PET imaging of cerebral and pulmonary Nocardia infection

We report the case of a 69-year-old man who was suspected to have lung cancer with a single metastasis to the brain. Initial workup for neurologic and pulmonary symptoms demonstrated a ring-enhancing lesion in his right frontal lobe on MRI and a lung mass on CT. An F-18 fluorodeoxyglucose positron emission tomography (FDG PET) scan demonstrated marked glucose hypermetabolism in the lung and brain lesions with maximal standard uptake values (SUV) in both lesions of approximately 11. Biopsy of the brain mass revealed an abscess and cultures grew Nocardia. He was treated for nocardiosis, and a repeat CT of the chest in 2 months and MRI of the brain in 5 months showed nearly complete resolution of the lesions. Currently, there are few reported cases of PET evaluation of brain abscesses, particularly Nocardia. We discuss the appearance of brain infections on FDG PET scans in immunocompetent and immunocompromised patients.     

FDG–PET imaging findings of a pulmonary sclerosing hemangioma

Pulmonary sclerosing hemangiomas are generally regarded as benign lung lesions arising from type II pneumocytes and bronchial epithelium. In some cases malignant features may be present. There are several case reports describing the radiographic, computed tomography (CT), and magnetic resonance imaging (MRI) characteristics of pulmonary sclerosing hemangiomas. Given the potential for low-grade malignancy 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging may be useful in the diagnostic work up and therapeutic planning in these patients, however the FDG–PET imaging features of pulmonary sclerosing hemangiomas are not well defined. We report a case of histopathologically diagnosed sclerosing hemangioma of the lung which demonstrated intermediate uptake of FDG on the preoperative PET/CT evaluation.     

Positron emission tomography of incidentally detected small pulmonary nodules

The aim of this study was to assess the value of fluorodeoxyglucose positron emission tomography (FDG PET) imaging of small pulmonary nodules incidentally detected by spiral computed tomography (CT) in a high-risk population. Ten patients (five females, five males, aged 54-72 years) were recruited from an ongoing 4-year placebo controlled intervention study of the effect of inhaled steroids in 300 smokers with moderate to severe chronic obstructive pulmonary disease. The participants received yearly CT scans of the chest. Patients with a negative chest radiograph at the time of inclusion, but with pulmonary nodules indeterminate for malignancy detected by conventional spiral CT on a subsequent scan, were referred for FDG PET. Histological diagnoses were sought for all nodules with FDG uptake or where CT showed that they had grown. Ten patients had pulmonary nodules indeterminate for malignancy (approx. 3.3% of the entire study population). The prevalence of malignancy in this group was 50%. The accuracy of PET was high, in spite of the fact that seven patients had nodules smaller than 15 mm and two patients had bronchoalveolar cell carcinoma. This small prospective study indicates that subsequent assessment with FDG PET of small pulmonary nodules incidentally detected by CT has the potential to minimize the numbers of invasive procedures performed in individuals with a benign pulmonary lesion. FDG PET also increases the possibility of an early diagnosis as compared to the strategy of watchful waiting.     

Efficiency of 18F-FDG and 99mTc-depreotide SPECT in the diagnosis of malignancy of solitary pulmonary nodules

Purpose The purpose of the study was to compare ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and ^99mTc-depreotide single-photon emission computed tomography (SPECT) in the diagnosis of malignancy of solitary pulmonary nodules (SPNs).Methods Twenty-eight patients without any history of cancer and presenting an SPN (0.8–3 cm in size) underwent FDG PET and depreotide SPECT. Depreotide SPECT and FDG PET were performed on a double-head gamma camera and a dedicated PET scanner respectively. Twenty-five out of 28 lesions were removed by thoracotomy or assessed by biopsy (n=1) and histologically examined. A strategy of serial CT scanning was adopted in the three remaining patients.Results Histological findings revealed 18 malignant nodules and seven benign lesions. Stability over a 2-year period indicated a benign process in the remaining three cases. Both techniques yielded true positive results in 15 of the 18 cancers. FDG PET identified two additional adenocarcinomas not detected by depreotide SPECT. A carcinoid tumour not visualised on FDG PET was identified by depreotide SPECT. Seven of the ten benign lesions did not reveal tracer uptake on either depreotide SPECT or FDG PET. Both techniques showed false positive results for the same two lesions. One more false positive was seen on FDG PET. FDG PET and depreotide SPECT had a sensitivity of 94.4% and 88.9% respectively; this difference was not significant. In our experience, depreotide SPECT and FDG PET are equally sensitive (92.3%) for large (>1.5 cm) and equally specific (85.7%) for small (up to 1.5 cm) SPNs suspicious for malignancy.Conclusion This study showed ¹⁸F-FDG PET to be more sensitive than ^99mTc-depreotide SPECT in the diagnosis of malignancy of SPNs. However, the combination of both techniques may provide additional accuracy.     

