Radionuclide imaging of the thyroid gland: patterns, pearls, and pitfalls

Optimal thyroid scintigraphy requires an understanding of 1) the embryology, anatomy, and physiology of the thyroid gland; and 2) the properties of the 2 common imaging agents, technetium-99m pertechnetate (Tc-99m) and radioiodine (1-123). The normal gland has a characteristic scintigraphic pattern with these tracers and its uptake can be quantified with 1-123. Thyroid diseases often produce characteristic abnormal patterns. These abnormal patterns could be described as diffuse or focal, homogeneous or heterogeneous, increased or decreased. "Extrathyroidal" localization can be seen with esophageal activity, ectopic tissue, thyroglossal duct cyst, and substernal goiter. Thyroid scintigraphy of neonates, as a follow up to abnormal blood screening, demonstrates typical etiologic patterns. The first step in evaluating a patient with suspected thyroid disease is correlating the normal or abnormal scintigraphic pattern with available biochemical data, clinical history, and physical examination. By integrating the interpretive and technical "pearls" and "pitfalls" outlined in this article, the radiologist can be more confident in establishing a proper diagnosis.     

Gender, muscle, and velocity comparisons of mechanomyographic and electromyographic responses during isokinetic muscle actions

The purpose of this study was to examine the responses of peak torque (PT), mean power output (MP), mechanomyographic (MMG) and electromyographic (EMG) amplitude and mean power frequency (MPF) of the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) in males and females during maximal, concentric isokinetic muscle actions. Subjects performed maximal leg extensions at 60 degrees s(-1), 120 degrees s(-1), 180 degrees s(-1), 240 degrees s(-1), 300 degrees s(-1), 360 degrees s(-1), 420 degrees s(-1), and 480 degrees s(-1). No gender differences were observed, but there were muscle-specific differences for the patterns of MMG MPF, EMG amplitude, and EMG MPF. The MP and MMG amplitude increased to 180-240 degrees s(-1), plateaued, and then decreased to 480 degrees s(-1). MMG MPF for the VL and VM remained unchanged to 300 degrees s(-1), but then increased to 480 degrees s(-1). The EMG amplitude for the RF and EMG MPF for the VL decreased across velocity. Overall, these findings indicated that there were muscle-specific, velocity-related differences in the associations among motor control strategies (EMG amplitude and MPF) and the mechanical aspects of isokinetic muscular activity (MMG amplitude and MPF).     

Haplotype structure and genotype-phenotype correlations of the sulfonylurea receptor and the islet ATP-sensitive potassium channel gene region

The genes for the sulfonylurea receptor (SUR1; encoded by ABCC8) and its associated islet ATP-sensitive potassium channel (Kir6.2; encoded by KCNJ11) are adjacent to one another on human chromosome 11. Multiple studies have reported association of the E23K variant of Kir6.2 with risk of type 2 diabetes. Whether and how E23K itself-or other variant(s) in either of these two closely linked genes-influences type 2 diabetes remains to be fully determined. To better understand genotype-phenotype correlation at this important candidate gene locus, we 1) characterized haplotype structures across the gene region by typing 77 working, high-frequency markers spanning 207 kb and both genes; 2) performed association studies of E23K and nearby markers in >3,400 patients (type 2 diabetes and control) not previously reported in the literature; and 3) analyzed the resulting data for measures of insulin secretion. These data independently replicate the association of E23K with type 2 diabetes with an odds ratio (OR) in the new data of 1.17 (P = 0.003) as compared with an OR of 1.14 provided by meta-analysis of previously published, nonoverlapping data (P = 0.0002). We find that the E23K variant in Kir6.2 demonstrates very strong allelic association with a coding variant (A1369S) in the neighboring SUR1 gene (r(2) > 0.9) across a range of population samples, making it difficult to distinguish which gene and polymorphism in this region are most likely responsible for the reported association. We show that E23K is also associated with decreased insulin secretion in glucose-tolerant control subjects, supporting a mechanism whereby beta-cell dysfunction contributes to the common form of type 2 diabetes. Like peroxisome proliferator-activated receptor gamma, the SUR1/Kir6.2 gene region both contributes to the inherited risk of type 2 diabetes and encodes proteins that are targets for hypoglycemic medications, providing an intriguing link between the underlying mechanism of disease and validated targets for pharmacological treatment.     

