Sophie Turpin

Role of scintigraphy in musculoskeletal and spinal infections.

Clinical findings are still the mainstay for suspecting the diagnosis of musculoskeletal infections, especially osteomyelitis. No single complementary imaging technique has 100% specificity and sensitivity for every case of musculoskeletal infection. Depending on the age of the patient, presence of orthopedic hardware, location of infection, underlying bone, and systemic conditions, the choice of imaging modalities must be tailored to the patients condition. Plain radiographs are performed first and may be sufficient. In children, bone scan is highly accurate to diagnose osteomyelitis. Labeled leukocytes with complementary bone or bone marrow studies are recommended for orthopedic hardware or diabetic foot. Finally, gallium scanning is useful for the diagnosis of vertebral osteomyelitis. Current radiopharmaceuticals used for diagnosing infection also label inflammation. Newer products, as Infecton, should in the future allow better differentiation between infection and sterile inflammation.

Comparison between dipyridamole and adenosine as pharmacologic coronary vasodilators in detection of coronary artery disease with thallium 201 imaging

BackgroundBoth dipyridamole and adenosine are widely used as pharmacologic stressors with 201Tl imaging for detection of coronary artery disease. The purpose of this study was to compare dipyridamole and adenosine 201Tl imaging directly in patients with angiographically proved coronary artery disease.Methods and ResultsFifty-four patients were submitted to two planar 201Tl studies: one with dipyridamole and the other with adenosine. The interval between the two studies varied from 2 to 7 days and the order was assigned randomly. Three standard planar views were obtained 10 minutes and 4 hours after the injection of 3.0 mCi 201Tl. Administration of dipyridamole was as follows: 0.142 mg/kg/min during 4 minutes, followed by a slight exercise and 201Tl injection. The infusion of adenosine was as follows: 0.140 mg/kg/min during 6 minutes with injection of 201Tl after the third minute of infusion. Patients were asked to give their preference considering the number type, severity, and duration of side effects on a scale from 0 (worst) to 5 (best). Reading was done by two experienced observers. The heart was divided into three segments per view. The change in systolic blood pressure was-12±11 mm Hg for adenosine and-5±10 mm Hg for dipyridamole (p<0.001), and the change in heart rate was 18±10 beats/min for adenosine and 8±7 beats/min for dipyridamole (p<0.001). With regions of interest, ischemic/normal wall ratios were determined: 0.78 ± 0.06 for adenosine and 0.83±0.08 for dipyridamole (p<0.001). Adenosine detected 295 normal, 170 ischemic, and 21 scar segments, whereas dipyridamole detected 326, 135, and 25 segments, respectively. Patients preferred adenosine (4.3±1.0 for adenosine vs 3.8±1.5 for dipyridamole; p<0.04) mainly because of the short duration of side effects.ConclusionThis study shows that the use of adenosine with 201Tl imaging may have some advantages over dipyridamole.

A high prevalence of dual thyroid ectopy in congenital hypothyroidism: evidence for insufficient signaling gradients during embryonic thyroid migration or for the polyclonal nature of the thyroid gland?

BACKGROUND Thyroid ectopy results from the failure of the thyroid precursor cells to migrate from the primordial pharynx to the anterior part of the neck. Most ectopic thyroids are revealed by congenital hypothyroidism and present as a single round mass at the base of the tongue, with no other thyroid tissue. However, some cases have dual ectopy, with part of the tissue having partially migrated. We hypothesized that this occurs more frequently than previously reported. METHODS To determine the prevalence of dual ectopy, we reviewed the pertechnetate scintigraphies of 81 patients with congenital hypothyroidism from thyroid ectopy diagnosed between 2002 and 2011 at our institution. RESULTS We report a series of seven cases (9%) of dual ectopy, representing an incidence ranging from 1:50,000 to 1:70,000. CONCLUSIONS Almost one in 10 cases with congenital hypothyroidism due to thyroid ectopy has dual ectopy. This suggests that two populations of cells diverged at an early stage of development, which may arise from insufficient signaling gradients in surrounding tissues during early organogenesis or may indirectly support the polyclonal nature of the thyroid.

An unusual looking pacemaker infection imaged with 18F-FDG PET/CT

Recently, F-FDG PET/CT has emerged as a valuable tool to evaluate infection as illustrated in this pediatric case [1–3]. A 9-year-old boy was hospitalized for low-grade fever and induration in the epigastric region. Previously, he had multiple cardiac surgeries for congenital heart disease including an epicardial dual chamber pacemaker implantation tunneled to the left upper abdominal quadrant. After an inconclusive ultrasound of the latter region, an F-FDG PET/CT was performed. Increased activity was found on both the non-attenuation-corrected (NAC) and CT attenuation-corrected (CTAC) images around the pacemaker (double arrow), along the tunnelized wires (thick arrow) and the intra-abdominal leads (thin arrows). No supradiaphragmatic extension was noted. The presence of pacemaker infection was confirmed during surgery [4, 5]. The F-FDG PET/CT confirmed the presence of infection on an emergency basis and helped surgical planning.

