Biomedical subjects
Publications and source records attributed to R B Howman-Giles.
This report describes a useful application of (99m)Tc-pertechnetate abdominal scintigraphy (Meckel's scan) in the assessment of gastric viability after corrosive injury. The Meckel's scan provided information about residual gastric mucosal function and prognosis in a less invasive manner than more usual methods.
The objective of this study was to evaluate the variability of technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy interpretation by four nuclear medicine physicians for the diagnosis of renal parenchymal abnormality in children, and to compare variability among three different DMSA methods in clinical use: planar alone, single-photon emission tomography (SPET) alone, and planar with SPET. One hundred consecutive DMSA studies were independently interpreted 3 times by four participating nuclear medicine specialists from different departments and in random order. All scans were classified by the presence or absence of renal parenchymal abnormality using the modified four-level grading system of Goldraich. Indices of agreement were the percentage of agreement and the kappa statistic. Disagreement was analysed using children, kidneys and kidney zones (three zones per kidney). Using patients as the unit of analysis, agreement for planar and planar with SPET methods was 87%-88% (kappa 0.74) for the normal-abnormal scan classification. The corresponding agreement value for the SPET alone method was 78% (kappa 0.56). Similarly, substantial disagreement (disagreement > or = 2 categories) occurred in 2.5% and 1.3% of comparisons between observers for planar alone and planar with SPET, respectively, but in 5.2% of comparisons for SPET alone. These results did not vary appreciably whether interpretation of patients, kidneys or kidney zones was compared. It is concluded that the four experienced nuclear medicine physicians showed substantial agreement in the interpretation of planar alone and planar with SPET DMSA scintigraphic images. Interpretation of SPET DMSA images, without planar images, was significantly more variable than interpretation using the two other methods, disagreement occurring in more than 20% of comparisons. SPET DMSA scintigraphy, when used without planar images, does not provide a firm basis for clinical decision making in the care of children who may have renal damage. There is no apparent benefit of reduced variability from the extra provision of SPET data to nuclear medicine physicians who already have planar images.
OBJECTIVES: This study was conducted to assess whether myocardial ischemia and/or infarction are involved in the pathogenesis of late right ventricular dysfunction in adult survivors of atrial baffle repair for transposition of the great arteries in infancy. BACKGROUND: The medium-term success of intraatrial baffle repair for transposition of the great arteries is good, with many patients surviving into adult life, but prognosis can be limited by progressive right ventricular dysfunction. We hypothesized that ongoing myocardial ischemia and/or infarction are important factors in the pathogenesis of this complication. Radionuclide techniques offer an opportunity to study both myocardial perfusion and concomitant ventricular wall motion. METHODS: Dipyridamole sestamibi single-photon emission computed tomography followed by rest sestamibi single-photon emission computed tomography was used to assess right ventricular myocardial perfusion, wall motion, wall thickening and ejection fraction in 22 adolescents/young adults who had undergone atrial baffle repair for simple transposition of the great arteries at median 6.7 (range 0.5 to 54) months of age. The patients were aged 10 to 25 (median 15.5) years; 19 in New York Heart Association class I, 2 in class II and 1 in class III. All were in a regular cardiac rhythm during the studies. The right ventricular tomographic images were examined in three parallel and two orthogonal planes, analyzed in 12 segments. RESULTS: Perfusion defects were evident in all patients in at least one segment, in either the rest or stress images. Twelve patients (55%) demonstrated fixed defects only, nine (41%) had fixed and reversible defects and one (4.5%) had reversible defects only. Concomitant wall-thickening abnormalities occurred in 83% of segments with fixed perfusion defects, mirrored by a reduction in wall motion in 91% of segments analyzed. Right ventricular ejection fraction was correlated with age (R = 0.62; p = 0.002), and with wall-thickening abnormalities (R = 0.60; p < 0.005). CONCLUSIONS: Reversible and fixed perfusion defects with concordant regional wall motion abnormalities occur in the right (systemic) ventricle 10 to 20 years after Mustard repair for transposition of the great arteries; this may be important in the pathogenesis of late right ventricular dysfunction in this group.
