at least 1 cm in diameter. We identified 112 adrenal nodules in 96 patients. Two-dimensional PET had been performed 1 hour after administration of (18)F-FDG. Unenhanced CT was performed for attenuation correction, to determine lesion size, and for coregistration with PET data. Adrenal nodules were considered to have a positive PET result if the average standardized uptake value was greater than that of the liver. Follow-up data and biopsy reports were used to determine the pathologic status of the adrenal nodules.

RESULTS

Thirty adrenal lesions were malignant. Twenty-five of the 30 malignant nodules had positive PET results. Twelve of 82 benign nodules were PET positive with a sensitivity of 83.3% and specificity of 85.4%. Patients with four of five malignant nodules with negative PET results had received previous therapy. The positive predictive value for detection of malignant lesions was 67%, and the negative predictive value was 93%.

CONCLUSION

Adrenal masses that are not FDG avid are likely to be benign with a high negative predictive value. Especially in patients undergoing therapy, however, there is a small but statistically significant false-negative rate. A considerable proportion of benign nodules have increased FDG activity.