Ihn-Ho Cho

The clinical efficacy of 18F-FDG-PET/CT in benign and malignant musculoskeletal tumors

ObjectiveMost of the current clinical data on the role of 2-[18F]fluoro-2-deoxy-d-glucose positron emission tomography (18F-FDG-PET) in musculoskeletal tumors come from patients studied with PET and less frequently with hardware fusion PET/computed tomography (CT). And the number of cases in each report is too small to clarify the exact clinical efficacy of PET or PET/CT. This prompted us to analyze our experience with 18F-FDG-PET/CT in a relatively large group of patients with musculoskeletal tumors.Methods18F-FDG-PET/CT was performed on 91 patients from May 2004 to June 2007. The final diagnosis was obtained from surgical biopsy in 83 patients (91%) and clinical follow-up in 8 (9%). We analyzed the characteristics and amount of 18F-FDG uptake in soft tissue and bone tumors, and investigated the ability of 18F-FDG-PET/CT to differentiate malignant from benign tumors. The cutoff maximum standardized uptake value (SUVmax) was calculated using the receiver-operation characteristic curve method. Sensitivity, specificity, and diagnostic accuracy were calculated with cutoff SUVmax and the final diagnosis. Unpaired t test was used for the statistical analysis.ResultsFinal diagnosis revealed 19 benign soft tissue tumors (mean SUVmax 4.7), 27 benign bone tumors (5.1), 25 malignant soft tissue tumors (8.8), and 20 malignant bone tumors (10.8). There was a significant difference in SUVmax between benign and malignant musculoskeletal tumors in total (P < 0.002), soft tissue tumors (P < 0.05), and bone tumors (P < 0.02). Sensitivity, specificity, and diagnostic accuracy were 80%, 65.2%, and 73% in total with cutoff SUVmax 3.8, 80%, 68.4%, and 75% in the soft tissue tumors with cutoff SUVmax 3.8, and 80%, 63%, and 70% in the bone tumors with cutoff SUVmax 3.7.Conclusions18F-FDG-PET/CT reliably differentiated malignant soft tissue and bone tumors from benign ones, although there were many false-positive and falsenegative lesions. Further studies with all kinds of musculoskeletal tumors in large numbers are needed to improve the diagnostic accuracy of 18F-FDG-PET/CT.

Differentiation between malignant and benign pathologic fractures with F-18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography

ObjectiveTo evaluate the efficacy of F-18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG PET/CT) in differentiating malignant from benign pathologic fractures.Materials and methodsF-18 FDG PET/CT was performed on 34 patients with pathologic fractures between May 2004 and June 2007. Fractures were located in tubular bones (26), in the pelvis (six), in the spine (one) and in a rib (one). The FDG uptake pattern at the fracture site was described, whether FDG uptake occurred in the marrow or cortex and soft tissue. Maximum standardized uptake values (SUVmax, the largest value at the region of interest) were measured at the fracture site, including cortical bone, bone marrow and soft tissue. As a reference standard, biopsy was used for 12 patients and clinical follow-up for 22 patients. Sensitivity, specificity and diagnostic accuracy of PET/CT were calculated.ResultsThere were 19 malignant and 15 benign fractures. In the malignant fractures, PET/CT demonstrated high (mean SUVmax 12.0, range 4.3 to 45.7) F-18 FDG uptake in bone marrow in most cases (17 of 19). In benign fractures, there was low FDG uptake (mean SUVmax 2.9, range 0.6 to 5.5) within cortical bone or adjacent soft tissue around the fracture, rarely in the marrow. There were significant differences in the pattern of intramedullary FDG uptake (Pu2009<u20090.001) and in the mean SUVmax (Pu2009<u20090.01) between malignant and benign fractures. The sensitivity, specificity and diagnostic accuracy of F-18 FDG PET/CT were 89.5%, 86.7% and 88.2%, respectively, with a cut-off SUVmax set at 4.7. The time interval between fracture and PET/CT did not significantly influence FDG uptake at the fracture site.ConclusionF-18 FDG PET/CT reliably differentiated between malignant and benign fractures based on the SUVmax and based on medullary uptake, which was characteristic for malignant fractures.

Increased bone mineral turnover without increased glucose utilization in sclerotic and hyperplastic change in fibrous dysplasia.

Fibrous dysplasia is a benign bone disorder. It is diagnosed by distinctive X-ray radiography, CT, and MRI findings. Although bone scintigraphy helps to identify the tumor origin according to accelerated bone turnover, the glucose metabolism in fibrous dysplasia has not yet been investigated. We reported a case of fibrous dysplasia in craniofacial bone which showed signs of the acceleration of bone mineral turnover without elevated glucose utilization by Technetium-99m-HMDP SPECT and Fluorine-18-FDG PET. We concluded that the growth of fibrous dysplasia needed the acceleration of bone mineral turnover without an increase in glucose metabolism.

