Prediction of response to neoadjuvant chemotherapy in osteosarcoma using dual-phase (18)F-FDG PET/CT.

OBJECTIVES: We evaluated the ability of dual-phase (18)F-FDG PET/CT to predict the histological response after neoadjuvant chemotherapy (NAC) in osteosarcoma. METHODS: Thirty-one patients with osteosarcoma treated with NAC and surgery were prospectively enrolled. After injection of (18)F-FDG, both early (~60 min) and delayed (~150 min) PET were acquired before and after the completion of NAC. SUVmax, early/delayed SUVmax change (RImax), and early/delayed SUVmean change (RImean) of tumour were measured before (SUV1, RImax1, and RImean1) and after NAC (SUV2, RImax2, and RImean2). Then, we calculated the percentage changes between SUV1 and SUV2 (%SUV). RESULTS: Twelve patients (39%) exhibited good histological response after NAC. SUVmax, RImax, and RImean significantly decreased after NAC. Before NAC, only RImean1 predicted good histological response with the optimal criterion of < 10%, sensitivity of 92%, specificity of 57%, and accuracy of 71%. After NAC, %SUV, SUV2, and RImax2 predicted histological response. By using combined criterion of %SUV and RImax2 or SUV2 and RImean1 or SUV2 and RImax2, accuracies were 81%, 77%, and 77%, respectively. CONCLUSIONS: The histological response after NAC could be predicted by using RImean1 before the initiation of NAC in osteosarcoma. The combined use of SUV and RI values may provide a better prediction. KEY POINTS: • Pretreatment dual-phase FDG-PET was useful to predict histological response in osteosarcoma. • A combination of early and delayed PET may increase the predictive value. • Early/delayed SUV change of tumours significantly decreased after neoadjuvant chemotherapy.

18F-FDG PET/CT findings in endometrial cancer patients: the correlation between SUVmax and clinicopathologic features.

OBJECTIVE: To study 18F-FDG PET/CT findings in endometrial cancer patients, to analyze the correlation between the maximum standardized uptake value (SUVmax) and clinicopathologic tumor characteristics. MATERIAL AND METHOD: Retrospective study included 33 endometrial cancer patients who underwent pre-operative 18F-FDG PET/CT and abdominal CT or MRI from June 2005 to October 2009. Pattern of FDG uptake was classified as focal and diffuse uptake. SUVmax was measured at primary tumor in endometrial cavity and correlated with maximum tumor size, menopausal state, histological grade, depth of myometrial invasion and nodal metastasis. The diagnostic performance of 18F-FDG PET/CT was assessed for primary tumor and lymph node metastasis and correlated with those of CT/MRI. RESULTS: Sensitivity of 18F-FDG PET/CT in primary tumor detection was slightly higher, without significant difference, than that of either CT or MRI (93.9% vs. 87.9%, p = 0.625). The overall SUVmax mean ofthe primary tumor was 8.24 +/- 5.38. The focal FDG uptake pattern was more common than the diffuse uptake pattern (71.0% and 29.0%, respectively), but the SUVmax was higher in the diffuse uptake pattern (diffuse pattern 12.10 +/- 7.47 vs. focal pattern 6.66 +/- 3.33, p = 0.008). There was significant association between the SUVmax of the primary tumor and maximum tumor size (p = 0.001), but not between the SUVmax of the primary tumor and menopause state, histological grade, depth of myometrial invasion and nodal metastasis (p = 0.522, 0.622, 0.694 and 0.601, respectively). For lymph node detection, the sensitivity of 18F-FDG PET/CT were also higher without statistically significant difference, than those of CT/MRI (on patient basis; 80.0% vs. 40.0%, p = 0.500; on nodal basis 64.7% vs. 47.1%, p = 0.453, respectively). CONCLUSION: 18F-FDG PET/CThad slightly higher diagnostic sensitivity than CT/MRIin both primary tumor and lymph node detection. The finding focal uptake pattern is more common, but the diffuse uptake pattern shows higher FDG uptake. The SUVmax of primary tumors was associated with the maximum tumor size, but not associated with menopause state, histologic grade, depth of myometrial invasion and nodal metastasis.

Prognostic value of SUVmax and metabolic tumor volume on 18F-FDG PET/CT in early stage non-small cell lung cancer patients without LN metastasis.