UNLABELLED: The purpose of this study was to evaluate the performance of dimercaptosuccinic acid (DMSA) scintigraphy in the diagnosis of acute pyelonephritis and to compare the test performance of the standard technique, planar DMSA, with the newly introduced technique, SPECT DMSA. METHODS: All published animal studies in which DMSA scintigraphy was compared with histopathology, the reference standard for acute pyelonephritis, were identified using a comprehensive search strategy with the MEDLINE and EMBASE databases. Test performances of all DMSA methods and SPECT versus planar DMSA were analyzed using summary receiver operating characteristic (sROC) curves. RESULTS: Seven studies were identified, including 2 of SPECT DMSA. Problems in study design or reporting were common, with numerical errors in 4 studies. Overall, at a sensitivity of 86%, specificity was estimated to be 91%. Detection of acute pyelonephritis was at a lower threshold for SPECT than for planar DMSA (sensitivity/specificity values of 97%0/66% compared with 82%/ 97%), and the overall test performance of SPECT was not demonstrably better than that of planar DMSA. When applied to a group of children with a prevalence of renal damage of 40%, this means that 98% of children with abnormal planar DMSA scans will have renal damage, whereas only 65% of those with abnormal SPECT scans will have renal damage. Planar and SPECT DMSA will miss 11% and 3% of children with renal damage, respectively. Out of 100 children in the hypothetical group with 40% experiencing renal damage, SPECT will identify 6 extra true cases of renal damage at the expense of 19 extra false positives, when compared with planar DMSA. CONCLUSION: Published studies of DMSA test performance are few in number and have significant methodologic problems that should be avoided in future studies. DMSA, particularly the planar technique, performs well for the diagnosis of acute pyelonephritis. Using test performance criteria, SPECT DMSA alone has not been shown to be preferable to the established planar method and will result in a small number of true-positives at the expense of a larger number of false-positives.
Although right ventricular (RV) dysfunction is an important complication in subjects with congenitally corrected transposition of the great arteries, its pathogenesis is poorly understood. We assessed the role of RV myocardial perfusion and found perfusion defects at rest in all 20 patients, involving 4.6 +/- 2.3 of a total of 12 segments; the extent of the resting perfusion defects correlated inversely with the RV ejection fraction.
BACKGROUND: Accurate staging of melanoma patients by sentinel node (SN) biopsy can be achieved only if all SNs draining a given melanoma site are identified and removed for detailed histologic examination. Lymphoscintigraphy with a radiolabeled colloid provides an objective and reliable method of locating SNs and demonstrates that confident prediction of their location is not possible on clinical grounds. STUDY DESIGN: Lymphatic drainage pathways demonstrated by preoperative lymphoscintigraphy for 1,759 patients with primary cutaneous melanomas were reviewed, and locations of SNs in these patients were documented. An SN was defined as any node receiving direct lymphatic drainage from a primary melanoma site. RESULTS: In many instances the cutaneous lymphatic drainage pathways were found to be at variance with longheld concepts of lymphatic anatomy. Several new pathways were identified, draining to SNs in unexpected sites. These included triangular intermuscular space SNs (from upper back and, rarely, upper limb primaries), paraaortic and retroperitoneal SNs (from upper and lower back primaries), and costal margin SNs with onward drainage to internal mammary nodes (from periumbilical primaries). Occasional drainage to node fields on the opposite side of the body was noted from head, neck, and trunk primaries, and drainage to interval nodes (by definition, SNs) outside recognized lymph node fields was also observed. CONCLUSIONS: Knowledge of the possibility of these unusual lymphatic drainage patterns and SN sites should help to ensure the accuracy and completeness of SN identification. Preoperative lymphoscintigraphy to definitively locate SNs is recommended for every patient undergoing an SN biopsy procedure.
A 10-week-old, 31-week gestation preterm boy re-presented with heart failure after an initial episode of neonatal aseptic meningitis with positive CSF enterovirus polymerase chain reaction. Investigation demonstrated global myocardial dysfunction with left ventricle posterolateral myocardial infarction. The boy's heart failure was controlled with medical treatment but his myocardial dysfunction persisted 9 months after presentation.
