Parathyroid sonography in long-term dialysis

In a prospective study the prevalence of sonographically enlarged parathyroid glands in patients on maintenance hemodialysis was investigated and correlated with clinical and laboratory findings of secondary hyperparathyroidism. We examined 97 unselected patients with a 5 MHz probe. In 34% (33/97) a total of 69 parathyroid glands were detected with a statistically significant correlation between the period of dialysis and the incidence of parathyroid enlargement; 47.8% of the glands were hypoechoic, 34.8% moderately echogenic and 17.3% gave echoes similar to the normal thyroid parenchyma. A correlation was found between the finding of enlarged parathyroid glands and blood levels of calcium and alkaline phosphatase. Parathyroid enlargement was found sonographically before, or in the absence of clinical and laboratory findings of secondary hyperparathyroidism. Sonography is therefore a useful technique for early diagnosis of hyperparathyroidism in patients on maintenance dialysis.     

Parathyroid adenomas and hyperplasia. Dual radionuclide scintigraphy and bone densitometry studies

Dual radionuclide imaging of the neck (Tc-99m pertechnetate and TI-201 thallous chloride) was performed in 22 patients with chemical evidence of hyperparathyroidism (elevated blood calcium and parathormone [PTH] levels). Of these, 19 of 22 had localization of a TI-201 "excess" area on radiothallium-radiotechnetium subtraction images. In 13 patients who have had operative confirmation at this writing, the dual radionuclide imaging was positive in 12 (12/13 = 92.3%). One patient had two parathyroid adenomas, both of which were seen on the images; thus, overall detection was 13 out of 14 or 92.8%. The parathyroid adenomas visualized weighed from 0.06 to 3.0 g; the one not detected weighed 0.25 g. In three patients with parathyroid hyperplasia secondary to renal disease, the subtraction imaging detected eight of 12 glands (66.7%). The forearm bone mineral content and bone density were determined in eight patients with parathyroid adenomas; results were abnormally low in five of these eight. One of the three patients with secondary hyperparathyroidism had an abnormally low radial bone mass. The combination of dual radionuclide imaging and radial bone mass determination may present a useful approach in both localizing abnormal parathyroid tissue and in examining its functional consequences.     

Postoperative parathyroid high-frequency sonography: evaluation of persistent or recurrent hyperparathyroidism

Sixty consecutive postoperative patients with recurrent or persistent hyperparathyroidism were scanned before reoperation using high-frequency (10 MHz) real-time sonography. The sonograms were interpreted prospectively, and the results correlated with subsequent surgical findings to determine the diagnostic accuracy of this technique in the localization of enlarged parathyroid glands. A total of 59 abnormal glands were found in 51 patients at operation: 45 in the neck and 14 in the mediastinum. Sonography identified 37 of the 45 cervical glands for a sensitivity of 82% in the neck. The mediastinum cannot be evaluated by sonography due to the bony thoracic cage, although if the mediastinal glands are included, the overall sensitivity was 63%. In the 14 patients with negative neck explorations but positive mediastinal explorations, sonography was negative in 12 patients, but false-positives were suspected in two patients, yielding a specificity of 86% in the neck. High-frequency sonography is a sensitive, rapid, and noninvasive technique for localizing enlarged cervical parathyroid glands in patients with recurrent or persistent hyperparathyroidism.     

Thallium-technetium-subtraction scintigraphy in secondary hyperparathyroidism

Between 1983 and 1992 thallium-technetium subtraction scintigraphy (TTS) was performed on 74 patients with clinical and biochemical evidence of hyperparathyroidism. Twenty-five of the 53 investigations since 1988 were conducted on patients with renal failure with a suspicion of secondary hyperparathyroidism. In a retrospective study we have evaluated radioisotope scintigraphy for patients with adenoma and for renal failure patients with possible parathyroid hyperplasia. Thirty of 74 patients underwent neck exploration. Scintigraphy detected 17 of 24 parathyroid adenomas (sensitivity 71%). In contrast, in six renal patients who came to operation, scintigraphy localised only 5 of 20 hyperplastic parathyroid glands (sensitivity 25%) and in one renal patient we localised a parathyroid adenoma. A review of the literature shows low detection rates for hyperplasia by TTS to be a common observation. Based on these findings a rational approach is offered for parathyroid localisation in renal patients prior to neck exploration. Correspondence to: T. Hawkins     