Cold reflex sympathetic dystrophy in an adult.

The classical presentation of acute reflex sympathetic dystrophy (RSD) or triple-phase bone scintigraphy usually consists of increased periarticular uptake in each phase. The authors present a rare case of acute adult RSD characterized by bone hypofixation of Tc-99m MDP. Reflex sympathetic dystrophy in adults and children is reviewed.

Intermittent "intermittent" hydronephrosis.

A 65-year-old woman was evaluated for recurrent right flank pain. She had one episode each decade for 40 years. The findings of repeated excretory urograms were normal. Tc-99m DTPA renograms with furosemide did not reveal obstruction. The renogram was repeated during an acute right flank pain episode and showed right kidney obstruction. A retrograde ureterogram was performed the next day, after the pain had resolved, and was normal. At surgery, an aberrant vessel crossing the ureteropelvic (UP) junction was found. The patient underwent an Anderson-Hynes dismembered pyeloplasty and has been symptom free since.

Ga-67 scintigraphy in a patient with infected vascular synthetic graft.

Ga-67 citrate scintigraphy has be used extensively to locate infectious foci. Infections of a synthetic vascular graft is a rare but catastrophic complication of aortobifemoral bypasses. They can be identified on Ga-67 or labeled leukocytes scans. Usually, they are seen as focal, sometimes ill-defined, uptake on Ga-67 scintigraphy. The authors report a case of an extensive aortobifemoral graft infection giving a lambda image in the abdomen

Another "rim sign". A patent processus vaginalis demonstrated by peritoneal Tc-99m sc scintigraphy.

The rim sign Is usually associated with a missed testicular torsion. Here, a rim sign was demonstrated during peritoneoscintigraphy, in a case of an indirect Ingulnal hernia. Activity was found not only along the inguinal canal, but also around the testicle due to a large patent processus vaginalis. An intravenous injection of Tc-99m pertechnetate helped evaluate the respective size of the right and left sides of the scrotum.

F-18 FDG brain PET and Tc-99m ECD brain SPECT in a patient with multiple recurrent epileptic seizures.

The combination of interictal brain fluorine-18 fluorodeoxyglucose positron emission tomography (F18-FDG PET) and ictal brain Tc-99m ethylcysteinate dimer (ECD) SPECT is currently used for identification of epileptic foci. Usually, hypometabolism is demonstrated on the F-18 FDG PET and hyperperfusion in the same region on the Tc-99m ECD ictal SPECT. The authors report a rare occurrence of left frontal hypermetabolism in a young girl with multiple recurring epileptic seizures, on F18-FDG PET, which was confirmed on ictal Tc-99m ECD SPECT. The patient’s seizures were characterized by head deviation and movements of the upper extremities. The seizures were occurring non stop every 3 to 5 minutes, even during imaging, lasting about 15 seconds. Magnetic resonance imaging (MRI) showed evidence of dysplastic cortex which was consistent with the focal abnormalities on PET and SPECT.

Timing of Hormone Withdrawal in Children Undergoing 131I Whole-Body Scans for Thyroid Cancer

Background: Little objective pediatric data exist to guide the optimal time needed to achieve thyroid-stimulating hormone (TSH) levels ≥30 μIU/mL prior to performing 131I or 123I whole-body scan (WBS) imaging in children with thyroid cancer in the post-thyroidectomy period or after hormone discontinuation. Methods: Retrospective study of patients aged 5-19 years who underwent WBS. Patient data collection included type and duration of withdrawal (liothyronine [L-T3], levothyroxine [L-T4], or post-thyroidectomy status without hormonal replacement) and TSH measured prior to WBS (level and timing). Results: A total of 175 TSH level measurements were performed in 68 patients. Thirty-five TSH values were obtained 2-7 weeks postoperatively and 101 values were obtained 2-8 weeks post L-T4 withdrawal. One patient in each group had a TSH level <30 μIU/mL. There was no difference in TSH levels between 3 weeks and 4 weeks postoperatively (p = 0.14) or post L-T4 cessation (p = 0.21). Thirty-nine TSH measurements were obtained 1-28 days post L-T3 withdrawal. Three patients had to be rescheduled due to inadequate TSH levels, including one after 14 days L-T3 withdrawal. Conclusion: TSH levels ≥30 μIU/mL were achieved at 3 weeks post thyroidectomy or after L-T4 withdrawal and after at least 2 weeks following L-T3 cessation.