Lymphadenopathy by Scrub Typhus Mimicking Metastasis on FDG PET/CT in a Patient with a History of Breast Cancer

We report the case of a 60-year-old woman with left-sided breast cancer who showed lymphadenopathy mimicking metastatic lesions. She underwent surveillance ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) after treatment. PET/CT demonstrated multiple lymphadenopathies with increased FDG uptake, most notably in the right axilla. She had an eschar on the right axillary area, and her serologic test was positive for anti-Orientia tsutsugamushi IgM antibody. Ten months after the treatment, follow-up FDG PET/CT and ultrasonography showed improvement in generalized lymphadenopathy.     

Incidentally Detected Small Intestine Intussusception Caused by Primary Small Intestine Carcinoma on <Superscript>18</Superscript>F-FDG PET/CT

Small intestine intussusception in adults is a rare condition mainly caused by primary or metastatic small intestine malignancy. Here, we present a 72-year-old male patient who was diagnosed with small intestine cancer that was presented as small intestine intussusception on hybrid ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT). The patient was initially referred for an abnormality on a chest radiography and severe anemia. FDG PET/CT showed the lung lesion in the right upper lobe of lung as a high FDG uptake mass. Accidentally, FDG PET demonstrated another intense hypermetabolic intraluminal lesion in the small intestine accompanied with intussusception shown as a circumferential hypermetabolic wall. By pathologic examination, the patient was diagnosed as primary small intestine cancer with lung metastasis. This case highlights usefulness of hybrid FDG PET/CT to identify unexpected malignancy.     

FDG avid pulmonary amyloid nodule in a patient with metastatic renal cell cancer on 18F-FDG PET/CT

A 60-year-old man with a background of resected clear cell renal cancer and resected colorectal adenocarcinoma presented with a pulmonary mass lesion in the left upper lobe which was avid on 18-F FDG PET/CT. Needle biopsy confirmed metastatic renal cell cancer, which was surgically excised with wedge resection. Follow-up imaging 6 months later demonstrated a second slowly enlarging subcentimeter nodule in the contralateral lung with increasing FDG avidity, suspicious of further small volume oligometastatic disease. Following surgical resection of the second pulmonary lesion, histopathological examination demonstrated nodular pulmonary amyloidosis and no evidence of malignancy.     

F-18 fluorodeoxyglucose positron emission tomography in pulmonary cryptococcoma

Cryptococcosis is not uncommon. Potential interpretation pitfalls should be kept in mind when fluorodeoxyglucose (FDG) positron emission tomography (PET) is used for differentiating pulmonary nodules and for discriminating infection from malignancy, especially in areas where the prevalence of granulomatous infection is high and in immunocompromised patients. In this case, a nodular mass was shown on chest radiography and computed tomographic (CT) scanning. A consolidated infection or a bronchioloalveolar carcinoma was suspected because the CT scan showed air bronchograms within the mass and another perihilar infiltration. The FDG PET scan clearly delineated the lesion and had intermediately high glucose uptake (standard uptake value, 3.8-4.0), which led to the exclusion of the possibility of bronchioloalveolar carcinoma because most of these tumors had normal or mildly increased FDG accumulation. Cryptococcoma was finally diagnosed. Hence, the CT scan and FDG PET played complementary roles in the differential diagnosis of this nodular mass.     

