Fanglan Li

Rectus Abdominis Muscle Metastasis From Papillary Thyroid Cancer Identified by I-131 Spect/ct

The major sites of distant metastases of differentiated thyroid cancer are cervical lymph nodes, lungs and bones and the minor sites include the brain, liver, kidney, skin, pleura, and muscle. Skeletal muscle, especially a rectus abdominis muscle metastasis from thyroid cancer, is extremely rare. In this report, a 53-year-old man with papillary thyroid cancer was treated with I-131 for the ablation of a postsurgical thyroid remnant. An incidental focus of abnormally increased I-131 uptake in the left abdomen was observed on a I-131 whole-body scan. Subsequent single photon emission computed tomography/computed tomography (SPECT/CT) scan showed the focus was located in the left rectus abdominis muscle. The lesion was surgically removed and pathologically confirmed as a metastasis.

Lung sequestration and Pott disease masquerading as primary lung cancer with bone metastases on FDG PET/CT.

The chest x-ray from a 37-year-old man with a history of back pain showed a mass in the left lower lung, which prompted an FDG PET/CT study to evaluate the nature of the mass and possible metastases. The images revealed peripherally increased FDG activity in the left lower lung mass. In addition, there was intense FDG activity in 2 adjacent thoracic vertebrae on PET images corresponding to the regions of bone destruction on the concurrent CT. Therefore, a possible diagnosis of lung carcinoma with bone metastases was suggested. However, subsequent tests demonstrated that the left lung mass was in fact a lung sequestration, whereas the spinal lesions were due to Pott disease (tuberculous spondylitis).

Hybrid SPECT/CT for attenuation correction of stress myocardial perfusion imaging.

Background: This study aimed to determine whether attenuation correction using the Hybrid SPECT/CT reduced attenuation artifacts. Methods and Results: Ninety-nine patients (55 men and 44 women) underwent coronary angiography and electrocardiography gated stress/rest myocardial perfusion imaging using Tc-99m sestamibi (MIBI) with CT-attenuation correction (CT-AC) for stress scans. Visual semi-quantitative analysis of the CT-AC and noncorrected perfusion images was performed. In this study, there was 39.3% moderate or severe misregistration. The overall specificity, sensitivity, and accuracy for noncorrected versus CT-AC were 62.9% versus 79.0% (P = 0.041), 94.6% versus 91.9% (P = NS), and 74.7% versus 83.8% (P = 0.035), respectively. CT-AC increased specificity in the right coronary artery region, from 77.9% to 98.7% (P = 0.000), accompanied by a decrease in specificity in the left anterior descending region, from 94.1% to 82.4% (P = 0.008). CT-AC significantly reduced defect scores in the inferior wall. This was more obvious in men than in women (P = 0.027). In the anterior wall, although a tendency for defect scores to increase with CT-AC was observed only in men, no significant difference was found between the gender (P = 0.049). Conclusion: Attenuation correction using Hybrid SPECT/CT improved specificity in the right coronary artery, but decreased specificity in the left anterior descending. This technique is likely to be more useful in men than in women.

Computed tomography attenuation correction improves the risk stratification accuracy of myocardial perfusion imaging.

PurposeComputed tomography attenuation correction (CT-AC) may improve the image quality and diagnostic accuracy of myocardial perfusion imaging. We evaluated the prognostic value of single-photon emission computed tomography (SPECT) myocardial perfusion imaging with CT-AC. MethodsTechnetium-99m sestamibi stress/rest myocardial perfusion imaging was performed with SPECT and CT-AC in 935 patients. Images without and with AC were rated using the summed stress score (SSS) and classified as normal (SSS, 0–3), mildly abnormal (SSS, 4–8), or moderately or severely abnormal (SSS>8). All patients were followed up for a major adverse cardiac event (MACE). ResultsAt the end of a mean follow-up period of 2.2±0.8 years, there had occurred 42 MACEs [17 all-cause deaths (2%) and 25 nonfatal myocardial infarctions (3%)]. The annual frequency of MACEs in patients with normal SSS was 0.5%, that in patients with mildly abnormal SSS was 2%, and in patients with moderately or severely abnormal SSS was 8%. With AC, more studies were categorized as definitely normal, and the number of patients with moderately to severely abnormal perfusion on CT-AC was reduced (&kgr;=0.32, P⩽0.001). The annual frequency of MACEs was similar between studies without AC and those with CT-AC for patients with normal or mildly abnormal SSS, whereas for the moderately to severely abnormal group the annual frequency increased significantly after CT-AC (4.5 vs. 8.1%, P=0.03). Cumulative survival without MACE was highest among patients who had normal CT-AC studies (SSS<4) and was the least among patients who had moderately to severely abnormal studies (SSS>8; P⩽0.01). ConclusionCT-AC allows improved risk stratification for MACEs because there is a more clear separation between low risk and moderately to severely abnormal findings.