Percutaneous ethanol injection of parathyroid tumors under US guidance: treatment for secondary hyperparathyroidism

In 12 patients with secondary hyperparathyroidism, 13 parathyroid tumors detected with the use of sonography and confirmed by fine-needle aspiration biopsy were treated by percutaneous injection of absolute ethanol under ultrasonographic guidance. Indications for this procedure were recurrence of parathyroid tumors after previous subtotal surgery, high surgical risk, or refusal of surgery. Significant volume reductions were recorded for the larger glands; in the smaller ones, structural changes were observed as well. Clinical and biochemical therapeutic effects were obtained in most cases of single hyperplastic glands treated. Percutaneous alcoholic ablation of enlarged parathyroid glands can be used in cases of secondary hyperparathyroidism when surgery is contraindicated or problematic; it can also improve responsiveness to medical therapy, delaying the need for surgery.     

Ultrasonic detection of parathyroid adenomas

High-resolution real time sonography was used to evaluate patients with suspected primary hyperparathyroidism. A total of 12 consecutive patients was scanned pre-operatively. The sensitivity of the procedure was 92% and the specificity 97%. In our hospital sonography is the procedure of choice for localizing enlarged parathyroid glands prior to surgical exploration.     

Diagnosis of recurrent hyperparathyroidism: comparison of MR imaging and other imaging techniques

Several reports have indicated good results with MR imaging of hyperparathyroidism. However, its use in recurrent hyperparathyroidism has not been assessed separately. Thirty patients with recurrent hyperparathyroidism were evaluated by MR with both T1- and T2-weighted images. Twenty-six and 23 of these patients, respectively, also had thallium-201 scintigraphy and high-resolution sonography. For the 28 patients who eventually had surgical exploration and histologic evidence of adenoma (21 cases) or hypoplasia (seven cases), MR accurately located abnormal parathyroid glands in 75% evaluated prospectively and 89% evaluated retrospectively. Scintigraphy located 68% prospectively and 76% retrospectively. Sonography detected 57% prospectively and 67% retrospectively. For patients undergoing three studies, the prospective and retrospective detection rate was significantly better (p less than .05) for MR compared with sonography but was not significantly different for MR and scintigraphy. MR detected three of four mediastinal adenomas evaluated prospectively and retrospectively. One false-positive case was seen with MR, one with scintigraphy, and one with sonography. Thus, MR can be used to locate abnormal parathyroid tissue at a rate equal to or better than scintigraphy or sonography.     

Preoperative parathyroid gland localization with technetium-99m sestamibi in secondary hyperparathyroidism

Technetium-99m sestamibi scintigraphy has become a valuable tool in locating parathyroid glands in patients with primary hyperparathyroidism. The aim of this study was to evaluate its usefulness in secondary hyperparathyroidism. Twenty patients were injected intravenously with 740 MBq of ^99mTc-sestamibi and images were obtained at 15 min and 2 h post injection. All patients underwent parathyroid ultrasonography (US) as well as bilateral surgical neck exploration and 64 parathyroid glands were removed. US revealed at least one enlarged gland in 15/20 patients (75%), while ^99mTc-sestamibi scintigraphy showed focal areas of increased uptake in at least one gland in 17/20 patients (85%). When imaging results for all glands were evaluated according to surgical results, sensitivity was 54% for parathyroid scintigraphy and 41% for US, and specificity was 89% for both imaging techniques. There was a discrepancy between the two imaging modalities in 28 glands (35%). The mean surgical weight of US-positive glands (1492±1436 mg) was significantly higher than that of US-negative glands (775±703 mg) (P<0.05). However, there were no significant differences in weight between sestamibi-positive and sestamibi-negative glands. When only sestamibi-positive glands were considered, a positive correlation between uptake and weight was found (r=0.4, P<0.05). In conclusion, parathyroid US and ^99mTc-sestamibi scintigraphy are complementary imaging techniques in the preoperative localization of abnormal parathyroid glands in patients with secondary hyperparathyroidism. The limited sensitivity of the techniques means that patients will still require bilateral neck exploration; therefore routine preoperative parathyroid scanning in renal patients is not justified. Received 1 June and in revised form 6 August 1997     

Assessment of parathyroid glands in hemodialysis patients by using color Doppler sonography