Occult lung infarction may induce false interpretation of 18F-FDG PET in primary staging of pulmonary malignancies

Purpose The aim of the present report is to describe abnormal ¹⁸F-fluorodeoxyglucose (FDG) accumulation patterns in the pleura and lung parenchyma in a group of lung cancer patients in whom lung infarction was present at the time of positron emission tomography (PET).Methods Between November 2002 and December 2003, a total of 145 patients (102 males, 43 females; age range 38–85 years) were subjected to whole-body FDG PET for initial staging (n=117) or restaging (n=11) of lung cancer or for evaluation of solitary pulmonary nodules (n=17). Of these patients, 24 displayed abnormal FDG accumulation in the lung parenchyma that was not consistent with the primary lesion under investigation (ipsilateral n=12, contralateral n=9 or bilateral n=3). Without correlative imaging, this additional FDG uptake would have been considered indeterminate in differential diagnosis.Results Of the 24 patients who were identified as having such lesions, six harboured secondary tumour nodules diagnosed as metastases, while in three the diagnosis of a synchronous second primary lung tumour was established. Additionally, nine patients were identified as having post-stenotic pneumonia and/or atelectasis (n=6) or granulomatous lung disease (n=3). In the remaining six (4% of all patients), a diagnosis of recent pulmonary embolism that topographically matched the additional FDG accumulation (SUV_max range 1.4–8.6, mean 3.9) was made. Four of these six patients were known to have pulmonary embolism, and hence false positive interpretation was avoided by correlating the PET findings with those of the pre-existing diagnostic work-up. The remaining two patients were harbouring small occult infarctions that mimicked satellite nodules in the lung periphery. Based on histopathological results, the abnormal FDG accumulation in these two patients was attributed to the inflammatory reaction and tissue repair associated with the pathological cascade of pulmonary embolism.Conclusion In patients with pulmonary malignancies, synchronous lung infarction may induce pathological FDG accumulation that can mimic active tumour manifestations. Identifying this potential pitfall may allow avoidance of false positive FDG PET interpretation.     

Widespread metastases from sarcomatoid renal cell carcinoma detected by 18F-FDG positron emission tomography/computed tomography

We present a case of sarcomatoid renal cell carcinoma (RCC). Although preoperative computed tomography (CT) scans demonstrated small lung and pleural nodules and mediastinal lymphadenopathy, these findings were not conclusive for metastases. Whole-body fluorine-18 fluorodeoxyglucose positron emission tomography and CT (FDG-PET/CT) performed 15 days after right nephrectomy showed intense FDG uptake in the aforementioned lesions (lung and pleural nodules, mediastinal lymph nodes). Unexpectedly, focal increased FDG uptake was found in the right infraspinatus muscle. FDG-PET/CT was considered useful for evaluating distant metastases and thus portending the aggressive nature of sarcomatoid RCC.     

Bilateral Tubo-Ovarian Abscess Mimics Ovarian Cancer on MRI and 18F-FDG PET/CT

A 20-year-old woman, who presented with a several-week history of abdominal pain, was referred for magnetic resonance imaging (MRI) and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) after an ultrasound showed complex cystic masses arising from both ovaries. The MRI and ¹⁸F-FDG PET/CT imaging characteristics of the ovarian masses were strongly suspicious for malignancy, and the masses were surgically removed. Histopathological evaluation revealed a bilateral tubo-ovarian abscess, with no evidence of malignancy. This case highlights a potentially serious pitfall in the evaluation of suspicious pelvic masses by ¹⁸F-FDG PET/CT, whereby a complex bilateral tubo-ovarian abscess may mimic the PET/CT imaging characteristics of an ovarian or pelvic malignancy.     

Uterine Intravenous Leiomyomatosis with Intracardiac Extension and Pulmonary Benign Metastases on FDG PET/CT: A Case Report

A 48-year-old woman presented with a 50-day history of irregular vaginal bleeding and lower abdominal pain. Ultrasound indicated an extremely large occupying lesion in the pelvic cavity that was highly suggestive of malignancy. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) was performed to further assess the nature of pelvic abnormality. PET/CT images demonstrated a diffusely lobulated mass ranging from cervix up to the inferior pole of kidneys with mild FDG uptake. Simultaneously, multiple nodules in bilateral lungs and a hypodense lesion in the right ventricle were shown without FDG-avidity. Based on the imaging results, the presumptive diagnosis was uterine intravenous leiomyomatosis with intracardiac extension and pulmonary benign metastases, which was subsequently confirmed by MRI and the lesion biopsy.     