This paper aimed to evaluate the prognostic value of maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) of the primary tumor on (18)F-FDG PET/CT scan in early stage non-small cell cancer (NSCLC) patients without lymph node (LN) metastasis. In the experiment, eighty NSCLC patients pathologically staged as T1N0 or T2N0 were included (M:F=50:30; mean age, 64.8 years). All patients had preoperative (18)F-FDG PET/CT scan and curative surgery. FDG uptake in the primary tumor was measured by SUVmax and MTV with various SUV threshold values. SUVmax, MTV of the primary tumor, age, tumor size, histology and differentiation grade were analyzed for association with disease-free survival (DFS). The experimental results showed that the histology types included adenocarcinoma (n=58), squamous cell carcinoma (n=20), and others (n=2); Twenty-two (27.5%) of the 80 patients had a recurrence during follow-up at a median time of 29.1 months; The median SUVmax was 5.26, and the median MTV2.5 was 2.2 cm(3). Univariate analysis showed higher SUVmax (>4), greater MTV (MTV2.5 >4 cm(3)), and non-squamous histology were significantly associated with shorter period DFS (p=0.001, p=0.030 and p<0.001). In multivariate analysis, higher SUVmax (p=0.004) and adenocarcinoma histology (p=0.005) were associated with shorter DFS. Therefore, high SUVmax (>4) of the primary tumor on preoperative (18)F-FDG PET/CT scan is an independent prognostic factor of shorter DFS in early stage of NSCLC.

Value of F-18 FDG PET/CT in detection and prognostication of isolated extra-axillary lymph node recurrences in postoperative breast cancer.

We assessed the role of F-18 FDG PET/CT in evaluating isolated extra-axillary lymph node recurrences in postoperative breast cancer patients and its prognostic value on clinical outcome. We reviewed PET/CT scans of postoperative breast cancer patients performed at our institution between July 2003 and February 2012. We recorded PET/CT findings, clinicopathologic variables and treatment modalities. We analyzed metabolic parameters from PET/CT and clinicopathologic variables with respect to progression free survival (PFS). A total of 3561 PET/CT scans were performed in 1906 postoperative breast cancer patients with a median interval of 43 month from curative surgery. Fifty seven patients (2.99%) demonstrated isolated extra-axillary nodal recurrences (n=85) on PET/CT (internal mammary node recurrences in 28, supraclavicular 24, infraclavicular 4, interpectoral 8, cervical 12, and mediastinal 9).The median SUVmax was 7.8 (range, 1.8~19.0), and the median node size was 15 mm (range, 6~38 mm). All recurrences were nonpalpable. Based on PET/CT findings, 53 out of 57 patients with extra-axillary node recurrences underwent subsequent chemotherapy/radiation therapy. The estimated 3-year PFS rate was 48.6%. Cutoff points of SUVmax 2.7 and size 14 mm were the best discriminative values for predicting clinical outcome. SUVmax and size of extra-axillary nodal recurrences were significantly correlated to PFS on univariate and multivariate analyses (p<0.001 and p=0.019, respectively).

Diagnostic accuracy of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in differentiated thyroid cancer patients with elevated thyroglobulin and negative (131)I whole body scan: evaluation by thyroglobulin level.