The aim of this study was to assess the role of color and spectral Doppler ultrasound (CDU) in the evaluation of enlarged parathyroid glands in hemodialysis patients with secondary hyperparathyroidism. Fourteen hemodialysis patients with elevated intact parathyroid hormone (iPTH) levels were evaluated prospectively with CDU. The volume of each observed parathyroid gland and the spectral CDU data (velocities, resistance and pulsatility indices, systolic to diastolic ratio, and flow volume output (FVO)) were noted. The biochemical data (iPTH, calcium, phosphate levels), and CDU results were analyzed with the Spearman correlation test. Two patients were excluded, and 27 enlarged parathyroid glands were observed in 12 patients. The mean total volume of enlarged parathyroid glands per patient was 1.95 cm³ (0.06–5.5 cm³). Arterial supply was demonstrated in 78% (21/27) of enlarged parathyroid glands. Mean total FVO of enlarged glands per patient was 238.5 ml/min (620–0 ml/min) and mean iPTH level was 1,477 pg/ml (643–3,132 pg/ml). The positive correlations of total volume (p = 0.022), iPTH (p = 0.024), and FVO (p = 0.022) were statistically significant. In secondary hyperparathyroidism, total volume of the visualized enlarged parathyroid glands and the total of FVOs per patient are positively correlated with iPTH levels which may help clinical management and follow-up of end-stage renal disease patients.     

Hyperparathyroidism: comparison of MR imaging with radionuclide scanning

Twenty-three patients with hyperparathyroidism were evaluated preoperatively with magnetic resonance (MR) imaging. Twenty patients also underwent thallium-201/technetium-99m scintigraphy. Of 22 patients with primary hyperparathyroidism, 12 had persistent or recurrent disease. One had secondary hyperparathyroidism due to end-stage renal disease. MR imaging allowed accurate localization of abnormal parathyroid glands in 64% evaluated prospectively and 82% evaluated retrospectively. Scintigraphy allowed localization of 60% evaluated prospectively and 70% retrospectively. The two imaging modalities together allowed detection of 68% evaluated prospectively and 91% retrospectively. MR imaging allowed detection of two of five mediastinal adenomas evaluated prospectively and four of five retrospectively. In patients who underwent both imaging studies, MR was more successful in those with previous neck surgery (73% evaluated prospectively and 91% retrospectively) than in those with no prior surgery (57% prospectively and 71% retrospectively). Scintigraphy allowed accurate localization in 64% evaluated prospectively and 64% retrospectively in patients with previous surgery versus 57% prospectively and 86% retrospectively in patients with no prior neck surgery. Four false-positive results were obtained with MR imaging and three with scintigraphy. MR imaging was useful for parathyroid localization in patients with hyperparathyroidism, particularly in patients requiring additional surgery.     

Bildgebende Diagnostik des Hyperparathyreoidismus

Primary hyperparathyroidism is diagnosed by the presence of hypercalcemia, hypercalciuria and elevated serum levels of parathyroid hormone and is treated surgically by removal of the enlarged gland. Both ultrasound and 99m-Tc-MIBI scintigraphy are used to localize enlarged parathyroid glands. With sonography, enlarged parathyroid glands are hypoechoic and are most frequently found dorsally or caudally to the thyroid and medially to the carotid arteries. Ectopic parathyroid glands in the mediastinum can be detected by scintigraphy only. Computed tomography and magnetic resonance imaging are not primarily indicated. The sensitivity of ultrasound is 90% at best. Causes for false negative ultrasound examinations are ectopic glands in the mediastinum, small glands weighing less than 200 mg and large goiters which make assessment of the retrothyroid space difficult. Ultrasound and scintigraphy in combination can achieve a sensitivity of more than 90%. A combination of both is indicated prior to minimally invasive resection and in cases of recurrence or persistence of hyperparathyroidism after resection.     

Echographic localization diagnosis of enlarged parathyroid glands

The authors report on their own experience with the localization of enlarged parathyroid glands by sonography. In a study of 248 patients with hyperparathyroidism, they obtained a sensitivity of 57% and a specificity of 81%, with an overall accuracy of 74%. These results are discussed in detail.     