Radiography, bone scintigraphy, SPECT/CT and MRI of fibrous dysplasia of the third lumbar vertebra.

A 32-year-old woman, with destruction of bone in the left pedicle of L3 on radiographs, was referred for Tc-99m methylene diphosphonate bone scintigraphy. Planar imaging showed a focal area of increased radioactivity in the left side of the L3 vertebral body. Single photon emission computed tomography/computed tomography (SPECT/CT) fusion imaging disclosed an osteolytic lesion and intense focal uptake at L3, suggesting giant cell tumor of bone. Magnetic resonance imaging (MRI) revealed heterogeneous signal intensities in the left posterior part of L3, suggesting an aneurysmal bone cyst or giant cell tumor. Subsequent surgery and histopathologic examination confirmed fibrous dysplasia (FD) of bone. The diagnosis was based on multiple imaging modalities and was difficult because of the unusual location of the lesion and the absence of characteristic signs.

Risk factors for N2 metastasis in patients with non-small-cell lung cancer: multivariate analyses of 18F-FDG PET/CT data.

ObjectivesN staging is a key factor when considering the choice of treatment for non-small-lung cancer. It is possible that there is a correlation between N2 metastasis and some risk factors. The objective of the present study was to evaluate associations between several risk factors and N2 metastasis using univariate and multivariate analyses, which may assist clinicians in therapeutic planning. Materials and methodsThe enrolled patients were divided into two groups on the basis of histopathological results after surgery: those with pN2 disease (N2+ group) and those without (N2− group). Sex, age, location, size, maximum standardized uptake value (SUVmax) on fluorine-18 fluorodeoxyglucose PET, histopathological type, and tumor cell grade were compared between N2+ and N2− groups. Correlations between each significant factor and groups were analyzed using univariate analyses. Independent risk factors were finally identified with multivariate analyses. ResultsA total of 258 patients met the inclusion criteria. Univariate analyses showed significant correlation between size, SUVmax, tumor cell grade, and N2 status (P<0.05). Multivariate logistic regression showed that both SUVmax and tumor cell grade were independent risk factors and had predictive value for N2 disease (P<0.05). There were no N2 node metastases when tumor SUVmax was up to 2.5 and the tumor cell grade was low. However, the likelihood of metastasis increased to 0.29 and 0.28 when tumor SUVmax was greater than 7.5 and when the tumor cell grade was high. ConclusionSUVmax and tumor cell grade are independent risk factors for N2 metastasis.

Lingual tonsillar metastasis from rectal carcinoma: a rare occurrence.

A 66-year-old man presenting with sacral pain 18 months after radical transabdominal resection of rectal mucinous adenocarcinoma underwent F-FDG PET/CT cancer surveillance. Detection of multiple nodules in lingual tonsil and left neck by imaging initially suggested tonsillar squamous carcinoma (as a second primary) with spread to cervical nodes, given the rarity with which rectal carcinoma metastasizes to the head and neck. Ultimately, the tonsillar neoplasm proved to be adenocarcinoma of colorectal origin based on its shared histologic features and compatible immunostaining profile.

Therapeutic status-dependent thymic changes on 18F-FDG PET/CT in an adult patient with lymphoma who underwent 2 phases of chemotherapy.

A 31-year-old woman who underwent 2 phases of chemotherapy for Hodgkin lymphoma subsequently underwent 8 F-FDG PET/CT scans for staging and treatment response evaluation. The images revealed that the Hounsfield unit and SUV of the thymus changed with the therapeutic status; both decreased to the lowest level 0.5 months after chemotherapy and increased to the highest level 8 to 12 months after the end of treatment. Interestingly, we found a positive correlation between the thymic Hounsfield unit and SUV, with a Spearman correlation coefficient of 0.946 (P < 0.001).