Primary Renal Leiomyosarcoma Presenting with Subcutaneous and Osseous Metastases: Staging and Follow-Up with 18F-FDG PET/CT

A 60 year old woman who presented with multiple small subcutaneous nodules in the upper back and arms, was referred for an [18F] fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) after histological evaluation revealed metastatic leiomyosarcoma of unknown origin. The PET/CT showed multiple ¹⁸F-FDG-avid subcutaneous nodules, bone lesions, as well as a large left renal mass, which was biopsied to confirm a primary renal leiomyosarcoma arising from the renal parenchyma. A post therapy PET/CT showed overall progression of disease. The use of ¹⁸F-FDG PET/CT in the staging and evaluation of response to therapy of a renal leiomyosarcoma has not been previously described in the literature.     

Value of whole-body FDG PET in management of lung cancer

18F-fluorodeoxyglucose (FDG) PET imaging provides physiologic and metabolic information that characterizes lesions that are indeterminate by CT. FDG PET imaging is sensitive to the detection of lung cancer in patients who have indeterminate lesions on CT, whereas low grade malignancy such as bronchioloalveolar carcinoma and carcinoid may be negative on FDG PET. The specificity of PET imaging is less than its sensitivity because some inflammatory processes, such as active granulomatous infections, avidly accumulate FDG. This possibility should be kept in mind in the analysis of PET studies of glucose metabolism aimed at differentiating malignant from benign solitary pulmonary nodules. FDG uptake is considered to be a good marker of cell differentiation, proliferative potential, aggressiveness, and the grade of malignancy in patients with lung cancer. FDG PET accurately stages the distribution of lung cancer. Several studies have documented the increased accuracy of PET compared with CT in the evaluation of the hilar and mediastinal lymphnode status in patients with lung cancer. Whole-body PET studies detect metastatic disease that is unsuspected by conventional imaging. Management changes have been reported in up to 41% of patients on the basis of the results of whole-body studies. Whole-body FDG PET is also useful for the detection of recurrence. Several studies have indicated that the degree of FDG uptake in primary lung cancer can be used as an independent prognostic factor. Thus, whole-body FDG PET is clinically very useful in the management of lung cancer.     

Incidental Detection of Peri-Renal Hemorrhage on F-18 FDG PET/CT Imaging in a Patient with Polycystic Kidney Disease

A 72-year-old male patient with a history of polycystic kidney disease and lung malignancy underwent F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) for the evaluation of tumor recurrence. The FDG PET/CT and subsequent non-enhanced CT scans revealed a hemorrhage in the peri-renal space of the left original kidney. Interesting in this case was the incidental detection of unexpected peri-renal hemorrhage during an oncologic assessment with FDG PET/CT.     

<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.

     

Multiple muscle metastases from lung cancer detected by FDG PET/CT

A 71-year-old man with right lung mass, who was recently diagnosed histopathologically with pulmonary adenocarcinoma, was referred for staging of the primary tumor. Whole-body F-18 fluorodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT) demonstrated multiple hypermetabolic foci in various skeletal muscle localizations, suggesting extensive metastatic muscle involvements in addition to increased FDG uptake in the primary tumor. Subsequent biopsy and histopathological study confirmed muscle metastasis from lung adenocarcinoma. Skeletal muscle metastasis from lung cancer is rare, but multiple muscle metastases are even more unusual. FDG PET/CT is able to detect unexpected metastatic involvements such as multiple muscle metastases in lung cancer patients.     

Comparison of whole lung tomography and computed tomography for detecting pulmonary nodules.