Radionuclide imaging of parathyroid tumors: historical perspectives and newer techniques

The increasing use of automated blood chemistry screens for serum calcium levels along with improved methods in measuring parathyroid hormone (PTH) levels have made the diagnosis of parathyroid disease a common clinical problem. Parathyroid adenomas account for the majority of primary hyperparathyroidism with diffuse hyperplasia and parathyroid carcinoma occurring less frequently. Early scintigraphic techniques to identify enlarged parathyroids used selenomethionine-75 which was considered to be incorporated into PTH. In general, the sensitivity of scanning the neck using this tracer was related to the size of the enlarged parathyroid, but in large series, the overall sensitivity was less than 50%. Recent work by Ferlin et al, using a Technetium-99m/Thallium-201 subtraction scintigraphic technique has yielded a sensitivity of 92% in identifying pathologically enlarged parathyroid glands. Winzelberg et al modified this technique to allow imaging the mediastinum plus simplifying the subtraction method. In a prospective study with high-resolution sonography, similar sensitivities and specificities were found with sonography and scintigraphy. Tl-201/Tc-99m pertechnetate subtraction scintigraphy appears to be an accurate technique in identifying pathologic parathyroid enlargement. Its ultimate role in the evaluation of patients with suspected hyperparathyroidism still needs to be determined.     

Assessment of thallium-pertechnetate subtraction scintigraphy in hyperparathyroidism

Reliable techniques for detecting and localising abnormal parathyroid tissue have been a persistent problem. We have evaluated thallium-pertechnetate subtraction scintigraphy in a prospective study of 40 patients with clinical and biochemical evidence of hyperparathyroidism prior to parathyroid surgery. Four patients were excluded as they were shown to have goitre, making subtraction scanning non-diagnostic. 89% of parathyroid adenomas (totalling 27 glands in 26 patients) and 41% of hyperplastic glands (17 glands in 6 patients) were accurately localised prior to surgery. These included three retrosternal glands, four patients with renal failure and tertiary hyperparathyroidism and five patients who had previously undergone neck exploration. The apparent discrepancy between detecting hyperplastic and adenomatous glands was associated with the smaller size of the former. For both types of gland, scintigraphy successfully located parathyroids 0.6 g or more in weight. These results suggest that this simple and non-invasive method is a useful technique for locating parathyroid tissue before parathyroid surgery.     

Localization of ectopic parathyroid glands using technetium-99m sestamibi imaging: Comparison with magnetic resonance and computed tomographic imaging

The aim of the study was to compare the accuracy of technetium-99m sestamibi imaging for localization of ectopic parathyroid glands in patients with hyperparathyroidism with that of magnetic resonance (MR) and computed tomographic (CT) imaging. Eleven patients with primary (n=3) or secondary (n=8) hyperparathyroidism were studied with^99mTc sestamibi parathyroid imaging CT and MR imaging. Images of the neck were acquired at 10 min and 2–3 after tracer injection. The three patients with primary hyperparathyroidism and five patients with secondary hyperparathyroidism underwent parathyroidectomy. The ectopic glands were confirmed by histopathological examination of the resected specimens. In respect of 20 parathyroid glands in the eight patients explored surgically, the sensitivity and specificity of sestamibi imaging were 70% (14/20) and 88%, respectively, those of CT, 40% (8/20) and 88%, and those of MR imaging, 60% (12/20) and 88%. Of these patients, three had parathyroid adenomas while five had hyperplasia (17 glands). Sestamibi imaging localized eight ectopic parathyroid glands, which were surgically confirmed (six were located in the thymus and two in the mediastinum). In one patient explored surgically, the ectopic gland was located outside the field of the MR coil. Although the remaining three cases of secondary hyperparathyroidism were not confirmed surgically, these patients demonstrated sestamibi uptake in five parathyroid glands, including three ectopic glands. MR images demonstrated abnormal parathyroid glands in the same regions as sestamibi imaging. Our data indicate that^99mTc-sestamibi imaging should be used initially to localize the ectopic parathyroid glands in patients with hyperparathyroidism for anatomical guidance prior to MR or CT imaging.     