BACKGROUND: To evaluate the diagnostic accuracy of (18)F-FDG PET/CT in detection of recurrent differentiated thyroid cancer (DTC) in patients with elevated stimulated thyroglobulin (Tg) or anti-Tg antibody (Ab) levels, and negative (131)I whole body scan according to the Tg level. METHODS: PET/CT images of well DTC patients who had total thyroidectomy and radioiodine ablation were included. Patients showing elevated Tg titer (≥2.0 ng/ml after TSH stimulation) or elevated anti-Tg titer (≥70.0 IU/ml) while diagnostic radioiodine scan was negative were enrolled. PET/CT was classified as positive or negative on the basis of visual interpretation. The maximum standard uptake values (SUVmax) of the suspected lesions on PET/CT were also recorded. The PET/CT findings were compared with histological or clinical follow-up results based on other imaging modalities and serum Tg/anti-Tg Ab titers. The diagnostic performance of PET/CT was compared among 4 subgroups according to the Tg level [2 ng/ml ≤ stimulated Tg (sTg) < 5 ng/ml, 5 ng/ml ≤ sTg < 10 ng/ml, 10 ng/ml ≤ sTg < 20 ng/ml, and ≥20 ng/ml]. RESULTS: A total of 68 PET/CT images from 60 patients were included, and histological confirmations were available in 32 images. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of PET/CT were 69.4, 66.7, 69.1, 95.6, and 17.4%, respectively. There were 3 PET/CT cases with high anti-Tg Ab level, and low (<2 ng/ml) Tg level, and all 3 were positive of recurrence. The mean SUVmax of the suspected lesions on PET/CT was 2.9 ± 4.5 (range 1.3-29.7). The sensitivity of PET/CT according to Tg levels was 28.6% when Tg was between 2 and 5, 57.1% between 5 and 10, 60.0% between 10 and 20, and 85.7% when Tg was equal to or greater than 20 ng/ml sub-groups, respectively. CONCLUSION: Diagnostic accuracy of FDG PET in radioiodine negative thyroid cancer may vary depending on serum Tg levels at imaging. (18)F-FDG PET/CT is useful in detection and localization of recurrent thyroid cancer in patients with negative diagnostic radioiodine scan despite elevated Tg greater than 20 ng/ml or high anti-Tg Ab titers. In contrast, PET/CT provides little additional information when the Tg is less than 5 ng/ml.

The success rate of initial (131)i ablation in differentiated thyroid cancer: comparison between less strict and very strict low iodine diets.

PURPOSE: To decrease the risk of recurrence or metastasis in differentiated thyroid cancer (DTC), selected patients receive radioactive iodine ablation of remnant thyroid tissue or tumor. A low iodine diet can enhance uptake of radioactive iodine. We compared the success rates of radioactive iodine ablation therapy in patients who followed two different low iodine diets (LIDs). MATERIALS AND METHODS: The success rates of postsurgical radioactive iodine ablation in DTC patients receiving empiric doses of 150 mCi were retrospectively reviewed. First-time radioactive iodine ablation therapy was done in 71 patients following less strict LID and 90 patients following very strict LID. Less strict LID restricted seafood, iodized salt, egg yolk, dairy products, processed meat, instant prepared meals, and multi-vitamins. Very strict LID additionally restricted rice, freshwater fish, spinach, and soybean products. Radioactive iodine ablation therapy was considered successful when follow-up (123)I whole body scan was negative and stimulated serum thyroglobulin level was less than 2.0 ng/mL. RESULTS: The success rate of patients following less strict LID was 80.3% and for very strict LID 75.6%. There was no statistically significant difference in the success rates between the two LID groups (p = 0.48). CONCLUSIONS: Very strict LID may not contribute to improving the success rate of initial radioactive iodine ablation therapy at the cost of great inconvenience to the patient.

Value of Surveillance (18)F-FDG PET/CT in Colorectal Cancer: Comparison with Conventional Imaging Studies.

PURPOSE: To assess the value of PET/CT for detecting local or distant recurrence in patients who undergo surgery for colorectal cancer (CRC) and to compare the accuracy of PET/CT to that of conventional imaging studies (CIS). METHODS: Tumor surveillance PET/CT scans done between March 2005 and December 2009 of disease-free patients after surgery with or without adjuvant chemotherapy for CRC were retrospectively studied. CIS (serial enhanced CT from lung base to pelvis and plain chest radiograph) were performed within 1 month of PET/CT. We excluded patients with distant metastasis on initial staging, a known recurrent tumor, and a lack of follow-up imaging. The final diagnosis was based on at least 6 months of follow-up with colonoscopy, biopsy, and serial imaging studies in combination with carcinoembryonic antigen levels. RESULTS: A total of 262 PET/CT scans of 245 patients were included. Local and distant recurrences were detected in 27 cases (10.3%). On case-based analysis, the overall sensitivity, specificity, and accuracy were 100, 97.0, and 97.3% for PET/CT and 85.1, 97.0, and 95.8% for CIS, respectively. On lesion-based analysis, PET/CT detected more lesions compared to CIS in local recurrence and lung metastasis. PET/CT and CIS detected the same number of lesions in abdominal lymph nodes, hepatic metastasis, and peritoneal carcinomatosis. PET/CT detected two more metachronous tumors than did CIS in the lung and thyroid gland. CONCLUSION: PET/CT detected more recurrences in patients who underwent surgery for CRC than did CIS and had the additional advantage of evaluating the entire body during a single scan.