Acute myocardial infarction as a consequence of stent fracture and plaque rupture after sirolimus-eluting stent implantation

Stent fracture (SF) is emerging as one of the leading causes of late cardiac events after sirolimus-eluting stent (SES) implantation. A 44-year old man was admitted with ST-segment elevated myocardial infarction 22 months after treatment with SES. SF was confirmed by fluoroscopy, intravascular ultrasound study (IVUS) and computerized tomographic study. IVUS demonstrated a soft, ruptured plaque at the site of the SF where the plaque was not covered by the stent strut. This case suggests that rupture of vulnerable plaque because of SF led to thrombosis and acute myocardial infarction.

Diagnostic Accuracy of 64-Slice MDCT Coronary Angiography for the Assessment of Coronary Artery Disease in Korean Patients with Type 2 Diabetes

Background A 64-slice multidetector computed tomography (MDCT) is well known to be a useful noninvasive form of angiography for the general population, but not for certain patients with diabetes. The aim of this study was to investigate the diagnostic accuracy and usefulness of 64-slice MDCT coronary angiography for detecting coronary artery disease in Korean patients with type 2 diabetes mellitus (T2DM). Methods A total of 240 patients were included, 74 of whom had type 2 diabetes (M:F=40:33; 41.8±9.5 years). We compared significant coronary stenosis (>50% luminal narrowing) in MDCT with invasive coronary angiography (ICA) by segment, artery, and patient. We also evaluated the influence of obesity and coronary calcium score on MDCT accuracy. Results Of the 4,064 coronary segments studied, 4,062 segments (T2DM=1,109) were assessed quantitatively by both MDCT and ICA, and 706 segments (T2DM=226) were detected as a significant lesion by ICA in all patients. Sensitivity, specificity, as well as positive and negative predictive values for the presence of significant stenosis in T2DM were: by segment, 89.4%, 96.4%, 85.8%, and 97.4%, respectively; by artery (n=222), 95.1%, 92.9%, 94.4%, and 93.8%, respectively; by patients (n=74), 98.4%, 100.0%, 98.4%, and 90.0%, respectively. Regardless of presence of diabetes, there was no significant difference in diagnostic accuracy. Obesity (≥25 kg/m2) and coronary calcium score did not also affect the diagnostic accuracy of MDCT. Conclusion The 64-slice MDCT coronary angiography was found to have similar diagnostic accuracy with ICA, regardless of diabetes. These results suggest MDCT may be helpful to reduce unnecessary invasive studies for patients with diabetes.

Stent fracture and restenosis after zotarolimus-eluting stent implantation

Stent fracture (SF) has been found in peripheral and coronary vasculatures, and in the latter mostly after implantation of sirolimus- or paclitaxel-eluting stents. We report a patient with a fractured stent associated with restenosis after zotarolimus-eluting stent (ZES) implantation which was confirmed by fluoroscopy, intravascular ultrasound and computerized tomography. To our knowledge, this is the first published report of SF after ZES implantation.

(18)F-FDG PET/CT in inflammatory pseudotumor of the colon causing intussusception.

Inflammatory pseudotumor is a rare benign lesion mimicking malignancy both clinically and radiologically. An accurate diagnosis is still difficult and is based on the histological examination. Since inflammatory pseudotumor is exceptionally rare in the colon, this unexpected lesion can be mistaken for malignancy. We report the first case of inflammatory pseudotumor in the colon that showed 18F-fluorodeoxyglucose (FDG) uptake and acted as the lead point causing colocolic intussusception.

The Impact of Energy Substrates, Hormone Level and Subject-Related Factors on Physiologic Myocardial 18 F-FDG Uptake in Normal Humans