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BACKGROUND: Preoperative cutaneous lymphoscintigraphy (LS) to identify sentinel (first-tier) lymph nodes was performed in 250 consecutive melanoma patients before wide local excision only or wide local excision with sentinel node biopsy. METHODS: The location of the sentinel nodes was marked on the overlying skin in all patients. Whether or not tracer was present in second-tier lymph nodes on the delayed scans was recorded for each patient and related to the lesion site at which the tracer had initially been injected. For 100 consecutive patients the rate of tracer movement through the lymphatic channels was compared to the incidence of second-tier drainage. RESULTS: Second-tier nodes were visualized in all patients with melanomas on the leg and thigh, and in almost all patients with melanomas on the forearm and hand, but were seen less often in patients with more centrally located melanomas. There was a significant correlation between the rate of lymph flow and the incidence of demonstrable second-tier drainage. CONCLUSION: The results suggest that the physiology of the lymphatic system varies depending on the origin of the lymphatic vessel. These findings have important implications for application of the sentinel node biopsy technique in individual patients.
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Preoperative lymphoscintigraphy was performed in 198 consecutive patients with cutaneous melanoma prior to their definitive surgical treatment. After intradermal injection of antimony sulphide colloid labelled with technetium-99m, lymphatic flow rates were measured in each patient and found to vary according to the location of the primary tumour. The fastest flow rates occurred from melanoma sites on the distal limbs, particularly the lower limbs. The slowest flow rates were from the head and neck region and the proximal limbs, especially the upper arms and shoulders. Lack of flow in the early dynamic images occurred most commonly for tumours on the upper arms and shoulders. These results can be used to optimize the timing of blue dye injection prior to surgery and may influence the sentinel node biopsy method to be used in individuals who show no early drainage.
BACKGROUND: Patients with systemic ventricles of right ventricular morphology are at high risk of contractile dysfunction, the cause of which has not been fully elucidated. OBJECTIVE: To assess whether ischaemia or infarction contributes to ventricular impairment in unoperated patients with uncomplicated congenitally corrected transposition of the great arteries (TGA) by studying myocardial perfusion and function. SETTING: Paediatric and adult congenital cardiac clinics of a tertiary referral centre. PATIENTS: Five patients with congenitally corrected TGA but without associated structural cardiac defects (aged 3.5 to 34 years). INTERVENTIONS: Maximal exercise stress testing using standard or modified Bruce protocols. Sestamibi (technetium-99m methoxy isobutyl isonitrile) scanning after isotope injection at maximal exercise and rest. MAIN OUTCOME MEASURES: Maximum exercise capacity; right ventricular myocardial perfusion, regional wall motion, and thickening; right ventricular ejection fraction. RESULTS: The two youngest patients (3.5 and 11 years) had normal exercise capacity for age, while the others had reduced exercise performance. Sestamibi scanning showed reversible myocardial ischaemia in four patients and fixed defects indicating infarction in five. Irreversible defects were mostly associated with impaired wall motion and thickening. The ejection fraction was normal (65%) in the youngest patient but < 55% in the others (mean (SD) 47(11)%). CONCLUSIONS: Patients with unoperated congenitally corrected TGA have a high prevalence of myocardial perfusion defects, with consequent abnormalities of regional wall motion and thickening, and impaired ventricular contractility. These data suggest that ischaemia and infarction are important in the pathogenesis of ventricular failure in this condition.