Depiction of Nidi and Fibrovascular Zones of Osteoid Osteomas Using Gamma-Correction Tc-99m HDP Pinhole Bone Scan and Conventional Radiograph, and Correlation with CT, MRI, and PVC Phantom Imaging.

PURPOSE: For the precise imaging diagnosis of osteoid osteoma (OO), the identification of the nidus and fibrovascular zone (FVZ) is essential. However, the latter sign has received little attention because it is difficult to demonstrate. We applied the recently introduced gamma correction (GC) to depict the FVZ on pinhole bone scan (PBS), conventional radiography (CR), and computed tomography (CT). Non-gamma correction MRI was also analyzed for reference. METHODS: Ten patients with histologically proven diagnoses of OO were enrolled in this retrospective study. PBS, CR, and CT were processed by GC to demonstrate the nidi and FVZ as distinct yet integrating components of OO. PBS was performed using a 4-mm pinhole collimator 3 h after iv injection of 925 to 1,110 MBq (25 to 30 mCi) of Tc-99m HDP, and anteroposterior and mediolateral CR and transverse CT were taken according to the standard technique. MRI sequences included T1- and T2-weighted images. For gamma correction, we utilized the Photo Correction Wizard program of ACD Photo Editor v3.1. A team of three qualified nuclear physician-radiologists, two nuclear physicians, and one MRI specialist read bone scans, radiographs, and MRIs of OO according to each specialty, and orthopaedic aspects and histology were reviewed by one qualified orthopedic surgeon and two qualified pathologists, respectively. Each observer first read the images separately with basic information about the aim of the study given and then in concert. Interpretive disagreement was settled by discussion and consensus. RESULTS: On pinhole scan, nidi were presented as areas of intense tracer uptake in all cases, and, importantly after GC, a thin ring-like zone with lower tracer uptake became visible in seven out of ten cases. GCCR also revealed a thin lucent zone that circumscribed the nidi in six out of ten cases and GCCT in two of four cases. MRI, without GC, presented nidi with high signal in the center and a thin ring-like zone with low signal in the periphery in five out of six cases. Ring-like zones were 1-2 mm in thickness and circumscribed the nidus as an integrated part and, hence, were morphologically interpreted as FVZ. Histologically, the presence of a variously mineralized FVZ was confirmed in four cases, but individual locus-by-locus image-histology correlation could not be accompolished because specimens were fragmentary. In the FVZ, tracer uptake was lower than in nidi, presumably reflecting that bone metabolism in the two parts differs as in their histology. Statistically, no significant correlation existed between the duration of symptoms and imaging demonstrability of the FVZ (Spearman's test r = -0.057, p = 0.877), but parallelism existed in the demonstrability of the FVZ among GC PBS, CR, and CT, and non-correction MRI. CONCLUSIONS: GC was useful to enhance the resolution of PBS, CR, and CT in OO so that both the nidi and FVZ were separately imaged. The use of CG PBS and CR in combination is recommended for the specific diagnosis of OO with information about bone metabolism and anatomical characteristics. PBS and CR are economical and widely available.

Histopathologic findings related to the indeterminate or inadequate results of fine-needle aspiration biopsy and correlation with ultrasonographic findings in papillary thyroid carcinomas.