PurposeIn a whole-body 18F-FDG PET/CT, non-specific 18F-FDG uptake of the myocardium is a common finding and can be very variable, ranging from background activity to intense accumulation and inhomogeneity. We investigated the effect of energy substrates and plasma/serum hormones that may have an influence on myocardial 18F-FDG uptake.MethodsF-FDG PET/CT was performed on 100 normal volunteers from November 2007 to August 2008. Blood samples were taken just before 18F-FDG injection from all subjects. Myocardial 18F-FDG uptake was measured as the mean (SUVmean) and maximal (SUVmax) standardized uptake value. The myocardium was delineated on the PET/CT image by a manual volume of interest (VOI). We analyzed the influence of age, sex, presence of diabetes, fasting duration, insulin, glucagon, fasting glucose, lactate, free fatty acid (FFA), epinephrine (EPi), norepinephrine (NEp), free triiodothyronine (T3), free thyroxine (T4), thyroid-stimulating hormone (TSH) and body mass index (BMI).ResultsOverall, 92 subjects (mean age 50.28u2009±u20098.30, male 57) were enrolled. The average of myocardial SUVmean was 2.08 and of myocardial SUVmax was 4.57, respectively and there was a strong linear correlation between SUVmean and SUVmax (ru2009=u20090.98). FFA and fasting duration showed significant negative correlation with myocardial 18F-FDG uptake, respectively (ru2009=u2009−0.40 in FFA; ru2009=u2009−0.41 in fasting duration). No significant relationships were observed between myocardial uptake and age, sex, presence of diabetics, insulin, glucagon, fasting glucose, lactate, EPi, NEp, free T3, free T4, TSH and BMI.ConclusionMyocardial 18F-FDG uptake decreases with longer fasting duration and higher FFA level in normal humans. Modulating myocardial uptake could improve 18F-FDG PET/CT imaging for specific oncologic and cardiovascular indications.

Use of 123I-IMP brain SPET to predict outcome following STA-MCA bypass surgery: cerebral blood flow but not vasoreactivity is a predictive parameter

Abstract. Superficial temporal artery – middle cerebral artery (STA-MCA) bypass surgery might improve the cerebral blood flow (CBF) but fail to reduce the risk of post-surgical events such as ischaemic stroke. In this study, we studied retrospectively whether the risk of post-surgical events corresponded to the change in resting CBF and/or the change in vasoreactivity observed before and after STA-MCA surgery using N-isopropyl-I-123-p-iodoamphetamine (123I-IMP) brain single-photon emission tomography (SPET). 123I-IMP brain SPET images obtained at rest and following acetazolamide challenge both before and after STA-MCA surgery were studied in 30 patients. Resting CBF was estimated semiquantitatively using the resting count ratios of the middle cerebral artery (MCA) area to the cerebellum. Acetazolamide challenge was assumed to result in an average increase in flow of 40% in the cerebellum. The vasoreactive response was then estimated as the ratio of the change in counts (acetazolamide – rest) to the resting cerebellar counts multiplied by 1.4. We classified 14 patients (50.5±19.3 years) into group I, who had a change in their resting CBF from before to after surgery of >10%, and 16 patients (54.0±18.8 years) into group II, who had a change in their resting CBF from before to after surgery of ≤10%. Oxygen-15 positron emission tomography (PET) studies were performed in five patients from group I and five patients from group II. One post-surgical event occurred in group I while there were eight post-surgical events in group II (P<0.05). Resting CBF improved by 20.4%±7.5% in group I and by 0.9%±6.9% in group II patients after surgery (P<0.001). No significant difference in the improvement in vasoreactivity was observed between group I patients (32.6%±17.7%) and group II patients (24.6%±15.6%) following surgery. Patients in the group I PET subset showed normalization of oxygen extraction fraction (OEF) from 0.59±0.09 before surgery to 0.46±0.06 after surgery (P<0.05), while patients in the group II PET subset showed no statistical difference in OEF before surgery (0.58±0.14) and after surgery (0.54± 0.05). We conclude that the outcome of STA-MCA bypass surgery can be predicted by the improvement in resting CBF but not by the improvement in vasoreactivity.

Prevalence of extracardiac findings in the evaluation of ischemic heart disease by multidetector computed tomography

Objective Multidector computed tomography (MDCT) is now commonly used for the evaluation of coronary artery disease. Because MDCT images include many non-cardiac organs and the patient population evaluated is highly susceptible to extracardiac diseases, this study was designed to evaluate the prevalence of extracardiac findings in the MDCT evaluation of ischemic heart disease. Methods From March 2007 to March 2008, a total of six-hundred twenty patients, who underwent 64-slice MDCT evaluations for chest pain, or dyspnea, were enrolled in this study. Cardiac and non-cardiac findings were comprehensively evaluated by a radiologist. Results Enrolled patients included 306 men (49.4%), with a mean age of 66 years. Significant coronary artery stenosis was found in 41.6% of the patients. A total of 158 extracardiac findings were observed in 110 (17.7%) patients. Commonly involved extracardiac organs were lung (36.7%), hepatobiliary system (21.5%), thyroid (19.6%), kidney (10.8%), spine (9.7%) and breast (0.6%). Of those 110 patients, 50 (45.5%) patients underwent further diagnostic investigations. Malignant disease was detected in three (2.7%) patients (lung cancer, pancreatic cancer, and thyroid cancer). Conclusions Extracardiac findings are frequently present and should be a concern in the MDCT evaluation of chest pain syndrome.