Efficacy of multiple intraarterial papaverine infusions for improvement in cerebral circulation time in patients with recurrent cerebral vasospasm

OBJECT: Cerebral vasospasm that is caused by aneurysmal subarachnoid hemorrhage and that is refractory to maximal medical management can be treated with selective intraarterial papaverine infusions. The effects of single papaverine treatments on cerebral circulation time are well known. The purpose of this study was to assess the efficacy of multiple, repeated papaverine infusions on the cerebral circulation time in patients with recurrent vasospasm. METHODS: A retrospective study was conducted in 17 patients who received multiple intraarterial papaverine infusions in 91 carotid artery (CA) territories for the treatment of cerebral vasospasm. Cerebral circulation times were measured from the first angiographic image, in which peak contrast was seen above the supraclinoid internal CA, to the peak filling of cortical veins. Glasgow Outcome Scale (GOS) scores assessed 12 months after discharge were reviewed. Cerebral circulation times in 16 CA territories were measured in a control group of 11 patients. Seventeen patients received a total of 91 papaverine treatments. Prolonged cerebral circulation times improved after 90 (99%) of 91 papaverine treatments. The prepapaverine mean cerebral circulation time was 6.54 seconds (range 3.35-27 seconds) and the immediate postpapaverine mean cerebral circulation time was 4.19 seconds (range 2.1-12.6 seconds), an overall mean decrease of 2.35 seconds (36%, p < 0.001). Recurrent vasospasm reflected by prolonged cerebral circulation times continued to improve with subsequent papaverine infusions. Repeated infusions were just as successful quantitatively as the primary treatment (mean change 2.06 seconds). The mean cerebral circulation time in the control group was 5.21 seconds (range 4-6.8 seconds). In five patients a dramatic reversal of low-attenuation changes was detected on computerized tomography scans. The mean GOS score at 12 months after discharge was 3.4. CONCLUSIONS: The preliminary results indicate that multiple intraarterial papaverine treatments consistently improve cerebral circulation times, even with repeated infusions in cases of recurrent vasospasm.     

Benefits of resection for metachronous lung cancer

OBJECTIVES: The benefits of resection for metachronous lung cancer are not well described. The objective of this study was to evaluate the safety and efficacy of surgical resection for metachronous lung cancers. METHODS: We reviewed the charts of all patients who underwent a second resection for a metachronous lung cancer from July 1, 1988, to December 31, 2002. Type of resection, operative morbidity, mortality, and survival by stage were analyzed. Survival was determined by using the Kaplan-Meier survival method. All patients were pathologically staged by using the 1997 American Joint Committee on Cancer standards. RESULTS: Pulmonary resections were performed in 69 patients who had undergone a previous resection. The mean interval between the first and second resection was 2.4 +/- 2.5 years. Seventy-three percent of patients presented with stage I cancers, 9% with stage II cancers, and 17% with stage III cancers. Lobectomy and wedge resection were performed with equal frequency (42% each) for the metachronous cancers. Operative mortality for the second resection was 5.8%. The mean follow-up after the second resection was 37 months. Overall 5-year actuarial survival for the entire group after the second resection was 33.4%. CONCLUSIONS: Operations for metachronous cancers provided survival that approximated the expected survival for lung cancer. Surgical intervention should be considered as a safe and effective treatment for resectable metachronous lung cancer in patients with adequate physiologic pulmonary reserve.     

Impact of unnecessary exploratory laparotomy on the treatment of patients with metastatic germ cell tumor