UNLABELLED: Technetium-99m-dimercaptosuccinic acid (DMSA) scintigraphy is a frequently used diagnostic test in pediatric practice to assess the presence and severity of renal damage. Most commonly it is performed after urinary tract infection. The aim of this study was to investigate the variability in the interpretation of DMSA scans by pediatric nuclear medicine physicians in this clinical setting. METHODS: We selected all 441 scans from children with first-time urinary tract infection who presented between 1993 and 1995 to a pediatric casualty department and who are participants in a prospective cohort study. Two hundred and ninety-four scans were performed at a median time of 7 days after diagnosis, and 147 scans were from children who were free from further infection over a 1-yr follow-up period. Two experienced nuclear medicine physicians independently interpreted the 441 scans according to whether renal damage was present or absent and using the modified 4-level grading system for DMSA abnormality of Goldraich. Apart from being informed that urinary tract infection was the indication for DMSA scintigraphy, no other clinical information was given to the nuclear medicine physicians. The indices of variability used were the percentage of agreement and the kappa statistic. For the grading scale used, both measures were weighted with integers representing the number of categories from perfect agreement. Disagreement was analyzed for children, kidneys and kidney zones. RESULTS: There was agreement in 86% (kappa = 69%) for the normal-abnormal DMSA scan dichotomy, and the weighted agreement was 94% (weighted kappa = 82%) for the grading of abnormality. Disagreement of DMSA scan interpretation of > or =2 grades was present in three cases (0.7%). The same high level of agreement was present for patient, kidney and kidney zone comparisons. Agreement was not influenced by age or timing of scintigraphy after urinary tract infection. CONCLUSION: Two experienced nuclear medicine physicians showed good agreement in the interpretation of DMSA scintigraphy in children after urinary tract infection and using the grading system of Goldraich.
Bone scintigraphy is not performed routinely in the diagnostic work-up of children with leukemia; however, the initial diagnosis of childhood leukemia is often difficult to make and may be delayed. Patients may present with fever and skeletal symptoms and, in such cases, bone scintigraphy may be requested in the early search for a diagnosis. Recognition of the potential scintigraphic abnormalities that result from leukemic infiltration of bone and bone marrow will often facilitate an early diagnosis of leukemia. Bone scans also play a role in detecting osteomyelitis in the immunosuppressed leukemic child with fever and bone pain. This article presents four patients illustrating the salient features of bone scintigraphy in these clinical settings.
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BACKGROUND: The technique of lymphoscintigraphy may allow a more selective approach to the management of clinically negative neck nodes among patients with cutaneous head and neck melanoma. PATIENTS AND METHODS: A group of 97 patients with cutaneous head and neck melanoma had preoperative lymphoscintigraphy using intradermal injections of technetium 99m antimony trisulfide colloid to identify sentinel nodes. Fifty-one patients were eligible for clinical analysis after initial definitive treatment by wide excision only (n = 11), wide excision and elective dissection of the neck (n = 19) or axilla (n = 1), or wide excision and a sentinel node biopsy procedure (n = 20). RESULTS: Sentinel nodes were identified in 95 of 97 lymphoscintigrams, and 85% of patients had multiple sentinel nodes. In 21 patients (22%), sentinel nodes were identified outside the parotid region and the 5 main neck levels, mostly in postauricular nodes (n = 13). Lymphoscintigrams were discordant with clinical predictions in 33 patients (34%). Lymph nodes were positive in 4 elective dissections and 4 sentinel node biopsies. Among 16 patients evaluable after wide excision and a negative sentinel node biopsy, 4 patients subsequently developed metastatic nodes; however, confident identification of all nodes marked as sentinel nodes on lymphoscintigraphy was not achieved at the original biopsy procedure in 3 of these patients. CONCLUSIONS: Lymphoscintigraphy and sentinel node biopsy are more difficult to perform in the head and neck than in other parts of the body. The reliability of sentinel node biopsy based on lymphoscintigraphy may be improved by identifying and marking all nodes that are considered to receive direct lymphatic drainage from the primary melanoma, and by use of a gamma probe intraoperatively.
While performing lymphoscintigraphy to define draining lymph node groups and sentinel nodes in patients with melanoma, the authors have discovered a new lymphatic channel in two patients with tumors in the peri-umbilical area. This channel passes over the right costal margin to an interval node before passing toward the midline, where it passes through the chest wall to reach the internal mammary lymph node chain. Appreciating the possible presence of this channel in patients with periumbilical lesions has important implications for the surgical management and follow-up of these patients.