OBJECTIVE: To determine histopathologic findings related to the indeterminate or inadequate result of fine-needle aspiration biopsy (FNAB) in papillary thyroid carcinomas (PTCs) and to correlate histopathological findings with ultrasonographic features of tumors. MATERIALS AND METHODS: We retrospectively reviewed the medical records of FNAB, histopathologic characteristics, and sonographic findings of the solid portion of 95 PTCs in 95 patients. All cases were pathologically confirmed by surgery. Histopathologic characteristics were analyzed for tumor distribution, microcystic changes, fibrosis, and tumor component. We assumed several histopathologic conditions to be the cause of indeterminate or inadequate results of FNAB, including: 1) an uneven tumor distribution, 2) > 30% microcystic changes, 3) > 30% fibrosis, and 4) < 30% tumor component. Ultrasonographic findings of each PTC were evaluated for echotexture (homogeneous or heterogeneous), echogenicity (markedly hypoechoic, hypoechoic, isoechoic, or hyperechoic), and volume of the nodule. We correlated histopathologic characteristics of the PTC with results of the FNAB and ultrasonographic findings. RESULTS: From 95 FNABs, 71 cases (74%) were confirmed with malignancy or suspicious malignancy (PTCs), 21 (22%) had indeterminate results (atypical cells), and three (4%) were negative for malignancy. None of the assumed variables influenced the diagnostic accuracy of FNAB. Tumor distribution and fibrosis were statistically correlated with ultrasonographic findings of the PTCs (p < 0.05). Uneven tumor distribution was related with small tumor volume, and fibrosis over 30% was correlated with homogeneous echotexture, markedly hypoechoic and hypoechoic echogenicity, and small tumor volume (p < 0.05). CONCLUSION: No histopathologic component was found to correlate with improper results of FNAB in PTCs. In contrast, two histopathologic characteristics, uneven distribution and fibrosis, were correlated with ultrasonographic findings.

Incidental thyroid uptake on F-18 FDG PET/CT: correlation with ultrasonography and pathology.

PURPOSE: To evaluate the usefulness of maximum standard uptake value (max SUV) calculated from F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) examination and findings from ultrasonographic (US) examination on incidentally detected thyroid FDG uptake on FDG PET/CT. MATERIALS AND METHODS: We collected and reviewed FDG PET/CT images performed at our institution from March 2005 to March 2008. This study included 190 subjects with increased FDG uptake of thyroid gland who later underwent thyroid US and histological examinations. Of these subjects, the uptake pattern on FDG PET/CT was classified as either diffuse or focal. The FDG uptake pattern, max SUV, and US findings were evaluated and correlated with the histological results. RESULTS: In the focal FDG uptake pattern cases (n = 148), the mean max SUV of malignant cases was higher than that of benign cases (5.93 +/- 5.35 vs. 3.47 +/- 2.89). Of the diffuse FDG uptake cases (n = 42), nodules were detected in 25 subjects (59.5%) by US examination. Thyroid nodules were well characterized on US studies, and combined findings of suspicious US features or high max SUV of focal FDG uptake lesion increased sensitivity, PPV, NPV, and accuracy. CONCLUSIONS: Focal uptake pattern and high max SUV may be helpful in differentiating benign and malignant nodules on FDG PET/CT. However, US examination provides further information, and for lesions with increased FDG uptake of thyroid, US examination should be recommended.

Voxel-based analysis of Tc-99m ECD brain perfusion SPECT in patients with normal pressure hydrocephalus.

Idiopathic normal pressure hydrocephalus (iNPH) is a reversible dementia characterized by gait disturbance, incontinence and dementia. This study investigates the neuropsychological characteristics and changes of regional cerebral blood flow (rCBF) in patients with iNPH. Ten patients who met the criteria of probable iNPH and 13 normal control subjects were evaluated. The general cognitive function and detailed neuropsychological functions were measured by K-MMSE and comprehensive neuropsychological battery. Tc-99m-ethyl cysteinate dimmer (Tc-99m-ECD) single photon emission computed tomography (SPECT) was performed to measure the rCBF and statistical parametric mapping (SPM) and statistical probabilistic brain anatomic map (SPAM) was applied to the objective analysis of SPECT data. On the neuropsychological examination, all the patients showed abnormality in memory, psychomotor speed and frontal executive function. SPM analysis of SPECT images revealed that rCBF in bilateral thalami, right prefrontal area, bilateral anterior and posterior cingulate gyri, right caudate nucleus, and left parahippocampal gyrus was significantly decreased in patients with iNPH compared to normal controls (uncorrected P<0.005). In SPAM analysis, rCBF reduction was observed in bilateral prefrontal area, anterior, posterior cingulate gyri and caudate nuclei. We have found that rCBF changes occurred predominantly in prefrontal and subcortical areas, the changes were associated with frontal subcortical circuit, and the affected frontal subcortical circuit may contribute to the cognitive decline seen in the iNPH patients. The reduction of rCBF and clinical cognitive impairment are closely connected in patients with iNPH.

Influence of thyroid-stimulating hormone on 18F-fluorodeoxyglucose and 99mTc-methoxyisobutylisonitrile uptake in human poorly differentiated thyroid cancer cells in vitro.