PURPOSE: Patients with testicular germ cell tumors (GCTs) may undergo unnecessary diagnostic or surgical procedures when this diagnosis is not considered. In a cohort of patients who underwent exploratory laparotomy for unsuspected metastatic GCT we determined the impact of this surgery on morbidity, therapeutic delay and cancer therapy. MATERIALS AND METHODS: Between 1980 and 2001, 40 patients who underwent exploratory laparotomy for unsuspected metastatic GCT were later referred to our department for management. Patient records were reviewed retrospectively. RESULTS: Mean patient age at exploratory laparotomy was 34 years. All patients had a midline retroperitoneal mass and 14 had disease at other sites. At the time of evaluation at our institution abnormalities on physical examination and testicular sonogram were identified in 8 (20%) and 22 (55%) patients, respectively. Elevated serum alpha-fetoprotein and/or beta-human chorionic gonadotropin were identified in 26 patients (65%). Eight patients (22%) experienced complications from exploratory surgery. The median interval from laparotomy to chemotherapy was 29 days and in 48% of patients the delay in therapy was 30 days or greater. Of patients with a delay of 30 days or greater 60% required intensive chemotherapy (multiple regimens, or high dose or salvage chemotherapy) compared to 26% with a delay of less than 30 days (p = 0.01). CONCLUSIONS: Exploratory laparotomy contributes to therapeutic delay in a substantial number of patients and it complicates cancer therapy. At presentation evidence to suggest GCT was present in all patients, which highlights the importance of physician awareness in making a prompt diagnosis.     

Tumor length and location of cancer on biopsy predict for side specific extraprostatic cancer extension

PURPOSE: We studied preoperative variables in a contemporary series of men who underwent nonnerve sparing radical prostatectomy in an effort to establish criteria that would predict side specific extraprostatic extension (EPE) of cancer. MATERIALS AND METHODS: We reviewed the records of 430 patients who underwent radical prostatectomy for localized prostate cancer with no prior therapy between 1996 and 1998, and for whom we had at least sextant biopsy information. We evaluated biopsy data (Gleason score, maximum length of cancer in positive cores, percent of cancer per involved core, proportion of positive biopsy cores, tumor location and number of positive biopsy cores) and correlated these findings with EPE at the neurovascular bundle and posterior lateral (NVB/PL) region. RESULTS: We found that a higher number of positive cores, a higher biopsy Gleason score on a side, a positive core at the basal region, 50% or greater tumor in the core or a maximum tumor length of 7 mm or greater increased the likelihood that EPE was present at the NVB/PL region on the corresponding side of the prostate. On multivariate analysis maximum tumor length 7 mm or greater and positive basal core location were the strongest independent predictors of EPE at the NVB/PL region on a given side (p <0.0001 and 0.002, respectively). CONCLUSIONS: Excluding any patient with 1 positive biopsy core with a maximum tumor length of 7 mm or greater plus a positive basal core of any tumor length and grade can decrease the risk of EPE at the NVB/PL region to approximately 10%.     

Tumor marker levels in post-chemotherapy cystic masses: clinical implications for patients with germ cell tumors

PURPOSE: Increased tumor markers after induction chemotherapy for patients with germ cell tumor usually represent systemic disease and consequently second line chemotherapy is instituted, while retroperitoneal lymph node dissection (RPLND) is reserved for patients with marker normalization. We report the concentration of alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) in the fluid of post-chemotherapy cystic masses to evaluate this as a potential source for serum marker elevation. MATERIALS AND METHODS: From March 2002 to December 2002, 11 consecutive patients with post-chemotherapy cystic masses underwent RPLND. Following resection, aspirated fluid was analyzed for AFP and HCG. Only 5 post-chemotherapy RPLNDs were performed in patients with increased serum tumor markers, including the 3 patients in our study. Patients with increasing tumor markers and/or multifocal disease with noncystic residual masses after induction chemotherapy underwent salvage chemotherapy despite teratomatous elements in the primary tumor. RESULTS: All 11 patients had teratoma in the orchiectomy specimen and retroperitoneum, including one with malignant transformation. Cystic fluid markers were increased in all patients, 9 of 9 with HCG (range 7.0 to 6,880) and 9 of 11 with AFP (27.5 to 521.2). Two patients with an increased serum AFP before surgery (47.9 and 31.6) had cyst levels of 73.5 and 790.4 respectively. Both serum markers normalized postoperatively. One patient with increased pre-RPLND serum HCG (11.6) had a cyst level of 233. HCG continued to increase postoperatively and the patient died of disease. The remaining 10 patients remain disease free. CONCLUSION: Fluid from cystic teratoma contains variably elevated levels of HCG and AFP in all patients and appears to be independent of serum marker level or pathology. It is possible that a "slow leak" of fluid from cystic teratoma may explain elevated serum markers in selected patients with teratoma and thus may potentially avoid second line chemotherapy.