Tc-99m MIBI parathyroid scintigraphy and intact parathyroid hormone levels in hyperparathyroidism

Tc-99m MIBI has been widely used to evaluate hyperparathyroidism based on increased tracer uptake in hyperfunctioning parathyroid tissue. The functional status measurement of parathyroid glands with intact parathyroid hormone (iPTH) levels is also one of the most important diagnostic studies in this disorder. The aim of the current study was to assess the relation between MIBI imaging and iPTH levels. The authors retrospectively reviewed the records of patients with hyperparathyroidism who were referred to their department for Tc-99m MIBI scintigraphy. Sixty-five patients (24 primary and 41 secondary hyperparathyroidism) were included. The iPTH levels ranged from 66.06 to 2,836 pg/ml (normal, 10 to 55 pg/ml). Forty-two patients were MIBI positive and 23 were negative. The iPTH level in the MIBI-positive group was significantly greater than in the negative group in the primary (548 +/- 478 versus 124 +/- 45; = 0.002), secondary (1,155 +/- 692 versus 501 +/- 352; < 0.001), and overall (909 +/- 678 versus 386 +/- 341; < 0.001) groups. For the primary hyperparathyroidism group, 17 of the 24 patients were MIBI positive (71%). When iPTH levels exceeded 200 pg/ml (100%), the diagnostic sensitivity reached 100%. For the secondary hyperparathyroidism group, 25 of 41 patients (61%) were MIBI positive; 24 of 38 patients (63%) had an iPTH level greater than 200 pg/ml, 21 of 27 patients (78%) had an iPTH level greater than 500 pg/ml, and 11 of 12 patients (92%) had an iPTH value greater than 1,000 pg/ml. Tc-99m MIBI parathyroid scintigraphy showed a good correlation with iPTH level for both primary and secondary hyperparathyroidism. Visualization of hyperfunctioning parathyroid glands on Tc-99m MIBI parathyroid scintigraphy was more likely with a higher serum iPTH level in a dose-dependent manner.     

The usefulness of single photon emission computerized tomography with pinhole collimator (P-SPECT) in preoperative localization of hyperfunctioning parathyroid glands in patients with secondary hyperparathyroidism

PURPOSE: In this study the usefulness of parathyroid scintigraphy was evaluated in a group of patients affected by secondary hyperparathyroidism, combining the conventional double-tracer subtraction planar scintigraphy with pinhole-SPECT (P-SPECT) acquisition and comparing the scintigraphic data with those obtained by ultrasonography. MATERIALS AND METHODS: Twenty-four patients with secondary hyperparathyroidism were enrolled, 19 with chronic renal failure on haemodialysis and 5 with renal transplant. All patients underwent parathyroidectomy because of their unresponsiveness to medical therapy and/or severe osteodystrophy. Histology ascertained a single adenoma each in 3 patients and 61 hyperplastic glands in the remaining 21 cases. Before surgery, all patients were submitted to high resolution ultrasonography and afterwards to double-tracer subtraction planar parathyroid scintigraphy ((99m)Tc-pertechnetate/(99m)Tc-tetrofosmin) followed by neck P-SPECT acquisition. RESULTS: P-SPECT was true positive in all 24 patients, while both planar and ultrasonography were false negative in one case. Globally, P-SPECT identified 60/64 hyperfunctioning parathyroid glands, planar 47/64 and ultrasonography 45/64. P-SPECT sensitivity (93.7%) was significantly higher than both planar (73.4%; p<0.001) and ultrasonography (70.3%; p< 0.0005). The difference was also significant (p<0.05) when P-SPECT sensitivity was compared with that obtained combining planar scintigraphy and ultrasonography (84.4%). Moreover, P-SPECT defined the exact number of hyperplastic glands in 85.7% of positive patients, while planar in 60% and ultrasonography in 45%. Only 4 hyperplastic glands were false negative at P-SPECT showing a maximum diameter of 10 mm and a weight ranging from 480 to 500 mg. These glands were also false negative at both planar scintigraphy and ultrasonography which missed further 13 and 15 hyperfunctioning glands, respectively, all detected by P-SPECT. Globally, the latter procedure gave the correct preoperative localization of hyperfunctioning parathyroid glands in 87.5%, planar in 62.5% and ultrasonography in 50%. None of the three procedures had false positive RESULTS: CONCLUSIONS: The data of the present study seem to indicate that P-SPECT is a reliable diagnostic method in preoperative localization of hyperfunctioning parathyroid glands in patients with secondary hyperparathyroidism. This procedure identified a significantly higher number of hyperplastic glands than both double-tracer subtraction planar parathyroid scintigraphy and ultrasonography in our cases, thus proving a more useful guide for the surgeon. Given its low false negative rate, a wider use of P-SPECT is suggested in the preoperative management of patients with secondary hyperparathyroidism undergoing either a first operation of parathyroidectomy or a second operation for recurrence.     