OBJECTIVE: In poorly differentiated thyroid cancer originating from thyroid follicular cells, the ability to concentrate iodine is lost. This makes recurrence undetectable by (131)I whole-body scan. In this situation, other radiopharmaceuticals, such as (18)F-fluorodeoxyglucose ((18)F-FDG) and technetium-99m-methoxyisobutylisonitrile ((99m)Tc-MIBI), are used to evaluate recurrence or metastasis. Some reports suggest that (18)F-FDG uptake is increased by thyroid-stimulating hormone (TSH) stimulation. This study aimed to determine the influence of TSH on (18)F-FDG and (99m)Tc-MIBI uptake in human poorly differentiated thyroid cancer cells in vitro. MATERIALS AND METHODS: The cells were stimulated with 1000 muU/ml of recombinant human thyroid-stimulating hormone (rhTSH) for 1 day, 3 days, and 5 days. Each cell was incubated with 0.5 MBq/ml-1 MBq/ml of (18)F-FDG or 0.5 MBq/ml-1 MBq/ml of (99m)Tc-MIBI for 1 h at 37 degrees C. The uptake of each radiopharmaceutical in the cells was quantified as a percent of whole radioactivity per total viable cell number. The quantification of glucose transporter 1, 2, 3 and 4 mRNA expression was measured using RT-PCR. RESULTS: TSH stimulation increased (18)F-FDG uptake in a time-dependent manner. Following 5 days of rhTSH stimulation, (18)F-FDG uptake was approximately 2.2 times that of the control. The increase in (18)F-FDG uptake following rhTSH stimulation was correlated to the increase in GLUT4 mRNA level. The GLUT1 mRNA level was unchanged. An increased uptake of (99m)Tc-MIBI was observed with a pattern similar to that of (18)F-FDG. The (99m)Tc-MIBI uptake was approximately 1.5 times that of the control 5 days later. CONCLUSIONS: These results suggest that TSH stimulates (18)F-FDG and (99m)Tc-MIBI uptake in poorly differentiated papillary thyroid cancer, and therefore (18)F-FDG-PET or (99m)Tc-MIBI scans under TSH stimulation may be more accurate than under suppression.

A Tc-99m SPECT study of regional cerebral blood flow in patients with transient global amnesia.

OBJECTIVES: This study aimed to determine whether regional cerebral blood flow (rCBF) is abnormal in patients who have Transient Global Amnesia (TGA). METHODS: We obtained noninvasive rCBF measurements using Tc-99m-ethyl cysteinate diamer Single Photon Emission Computed Tomography (SPECT) in 7 patients diagnosed with TGA within 4 days of onset of the amnestic episode while the patients were still symptomatic and in 17 age-matched healthy control subjects. We assessed memory functioning using the Hopkins's Verbal Learning Test (HVLT) and Statistical Parametric Mapping to compare rCBF across diagnostic groups. RESULTS: The patients with TGA were significantly impaired in their performance on the 20-minute delayed recall of the HVLT. They also exhibited significantly decreased rCBF on their SPECT scans in the inferior and middle frontal gyrus bilaterally, with more prominent left-sided reductions in the superior temporal, precentral, and postcentral gyri, as well as increased rCBF primarily in the right hemisphere within the middle temporal, superior temporal, and inferior frontal gyri, cerebellum, and thalamus, compared with the normal control group. CONCLUSION: These findings suggest that lateralized abnormalities in brain functioning are an important component of the pathophysiology of TGA. Lateralized abnormalities may disrupt functions that are relatively specific to the left hemisphere, including receptive language, symbolic representation, and the processing of local features in the environment, while preserving anterograde memory processes. Increased flow to the right hemisphere centered on regions that subserve the functions of expressive language and visuospatial processing, and may represent processes that compensate for flow reductions to the left hemisphere.

Myxoid liposarcoma involving the liver, subcutaneous tissue, and epidural space in a polycystic disease patient.

We present a case of a myxoid liposarcoma involving the liver, subcutaneous tissue, and epidural space in a polycystic disease patient with minimally increased F-18 FDG activity and review the image findings of myxoid liposarcoma.

Assessment of cerebrovascular reserve before and after STA-MCA bypass surgery by SPECT and SPM analysis.