Detecting pulmonary metastasis is important when planning surgical therapy, radiotherapy, or chemotherapy in patients with known malignancy. A series of 91 patients was studied by both whole lung tomography and computed tomography (CT) of the lungs. More pulmonary nodules were detected with CT than with whole lung tomography in 32 (35%) of the patients. Of the 91 patients in the study, 31 had resection of some or all of the pulmonary nodules. In 27 patients, the nodules were primary or metastatic malignant lesions. Bilateral pulmonary nodules were detected with CT in 13 patients when whole lung tomography had demonstrated nodules in only one lung. CT has replaced whole lung tomography as the method preferred by the authors for detecting pulmonary nodules in selected patients at risk to develop pulmonary metastasis.     

The clinical usefulness of F-18 FDG coincidence PET without attenuation correction and without whole-body scanning mode in pulmonary lesions comparison with CT, MRI, and clinical findings

PURPOSE: This study was undertaken to assess the clinical usefulness of fluorine-18 flurodeoxyglucose (F-18 FDG) coincidence detection (CoDe) positron emission tomography (PET) of various lung lesions by comparing it with CT, MRI, and clinical findings. MATERIALS AND METHODS: Forty-two patients with pulmonary lesions underwent CoDe PET using a dual-head gamma camera equipped with a 5/8 inch thick NaI (Tl) crystals. The patients were prepared for the study by overnight fasting. Data was acquired at approximately 1 hour after the intravenous injection of 111 to 370 MBq (3 to 10 mCi) of F-18 FDG. A spinal scan of the thorax was performed using a slip ring gantry for 30 minutes. After rebinning, routine tomographic slices were reconstructed without attenuation correction and the images were analyzed visually. RESULTS: Pathologic diagnoses and staging were obtained at surgery in nine patients; in the remaining 33 patients, aspiration cytology was available. CoDe PET detected all 35 pathologically proved malignant lesions. In nine patients who underwent surgery, seven CoDe PET studies corresponded with pathologic staging, whereas in six of the nine patients, CT and MRI corresponded with the pathologic findings. Seven patients also had benign lesions that showed FDG uptake. CONCLUSIONS: F-18 FDG CoDe PET was sensitive in the evaluation of lung lesions but was not specific for malignancy. F-18 FDG CoDe PET was more sensitive than CT and MRI in nodal staging in the limited number of patients studied thus far.     

肺黏膜相关淋巴组织型淋巴瘤的影像表现

目的 探讨肺黏膜相关淋巴组织型(MALT)淋巴瘤CT或18F-脱氧葡萄糖(FDG)PETCT表现及其诊断价值.方法 回顾性分析14例经手术及病理证实的肺MALT淋巴瘤的CT或18F-FDG PET-CT表现特点.结果 单肺病灶7例,双肺病灶7例,其中单发实变影3例,单发肿块影3例,单发结节影1例,多发结节影1例,肿块影合并结节影、斑片状影1例,实变影合并斑片状影4例,弥漫性间质性病变1例.9例有支气管充气征,5例有CT血管造影征.2例FDG代谢不均匀增高,最大标准摄取值超过2.5.结论 肺MALT淋巴瘤的影像特征性表现主要为单发或多发结节、肿块或实变影,内有支气管充气征,18F-FDG高代谢,确诊主要依靠病理组织学和免疫组织化学.

Abstract：

Objective To assess the value of CT or PET-CT with fluorine-18-labeled fluorodeoxyglucose (FDG) for the diagnosis of pulmonary mucosa-associated lymphoid tissue (MALT) type lymphoma. Methods The CT or FDG PET-CT findings in 14 patients with pathologically proved pulmonary MALT lymphoma were retrospectively analyzed. Results Lung lesions were unilateral in 7 patients and bilateral in 7 patients. Lesions presented as a single mass in 3 patients, as a single consolidation in 3 patients, as a nodule in 1 patient, as multiple nodules in 1 patient, as multiple patchy consolidations in 4 patients, as a mass with multiple nodules and patchy consolidations in 1 patients, as diffuse interstitial change in 1 patients. Air bronchogram was found in 9 patients and CT angiogram sign in 5 patients. On PET-CT, lesions showed heterogeneous FDG uptake in 2 patients, maximum standard uptake value was higher than 2. 5. Conclusion Imaging characteristics of pulmonary MALT lymphoma are single or multiple nodules or consolidations with air bronchogram on CT, and heterogeneous high FDG uptake on PET-CT.