Comparison of imaging methods for diagnosing enlarged parathyroid glands in chronic renal failure

Three noninvasive imaging methods, CT, scintigraphy with 201TlCl and 99mTcO4-, and ultrasonography, were performed on 36 patients with chronic renal failure and secondary hyperparathyroidism. The patients subsequently underwent total parathyroidectomy and parathyroid autograft. The detection rates of the three methods for the 143 excised parathyroid glands were compared according to gland weight and location. Computed tomography detected 53.8% of all glands and 77.6% of 76 glands weighing more than 500 mg. Scintigraphy detected 51.0% of all glands and 77.6% of glands heavier than 500 mg. Ultrasonography detected 42.7% of all glands and 65.8% of glands heavier than 500 mg. The detection rate of upper glands was best with CT (53.5 and 87.9%): that of lower glands was best with scintigraphy (62.0 and 78.6%). Although the combination of the three methods diagnosed 66.4% of all glands and 89.5% of glands heavier than 500 mg, CT and scintigraphy, the best two combinations, visualized 64.3 and 88.2%.     

Primary hyperparathyroidism: can ultrasonography be the only preoperative diagnostic procedure?

Purpose

The purpose of our study was to assess the role of ultrasonography (US) before surgical treatment of primary hyperparathyroidism.

Materials and methods

We retrospectively evaluated 77 patients (60 women, 17 men; mean age 59 years) with primary hyperparathyroidism who underwent parathyroid US prior to surgery. Sixty-five of 77 (84%) patients had undergone ^99mTc- sestamibi (MIBI) scintigraphy. The results were correlated with the surgical and histopathological findings.

Results

Surgery revealed 85 abnormal parathyroid glands in 77 patients (70 adenomas, 15 hyperplasias). The locations of the parathyroid glands were typical cervical (n=77), thyrothymic ligament (n=3), carotid sheath (n=2), and mediastinum (n=3). In two patients, intrathyroid microadenoma was diagnosed by histopathology. Seventyfour enlarged glands in 64 patients were correctly identified at US. Per-patient sensitivity and positive predictive values, respectively, were 84% (64/76) and 99% (64/65) for US, 68% (44/65) and 100% (44/44) for scintigraphy and 91% (59/65) and 98% (59/60) for both techniques combined. We weighed 63 out of 85 glands, obtaining a value of 1,004±1,564 mg; 460 mg (mean±standard deviation; median).

Conclusions

Preoperative detection and localisation of enlarged parathyroid glands can be based on US, an inexpensive and widely available method, limiting the use of scintigraphy to those cases with negative and/or doubtful findings on US.     

Quantitative comparison of technetium-99m tetrofosmin and thallium-201 images of the thyroid and abnormal parathyroid glands.

The aim of the study was to quantitatively compare the scintigraphic images of the thyroid and abnormal parathyroid glands obtained with technetium-99m tetrofosmin and thallium-201 in patients with hyperparathyroidism. Forty-six patients with hyperparathyroidism underwent (201)Tl (74 MBq), (99m)Tc-pertechnetate (74 MBq) and (99m)Tc-tetrofosmin (555-740 MBq) scintigraphy in a single session. Image analysis included the computation of the thyroid/background ratio in the whole study population and the parathyroid/background ratio, parathyroid/thyroid ratio and diagnostic sensitivity in 17 patients who underwent parathyroid surgery. The pertechnetate subtraction technique was used. (201)Tl and (99m)Tc-tetrofosmin showed a similar thyroid/background ratio (1.79+/-0.41 and 1.81+/-0. 47, respectively, P=NS); however, (99m)Tc-tetrofosmin showed a higher parathyroid/background ratio than (201)Tl (2.06+/-0.54 vs 1. 79+/- 0.50, P=0.007). Despite the superior quality of (99m)Tc-tetrofosmin images, both tracers showed identical sensitivity in detecting enlarged parathyroid glands in patients with primary hyperparathyroidism (89%) and in those with secondary hyperparathyroidism (50%).