OBJECTIVE: The purpose of this study was to objectively assess the efficacy of superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery using Technetium (Tc)-99m-ethyl cysteinate dimer (ECD) single photon emission computed tomography (SPECT) in patients who underwent STA-MCA bypass surgery. MATERIALS AND METHODS: Brain perfusion SPECT images obtained at baseline and after the administration of acetazolamide were reconstructed using statistical parametric mapping in 23 patients, both before and after STA-MCA bypass surgery. The clinical outcomes of the surgery were also recorded and compared with the hemodynamic changes. A voxel with an uncorrected p-value of less than 0.001 was considered to be statistically significant. RESULTS: SPECT images of the territory supplied by the bypass graft showed an increase in both cerebrovascular flow and reserve at baseline, and the increase was significantly higher following the administration of acetazolamide. All patients showed improvement of clinical symptoms and increased blood flow to the left temporal, parietal, and frontal cortices as well as the thalamus. CONCLUSION: Brain SPECT effectively and objectively demonstrated the improved outcomes of STA-MCA bypass surgery, and thus may be used in postoperative analyses.

F-18 FDG uptake in the nidus of an osteoid osteoma.

Osteoid osteoma is a common skeletal neoplasm with distinctive histologic abnormalities that consist of a central core of vascular osteoid tissue and a peripheral sclerotic zone. We report a case of intense F-18 FDG uptake in the nidus of cortical osteoid osteoma of the distal metaphysis of the right tibia.

Kikuchi Disease Mimicking Malignant Lymphoma on FDG PET/CT.

A 10-year-old girl presented with a 2-month history of intermittent fever and palpable masses in the right side of the neck. Whole body FDG PET/CT imaging was performed, showing multiple FDG-avid nodular masses in cervical and abdominal lymph nodes. The patient then underwent excision biopsy of the enlarged right cervical nymph nodes, which confirmed the diagnosis of Kikuchi disease. After steroid therapy, fever and cervical lymphadenopathy subsided. After 3 months, follow up FDG PET/CT was done, and there was no abnormality. Kikuchi disease could lead to the wrong initial diagnosis of tuberculosis or even malignant lymphoma.

Clinical significance of small pulmonary nodules with little or no 18F-FDG uptake on PET/CT images of patients with nonthoracic malignancies.

UNLABELLED: Small pulmonary nodules with little or no perceptible (18)F-FDG uptake are relatively common findings on combined PET/CT images of patients with nonthoracic malignancies. Interpreting such nodules is often a diagnostic challenge, and this study aimed to evaluate the clinical significance of the nodules. METHODS: Patients with pulmonary nodules < or =1 cm in diameter showing no (18)F-FDG uptake or uptake less than the mediastinal background were included. Nodules with clearly benign or metastatic findings on CT were excluded. One hundred twenty-one patients had either tissue confirmation or clinical follow-up with additional chest images. The subjects were studied by 3 variables: (i) solitary versus multiple nodules, (ii) presence of accompanying benign lung lesion versus absence, and (iii) imperceptible (18)F-FDG uptake versus faint (18)F-FDG uptake. The malignancy rates were calculated for each variable. RESULTS: Of the 121 patients, 24 had malignancy, with a strong possibility of pulmonary metastasis (19.8%). Six of the 44 patients with solitary nodules (13.6%) and 18 of the 77 patients with multiple nodules (23.4%) had malignancies, though there was no statistically significant difference in the incidences of malignancy between the solitary and multiple groups. On the other hand, there was a statistically significant difference (P = 0.040) between the accompanying lung lesion present (8.3%) and absent (24.7%) groups. No statistically significant difference was noted between the (18)F-FDG uptake imperceptible group and faint (18)F-FDG uptake group (20.7% vs. 17.2%). CONCLUSION: For patients with incidental lung nodules of indeterminate nature with no (18)F-FDG uptake or uptake less than that of the mediastinum on PET/CT images, >19% of the cases turned out to be malignant. The nodule was more likely to be malignant when no other benign pulmonary lesions could be identified elsewhere in the lung field. Thus, regardless of the number of nodules and (18)F-FDG uptake, tissue confirmation or close imaging follow-up is necessary when small nodules with imperceptible or faint (18)F-FDG activity are present on the PET/CT images, especially in the absence of accompanying benign lung lesions.